[PATCH 00/31] tty: BKL removal

[PATCH 00/31] tty: BKL removal

[Arnd Bergmann]

Hi Greg,

As promised, here is a resend of the patches from
both Alan and myself, making the BKL optional
in the TTY layer. Please apply to your tty-next
tree.

	Arnd

--

Alan Cox (20):
  stallion: prune lock_kernel calls
  istallion: use bit ops for the board flags
  riscom8: kill use of lock_kernel
  isicom: kill off the BKL
  rocket: kill BKL
  synclink: kill the big kernel lock
  cyclades: Kill off BKL usage
  epca: Kill the big kernel lock
  specialix; Kill the BKL
  synclink: reworking locking a bit
  tty: serial - fix various misuses/mishandlings of port->tty
  tty: serial - fix tty back references in termios
  tty: serial - fix tty referencing in set_ldisc
  vc: Locking clean up
  tty: Make vt's have a tty_port
  tty: Move the vt_tty field from the vc_data into the standard
    tty_port
  serial: Change the wait for carrier locking
  serial: add port helpers
  serial: trim locking on the helpers
  serial: Use block_til_ready helper

Arnd Bergmann (11):
  tty: replace BKL with a new tty_lock
  tty: never hold BTM while getting tty_mutex
  tty: fix console_sem lock order
  cdc-acm: remove dead code
  tty: introduce wait_event_interruptible_tty
  tty: reorder ldisc locking
  tty: untangle locking of wait_until_sent
  tty: remove tty_lock_nested
  tty: implement BTM as mutex instead of BKL
  tty: release BTM while sleeping in block_til_ready
  8250: fix set_ldisc operation

 drivers/char/Makefile          |    1 +
 drivers/char/amiserial.c       |   25 +++-
 drivers/char/briq_panel.c      |    6 +-
 drivers/char/cyclades.c        |   22 ++--
 drivers/char/epca.c            |    4 +-
 drivers/char/ip2/ip2main.c     |    4 +
 drivers/char/isicom.c          |   13 +-
 drivers/char/istallion.c       |   68 ++++++-----
 drivers/char/keyboard.c        |   10 +-
 drivers/char/n_hdlc.c          |   16 +-
 drivers/char/n_r3964.c         |   10 +-
 drivers/char/pty.c             |   26 ++--
 drivers/char/riscom8.c         |   14 +-
 drivers/char/rocket.c          |   28 +++--
 drivers/char/selection.c       |   13 ++-
 drivers/char/serial167.c       |    8 +-
 drivers/char/specialix.c       |   13 +-
 drivers/char/stallion.c        |   20 ++-
 drivers/char/sx.c              |   12 +-
 drivers/char/synclink.c        |   21 ++--
 drivers/char/synclink_gt.c     |   92 +++++++-------
 drivers/char/synclinkmp.c      |   43 +++---
 drivers/char/tty_io.c          |  134 +++++++++++---------
 drivers/char/tty_ldisc.c       |   43 +++++--
 drivers/char/tty_mutex.c       |   47 +++++++
 drivers/char/tty_port.c        |    4 +-
 drivers/char/vc_screen.c       |    4 +-
 drivers/char/vt.c              |   19 ++-
 drivers/char/vt_ioctl.c        |   14 +-
 drivers/serial/21285.c         |   10 +-
 drivers/serial/68328serial.c   |    2 +
 drivers/serial/68360serial.c   |    4 +-
 drivers/serial/8250.c          |    9 +-
 drivers/serial/bfin_5xx.c      |    7 +-
 drivers/serial/crisv10.c       |    8 +-
 drivers/serial/imx.c           |   10 +-
 drivers/serial/ioc3_serial.c   |    9 +-
 drivers/serial/ioc4_serial.c   |    9 +-
 drivers/serial/max3100.c       |    7 +-
 drivers/serial/serial_core.c   |  281 +++++++++++++++++++---------------------
 drivers/usb/class/cdc-acm.c    |   12 +--
 drivers/video/console/vgacon.c |    2 -
 include/linux/console_struct.h |    3 +-
 include/linux/istallion.h      |    2 +-
 include/linux/serial_core.h    |    2 +-
 include/linux/tty.h            |   67 ++++++++++
 lib/Kconfig.debug              |   10 ++
 47 files changed, 679 insertions(+), 509 deletions(-)
 create mode 100644 drivers/char/tty_mutex.c

[PATCH 01/31] stallion: prune lock_kernel calls

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

Remove unneeded tty layer lock kernel bits. Relock the needed bits using the
port mutex. The istallion still has brd state races but those are not new
or introduced by the removal of the lock_kernel logic.

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/char/istallion.c |   22 +++++++++++++---------
 drivers/char/stallion.c  |   20 ++++++++++++--------
 2 files changed, 25 insertions(+), 17 deletions(-)

diff --git a/drivers/char/istallion.c b/drivers/char/istallion.c
index 4e395c9..750650c 100644
--- a/drivers/char/istallion.c
+++ b/drivers/char/istallion.c
@@ -14,6 +14,7 @@
  *	the Free Software Foundation; either version 2 of the License, or
  *	(at your option) any later version.
  *
+ *	FIXME: brdp->state needs proper locking.
  */
 
 /*****************************************************************************/
@@ -4011,6 +4012,7 @@ static int stli_getbrdstats(combrd_t __user *bp)
 		return -ENODEV;
 
 	memset(&stli_brdstats, 0, sizeof(combrd_t));
+
 	stli_brdstats.brd = brdp->brdnr;
 	stli_brdstats.type = brdp->brdtype;
 	stli_brdstats.hwid = 0;
@@ -4076,10 +4078,13 @@ static int stli_portcmdstats(struct tty_struct *tty, struct stliport *portp)
 	if (brdp == NULL)
 		return -ENODEV;
 
+	mutex_lock(&portp->port.mutex);
 	if (brdp->state & BST_STARTED) {
 		if ((rc = stli_cmdwait(brdp, portp, A_GETSTATS,
-		    &stli_cdkstats, sizeof(asystats_t), 1)) < 0)
+		    &stli_cdkstats, sizeof(asystats_t), 1)) < 0) {
+			mutex_unlock(&portp->port.mutex);
 			return rc;
+		}
 	} else {
 		memset(&stli_cdkstats, 0, sizeof(asystats_t));
 	}
@@ -4124,6 +4129,7 @@ static int stli_portcmdstats(struct tty_struct *tty, struct stliport *portp)
 	stli_comstats.modem = stli_cdkstats.dcdcnt;
 	stli_comstats.hwid = stli_cdkstats.hwid;
 	stli_comstats.signals = stli_mktiocm(stli_cdkstats.signals);
+	mutex_unlock(&portp->port.mutex);
 
 	return 0;
 }
@@ -4186,15 +4192,20 @@ static int stli_clrportstats(struct stliport *portp, comstats_t __user *cp)
 	if (!brdp)
 		return -ENODEV;
 
+	mutex_lock(&portp->port.mutex);
+
 	if (brdp->state & BST_STARTED) {
-		if ((rc = stli_cmdwait(brdp, portp, A_CLEARSTATS, NULL, 0, 0)) < 0)
+		if ((rc = stli_cmdwait(brdp, portp, A_CLEARSTATS, NULL, 0, 0)) < 0) {
+			mutex_unlock(&portp->port.mutex);
 			return rc;
+		}
 	}
 
 	memset(&stli_comstats, 0, sizeof(comstats_t));
 	stli_comstats.brd = portp->brdnr;
 	stli_comstats.panel = portp->panelnr;
 	stli_comstats.port = portp->portnr;
+	mutex_unlock(&portp->port.mutex);
 
 	if (copy_to_user(cp, &stli_comstats, sizeof(comstats_t)))
 		return -EFAULT;
@@ -4266,8 +4277,6 @@ static long stli_memioctl(struct file *fp, unsigned int cmd, unsigned long arg)
 	done = 0;
 	rc = 0;
 
-	lock_kernel();
-
 	switch (cmd) {
 	case COM_GETPORTSTATS:
 		rc = stli_getportstats(NULL, NULL, argp);
@@ -4290,8 +4299,6 @@ static long stli_memioctl(struct file *fp, unsigned int cmd, unsigned long arg)
 		done++;
 		break;
 	}
-	unlock_kernel();
-
 	if (done)
 		return rc;
 
@@ -4308,8 +4315,6 @@ static long stli_memioctl(struct file *fp, unsigned int cmd, unsigned long arg)
 	if (brdp->state == 0)
 		return -ENODEV;
 
-	lock_kernel();
-
 	switch (cmd) {
 	case STL_BINTR:
 		EBRDINTR(brdp);
@@ -4332,7 +4337,6 @@ static long stli_memioctl(struct file *fp, unsigned int cmd, unsigned long arg)
 		rc = -ENOIOCTLCMD;
 		break;
 	}
-	unlock_kernel();
 	return rc;
 }
 
diff --git a/drivers/char/stallion.c b/drivers/char/stallion.c
index 6049fd7..f2167f8 100644
--- a/drivers/char/stallion.c
+++ b/drivers/char/stallion.c
@@ -807,7 +807,6 @@ static void stl_waituntilsent(struct tty_struct *tty, int timeout)
 		timeout = HZ;
 	tend = jiffies + timeout;
 
-	lock_kernel();
 	while (stl_datastate(portp)) {
 		if (signal_pending(current))
 			break;
@@ -815,7 +814,6 @@ static void stl_waituntilsent(struct tty_struct *tty, int timeout)
 		if (time_after_eq(jiffies, tend))
 			break;
 	}
-	unlock_kernel();
 }
 
 /*****************************************************************************/
@@ -1029,6 +1027,8 @@ static int stl_getserial(struct stlport *portp, struct serial_struct __user *sp)
 	pr_debug("stl_getserial(portp=%p,sp=%p)\n", portp, sp);
 
 	memset(&sio, 0, sizeof(struct serial_struct));
+
+	mutex_lock(&portp->port.mutex);
 	sio.line = portp->portnr;
 	sio.port = portp->ioaddr;
 	sio.flags = portp->port.flags;
@@ -1048,6 +1048,7 @@ static int stl_getserial(struct stlport *portp, struct serial_struct __user *sp)
 	brdp = stl_brds[portp->brdnr];
 	if (brdp != NULL)
 		sio.irq = brdp->irq;
+	mutex_unlock(&portp->port.mutex);
 
 	return copy_to_user(sp, &sio, sizeof(struct serial_struct)) ? -EFAULT : 0;
 }
@@ -1069,12 +1070,15 @@ static int stl_setserial(struct tty_struct *tty, struct serial_struct __user *sp
 
 	if (copy_from_user(&sio, sp, sizeof(struct serial_struct)))
 		return -EFAULT;
+	mutex_lock(&portp->port.mutex);
 	if (!capable(CAP_SYS_ADMIN)) {
 		if ((sio.baud_base != portp->baud_base) ||
 		    (sio.close_delay != portp->close_delay) ||
 		    ((sio.flags & ~ASYNC_USR_MASK) !=
-		    (portp->port.flags & ~ASYNC_USR_MASK)))
+		    (portp->port.flags & ~ASYNC_USR_MASK))) {
+			mutex_unlock(&portp->port.mutex);
 			return -EPERM;
+		}
 	} 
 
 	portp->port.flags = (portp->port.flags & ~ASYNC_USR_MASK) |
@@ -1083,6 +1087,7 @@ static int stl_setserial(struct tty_struct *tty, struct serial_struct __user *sp
 	portp->close_delay = sio.close_delay;
 	portp->closing_wait = sio.closing_wait;
 	portp->custom_divisor = sio.custom_divisor;
+	mutex_unlock(&portp->port.mutex);
 	stl_setport(portp, tty->termios);
 	return 0;
 }
@@ -1147,8 +1152,6 @@ static int stl_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd
 
 	rc = 0;
 
-	lock_kernel();
-
 	switch (cmd) {
 	case TIOCGSERIAL:
 		rc = stl_getserial(portp, argp);
@@ -1173,7 +1176,6 @@ static int stl_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd
 		rc = -ENOIOCTLCMD;
 		break;
 	}
-	unlock_kernel();
 	return rc;
 }
 
@@ -2327,6 +2329,7 @@ static int stl_getportstats(struct tty_struct *tty, struct stlport *portp, comst
 			return -ENODEV;
 	}
 
+	mutex_lock(&portp->port.mutex);
 	portp->stats.state = portp->istate;
 	portp->stats.flags = portp->port.flags;
 	portp->stats.hwid = portp->hwid;
@@ -2358,6 +2361,7 @@ static int stl_getportstats(struct tty_struct *tty, struct stlport *portp, comst
 		(STL_TXBUFSIZE - (tail - head));
 
 	portp->stats.signals = (unsigned long) stl_getsignals(portp);
+	mutex_unlock(&portp->port.mutex);
 
 	return copy_to_user(cp, &portp->stats,
 			    sizeof(comstats_t)) ? -EFAULT : 0;
@@ -2382,10 +2386,12 @@ static int stl_clrportstats(struct stlport *portp, comstats_t __user *cp)
 			return -ENODEV;
 	}
 
+	mutex_lock(&portp->port.mutex);
 	memset(&portp->stats, 0, sizeof(comstats_t));
 	portp->stats.brd = portp->brdnr;
 	portp->stats.panel = portp->panelnr;
 	portp->stats.port = portp->portnr;
+	mutex_unlock(&portp->port.mutex);
 	return copy_to_user(cp, &portp->stats,
 			    sizeof(comstats_t)) ? -EFAULT : 0;
 }
@@ -2451,7 +2457,6 @@ static long stl_memioctl(struct file *fp, unsigned int cmd, unsigned long arg)
 		return -ENODEV;
 	rc = 0;
 
-	lock_kernel();
 	switch (cmd) {
 	case COM_GETPORTSTATS:
 		rc = stl_getportstats(NULL, NULL, argp);
@@ -2472,7 +2477,6 @@ static long stl_memioctl(struct file *fp, unsigned int cmd, unsigned long arg)
 		rc = -ENOIOCTLCMD;
 		break;
 	}
-	unlock_kernel();
 	return rc;
 }
 
-- 
1.7.0.4

[PATCH 02/31] istallion: use bit ops for the board flags

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

This lets us avoid problems with races on the flag changes

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/char/istallion.c  |   36 ++++++++++++++++++------------------
 include/linux/istallion.h |    2 +-
 2 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/drivers/char/istallion.c b/drivers/char/istallion.c
index 750650c..5e9a81d 100644
--- a/drivers/char/istallion.c
+++ b/drivers/char/istallion.c
@@ -14,7 +14,6 @@
  *	the Free Software Foundation; either version 2 of the License, or
  *	(at your option) any later version.
  *
- *	FIXME: brdp->state needs proper locking.
  */
 
 /*****************************************************************************/
@@ -204,9 +203,9 @@ static int		stli_shared;
  *	the board has been detected, and whether it is actually running a slave
  *	or not.
  */
-#define	BST_FOUND	0x1
-#define	BST_STARTED	0x2
-#define	BST_PROBED	0x4
+#define	BST_FOUND	0
+#define	BST_STARTED	1
+#define	BST_PROBED	2
 
 /*
  *	Define the set of port state flags. These are marked for internal
@@ -817,7 +816,7 @@ static int stli_open(struct tty_struct *tty, struct file *filp)
 	brdp = stli_brds[brdnr];
 	if (brdp == NULL)
 		return -ENODEV;
-	if ((brdp->state & BST_STARTED) == 0)
+	if (!test_bit(BST_STARTED, &brdp->state))
 		return -ENODEV;
 	portnr = MINOR2PORT(minordev);
 	if (portnr > brdp->nrports)
@@ -1847,7 +1846,7 @@ static void stli_portinfo(struct seq_file *m, struct stlibrd *brdp, struct stlip
 	rc = stli_portcmdstats(NULL, portp);
 
 	uart = "UNKNOWN";
-	if (brdp->state & BST_STARTED) {
+	if (test_bit(BST_STARTED, &brdp->state)) {
 		switch (stli_comstats.hwid) {
 		case 0:	uart = "2681"; break;
 		case 1:	uart = "SC26198"; break;
@@ -1856,7 +1855,7 @@ static void stli_portinfo(struct seq_file *m, struct stlibrd *brdp, struct stlip
 	}
 	seq_printf(m, "%d: uart:%s ", portnr, uart);
 
-	if ((brdp->state & BST_STARTED) && (rc >= 0)) {
+	if (test_bit(BST_STARTED, &brdp->state) && rc >= 0) {
 		char sep;
 
 		seq_printf(m, "tx:%d rx:%d", (int) stli_comstats.txtotal,
@@ -2356,7 +2355,7 @@ static void stli_poll(unsigned long arg)
 		brdp = stli_brds[brdnr];
 		if (brdp == NULL)
 			continue;
-		if ((brdp->state & BST_STARTED) == 0)
+		if (!test_bit(BST_STARTED, &brdp->state))
 			continue;
 
 		spin_lock(&brd_lock);
@@ -3141,7 +3140,7 @@ static int stli_initecp(struct stlibrd *brdp)
 	}
 
 
-	brdp->state |= BST_FOUND;
+	set_bit(BST_FOUND, &brdp->state);
 	return 0;
 err_unmap:
 	iounmap(brdp->membase);
@@ -3298,7 +3297,7 @@ static int stli_initonb(struct stlibrd *brdp)
 	brdp->panels[0] = brdp->nrports;
 
 
-	brdp->state |= BST_FOUND;
+	set_bit(BST_FOUND, &brdp->state);
 	return 0;
 err_unmap:
 	iounmap(brdp->membase);
@@ -3408,7 +3407,7 @@ stli_donestartup:
 	spin_unlock_irqrestore(&brd_lock, flags);
 
 	if (rc == 0)
-		brdp->state |= BST_STARTED;
+		set_bit(BST_STARTED, &brdp->state);
 
 	if (! stli_timeron) {
 		stli_timeron++;
@@ -3711,7 +3710,7 @@ static int __devinit stli_pciprobe(struct pci_dev *pdev,
 	if (retval)
 		goto err_null;
 
-	brdp->state |= BST_PROBED;
+	set_bit(BST_PROBED, &brdp->state);
 	pci_set_drvdata(pdev, brdp);
 
 	EBRDENABLE(brdp);
@@ -3842,7 +3841,7 @@ static int __init stli_initbrds(void)
 			brdp = stli_brds[i];
 			if (brdp == NULL)
 				continue;
-			if (brdp->state & BST_FOUND) {
+			if (test_bit(BST_FOUND, &brdp->state)) {
 				EBRDENABLE(brdp);
 				brdp->enable = NULL;
 				brdp->disable = NULL;
@@ -4079,7 +4078,7 @@ static int stli_portcmdstats(struct tty_struct *tty, struct stliport *portp)
 		return -ENODEV;
 
 	mutex_lock(&portp->port.mutex);
-	if (brdp->state & BST_STARTED) {
+	if (test_bit(BST_STARTED, &brdp->state)) {
 		if ((rc = stli_cmdwait(brdp, portp, A_GETSTATS,
 		    &stli_cdkstats, sizeof(asystats_t), 1)) < 0) {
 			mutex_unlock(&portp->port.mutex);
@@ -4194,7 +4193,7 @@ static int stli_clrportstats(struct stliport *portp, comstats_t __user *cp)
 
 	mutex_lock(&portp->port.mutex);
 
-	if (brdp->state & BST_STARTED) {
+	if (test_bit(BST_STARTED, &brdp->state)) {
 		if ((rc = stli_cmdwait(brdp, portp, A_CLEARSTATS, NULL, 0, 0)) < 0) {
 			mutex_unlock(&portp->port.mutex);
 			return rc;
@@ -4323,10 +4322,10 @@ static long stli_memioctl(struct file *fp, unsigned int cmd, unsigned long arg)
 		rc = stli_startbrd(brdp);
 		break;
 	case STL_BSTOP:
-		brdp->state &= ~BST_STARTED;
+		clear_bit(BST_STARTED, &brdp->state);
 		break;
 	case STL_BRESET:
-		brdp->state &= ~BST_STARTED;
+		clear_bit(BST_STARTED, &brdp->state);
 		EBRDRESET(brdp);
 		if (stli_shared == 0) {
 			if (brdp->reenable != NULL)
@@ -4382,7 +4381,8 @@ static void istallion_cleanup_isa(void)
 	unsigned int j;
 
 	for (j = 0; (j < stli_nrbrds); j++) {
-		if ((brdp = stli_brds[j]) == NULL || (brdp->state & BST_PROBED))
+		if ((brdp = stli_brds[j]) == NULL ||
+				test_bit(BST_PROBED, &brdp->state))
 			continue;
 
 		stli_cleanup_ports(brdp);
diff --git a/include/linux/istallion.h b/include/linux/istallion.h
index 7faca98..ad700a6 100644
--- a/include/linux/istallion.h
+++ b/include/linux/istallion.h
@@ -86,7 +86,7 @@ struct stlibrd {
 	unsigned long	magic;
 	unsigned int	brdnr;
 	unsigned int	brdtype;
-	unsigned int	state;
+	unsigned long	state;
 	unsigned int	nrpanels;
 	unsigned int	nrports;
 	unsigned int	nrdevs;
-- 
1.7.0.4

[PATCH 03/31] riscom8: kill use of lock_kernel

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

The riscom8 board uses lock_kernel to protect bits of the port setting
ioctl logic. We can use the port mutex for this as the logic is internal
and will also lock set versus open (a locking property that has been lost
somewhere along the way)

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/char/riscom8.c |   14 ++++++++------
 1 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/char/riscom8.c b/drivers/char/riscom8.c
index b02332a..af4de1f 100644
--- a/drivers/char/riscom8.c
+++ b/drivers/char/riscom8.c
@@ -47,7 +47,6 @@
 #include <linux/init.h>
 #include <linux/delay.h>
 #include <linux/tty_flip.h>
-#include <linux/smp_lock.h>
 #include <linux/spinlock.h>
 #include <linux/device.h>
 
@@ -1184,6 +1183,7 @@ static int rc_set_serial_info(struct tty_struct *tty, struct riscom_port *port,
 	if (copy_from_user(&tmp, newinfo, sizeof(tmp)))
 		return -EFAULT;
 
+	mutex_lock(&port->port.mutex);
 	change_speed = ((port->port.flags & ASYNC_SPD_MASK) !=
 			(tmp.flags & ASYNC_SPD_MASK));
 
@@ -1191,8 +1191,10 @@ static int rc_set_serial_info(struct tty_struct *tty, struct riscom_port *port,
 		if ((tmp.close_delay != port->port.close_delay) ||
 		    (tmp.closing_wait != port->port.closing_wait) ||
 		    ((tmp.flags & ~ASYNC_USR_MASK) !=
-		     (port->port.flags & ~ASYNC_USR_MASK)))
+		     (port->port.flags & ~ASYNC_USR_MASK))) {
+			mutex_unlock(&port->port.mutex);
 			return -EPERM;
+		}
 		port->port.flags = ((port->port.flags & ~ASYNC_USR_MASK) |
 			       (tmp.flags & ASYNC_USR_MASK));
 	} else  {
@@ -1208,6 +1210,7 @@ static int rc_set_serial_info(struct tty_struct *tty, struct riscom_port *port,
 		rc_change_speed(tty, bp, port);
 		spin_unlock_irqrestore(&riscom_lock, flags);
 	}
+	mutex_unlock(&port->port.mutex);
 	return 0;
 }
 
@@ -1220,12 +1223,15 @@ static int rc_get_serial_info(struct riscom_port *port,
 	memset(&tmp, 0, sizeof(tmp));
 	tmp.type = PORT_CIRRUS;
 	tmp.line = port - rc_port;
+
+	mutex_lock(&port->port.mutex);
 	tmp.port = bp->base;
 	tmp.irq  = bp->irq;
 	tmp.flags = port->port.flags;
 	tmp.baud_base = (RC_OSCFREQ + CD180_TPC/2) / CD180_TPC;
 	tmp.close_delay = port->port.close_delay * HZ/100;
 	tmp.closing_wait = port->port.closing_wait * HZ/100;
+	mutex_unlock(&port->port.mutex);
 	tmp.xmit_fifo_size = CD180_NFIFO;
 	return copy_to_user(retinfo, &tmp, sizeof(tmp)) ? -EFAULT : 0;
 }
@@ -1242,14 +1248,10 @@ static int rc_ioctl(struct tty_struct *tty, struct file *filp,
 
 	switch (cmd) {
 	case TIOCGSERIAL:
-		lock_kernel();
 		retval = rc_get_serial_info(port, argp);
-		unlock_kernel();
 		break;
 	case TIOCSSERIAL:
-		lock_kernel();
 		retval = rc_set_serial_info(tty, port, argp);
-		unlock_kernel();
 		break;
 	default:
 		retval = -ENOIOCTLCMD;
-- 
1.7.0.4

[PATCH 04/31] isicom: kill off the BKL

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

As with the others we can use the port mutex to get the needed locking
properties and fix the race with open.

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/char/isicom.c |   13 +++++--------
 1 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/char/isicom.c b/drivers/char/isicom.c
index 98310e1..c27e9d2 100644
--- a/drivers/char/isicom.c
+++ b/drivers/char/isicom.c
@@ -124,7 +124,6 @@
 #include <linux/fs.h>
 #include <linux/sched.h>
 #include <linux/serial.h>
-#include <linux/smp_lock.h>
 #include <linux/mm.h>
 #include <linux/interrupt.h>
 #include <linux/timer.h>
@@ -872,7 +871,6 @@ static struct tty_port *isicom_find_port(struct tty_struct *tty)
 static int isicom_open(struct tty_struct *tty, struct file *filp)
 {
 	struct isi_port *port;
-	struct isi_board *card;
 	struct tty_port *tport;
 
 	tport = isicom_find_port(tty);
@@ -1118,8 +1116,7 @@ static int isicom_set_serial_info(struct tty_struct *tty,
 	if (copy_from_user(&newinfo, info, sizeof(newinfo)))
 		return -EFAULT;
 
-	lock_kernel();
-
+	mutex_lock(&port->port.mutex);
 	reconfig_port = ((port->port.flags & ASYNC_SPD_MASK) !=
 		(newinfo.flags & ASYNC_SPD_MASK));
 
@@ -1128,7 +1125,7 @@ static int isicom_set_serial_info(struct tty_struct *tty,
 				(newinfo.closing_wait != port->port.closing_wait) ||
 				((newinfo.flags & ~ASYNC_USR_MASK) !=
 				(port->port.flags & ~ASYNC_USR_MASK))) {
-			unlock_kernel();
+			mutex_unlock(&port->port.mutex);
 			return -EPERM;
 		}
 		port->port.flags = ((port->port.flags & ~ASYNC_USR_MASK) |
@@ -1145,7 +1142,7 @@ static int isicom_set_serial_info(struct tty_struct *tty,
 		isicom_config_port(tty);
 		spin_unlock_irqrestore(&port->card->card_lock, flags);
 	}
-	unlock_kernel();
+	mutex_unlock(&port->port.mutex);
 	return 0;
 }
 
@@ -1154,7 +1151,7 @@ static int isicom_get_serial_info(struct isi_port *port,
 {
 	struct serial_struct out_info;
 
-	lock_kernel();
+	mutex_lock(&port->port.mutex);
 	memset(&out_info, 0, sizeof(out_info));
 /*	out_info.type = ? */
 	out_info.line = port - isi_ports;
@@ -1164,7 +1161,7 @@ static int isicom_get_serial_info(struct isi_port *port,
 /*	out_info.baud_base = ? */
 	out_info.close_delay = port->port.close_delay;
 	out_info.closing_wait = port->port.closing_wait;
-	unlock_kernel();
+	mutex_unlock(&port->port.mutex);
 	if (copy_to_user(info, &out_info, sizeof(out_info)))
 		return -EFAULT;
 	return 0;
-- 
1.7.0.4

[PATCH 05/31] rocket: kill BKL

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

We can use the port mutex for this and also for the hangup path so removing
the problematic use of the hangup mutex in this driver. Fix up the locking
on the various port flags while we are at it.

Ultimately this driver needs to be using tty_port_ helpers which would sort
this out far better.

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/char/rocket.c |   28 +++++++++++++++++++---------
 1 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/drivers/char/rocket.c b/drivers/char/rocket.c
index 0e29a23..79c3bc6 100644
--- a/drivers/char/rocket.c
+++ b/drivers/char/rocket.c
@@ -73,7 +73,6 @@
 #include <linux/tty_driver.h>
 #include <linux/tty_flip.h>
 #include <linux/serial.h>
-#include <linux/smp_lock.h>
 #include <linux/string.h>
 #include <linux/fcntl.h>
 #include <linux/ptrace.h>
@@ -1017,6 +1016,7 @@ static void rp_close(struct tty_struct *tty, struct file *filp)
 	if (tty_port_close_start(port, tty, filp) == 0)
 		return;
 
+	mutex_lock(&port->mutex);
 	cp = &info->channel;
 	/*
 	 * Before we drop DTR, make sure the UART transmitter
@@ -1060,9 +1060,13 @@ static void rp_close(struct tty_struct *tty, struct file *filp)
 			info->xmit_buf = NULL;
 		}
 	}
+	spin_lock_irq(&port->lock);
 	info->port.flags &= ~(ASYNC_INITIALIZED | ASYNC_CLOSING | ASYNC_NORMAL_ACTIVE);
 	tty->closing = 0;
+	spin_unlock_irq(&port->lock);
+	mutex_unlock(&port->mutex);
 	tty_port_tty_set(port, NULL);
+
 	wake_up_interruptible(&port->close_wait);
 	complete_all(&info->close_wait);
 	atomic_dec(&rp_num_ports_open);
@@ -1210,11 +1214,13 @@ static int get_config(struct r_port *info, struct rocket_config __user *retinfo)
 	if (!retinfo)
 		return -EFAULT;
 	memset(&tmp, 0, sizeof (tmp));
+	mutex_lock(&info->port.mutex);
 	tmp.line = info->line;
 	tmp.flags = info->flags;
 	tmp.close_delay = info->port.close_delay;
 	tmp.closing_wait = info->port.closing_wait;
 	tmp.port = rcktpt_io_addr[(info->line >> 5) & 3];
+	mutex_unlock(&info->port.mutex);
 
 	if (copy_to_user(retinfo, &tmp, sizeof (*retinfo)))
 		return -EFAULT;
@@ -1229,10 +1235,13 @@ static int set_config(struct tty_struct *tty, struct r_port *info,
 	if (copy_from_user(&new_serial, new_info, sizeof (new_serial)))
 		return -EFAULT;
 
+	mutex_lock(&info->port.mutex);
 	if (!capable(CAP_SYS_ADMIN))
 	{
-		if ((new_serial.flags & ~ROCKET_USR_MASK) != (info->flags & ~ROCKET_USR_MASK))
+		if ((new_serial.flags & ~ROCKET_USR_MASK) != (info->flags & ~ROCKET_USR_MASK)) {
+			mutex_unlock(&info->port.mutex);
 			return -EPERM;
+		}
 		info->flags = ((info->flags & ~ROCKET_USR_MASK) | (new_serial.flags & ROCKET_USR_MASK));
 		configure_r_port(tty, info, NULL);
 		return 0;
@@ -1250,6 +1259,7 @@ static int set_config(struct tty_struct *tty, struct r_port *info,
 		tty->alt_speed = 230400;
 	if ((info->flags & ROCKET_SPD_MASK) == ROCKET_SPD_WARP)
 		tty->alt_speed = 460800;
+	mutex_unlock(&info->port.mutex);
 
 	configure_r_port(tty, info, NULL);
 	return 0;
@@ -1325,8 +1335,6 @@ static int rp_ioctl(struct tty_struct *tty, struct file *file,
 	if (cmd != RCKP_GET_PORTS && rocket_paranoia_check(info, "rp_ioctl"))
 		return -ENXIO;
 
-	lock_kernel();
-
 	switch (cmd) {
 	case RCKP_GET_STRUCT:
 		if (copy_to_user(argp, info, sizeof (struct r_port)))
@@ -1350,7 +1358,6 @@ static int rp_ioctl(struct tty_struct *tty, struct file *file,
 	default:
 		ret = -ENOIOCTLCMD;
 	}
-	unlock_kernel();
 	return ret;
 }
 
@@ -1471,7 +1478,6 @@ static void rp_wait_until_sent(struct tty_struct *tty, int timeout)
 	       jiffies);
 	printk(KERN_INFO "cps=%d...\n", info->cps);
 #endif
-	lock_kernel();
 	while (1) {
 		txcnt = sGetTxCnt(cp);
 		if (!txcnt) {
@@ -1499,7 +1505,6 @@ static void rp_wait_until_sent(struct tty_struct *tty, int timeout)
 			break;
 	}
 	__set_current_state(TASK_RUNNING);
-	unlock_kernel();
 #ifdef ROCKET_DEBUG_WAIT_UNTIL_SENT
 	printk(KERN_INFO "txcnt = %d (jiff=%lu)...done\n", txcnt, jiffies);
 #endif
@@ -1512,6 +1517,7 @@ static void rp_hangup(struct tty_struct *tty)
 {
 	CHANNEL_t *cp;
 	struct r_port *info = tty->driver_data;
+	unsigned long flags;
 
 	if (rocket_paranoia_check(info, "rp_hangup"))
 		return;
@@ -1520,11 +1526,15 @@ static void rp_hangup(struct tty_struct *tty)
 	printk(KERN_INFO "rp_hangup of ttyR%d...\n", info->line);
 #endif
 	rp_flush_buffer(tty);
-	if (info->port.flags & ASYNC_CLOSING)
+	spin_lock_irqsave(&info->port.lock, flags);
+	if (info->port.flags & ASYNC_CLOSING) {
+		spin_unlock_irqrestore(&info->port.lock, flags);
 		return;
+	}
 	if (info->port.count)
 		atomic_dec(&rp_num_ports_open);
 	clear_bit((info->aiop * 8) + info->chan, (void *) &xmit_flags[info->board]);
+	spin_unlock_irqrestore(&info->port.lock, flags);
 
 	tty_port_hangup(&info->port);
 
@@ -1535,7 +1545,7 @@ static void rp_hangup(struct tty_struct *tty)
 	sDisCTSFlowCtl(cp);
 	sDisTxSoftFlowCtl(cp);
 	sClrTxXOFF(cp);
-	info->port.flags &= ~ASYNC_INITIALIZED;
+	clear_bit(ASYNCB_INITIALIZED, &info->port.flags);
 
 	wake_up_interruptible(&info->port.open_wait);
 }
-- 
1.7.0.4

[PATCH 06/31] synclink: kill the big kernel lock

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

We don't need it while waiting and we can lock the ioctls using the port
mutex. While at it eliminate use of the hangup mutex and switch to the port
mutex.

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/char/synclink.c    |   19 ++++++-----
 drivers/char/synclink_gt.c |   78 +++++++++++++++++++-------------------------
 drivers/char/synclinkmp.c  |   32 +++++++-----------
 3 files changed, 56 insertions(+), 73 deletions(-)

diff --git a/drivers/char/synclink.c b/drivers/char/synclink.c
index 0658fc5..4de1246 100644
--- a/drivers/char/synclink.c
+++ b/drivers/char/synclink.c
@@ -81,7 +81,6 @@
 #include <linux/mm.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
 #include <linux/delay.h>
 #include <linux/netdevice.h>
 #include <linux/vmalloc.h>
@@ -2436,7 +2435,9 @@ static int mgsl_get_stats(struct mgsl_struct * info, struct mgsl_icount __user *
 	if (!user_icount) {
 		memset(&info->icount, 0, sizeof(info->icount));
 	} else {
+		mutex_lock(&info->port.mutex);
 		COPY_TO_USER(err, user_icount, &info->icount, sizeof(struct mgsl_icount));
+		mutex_unlock(&info->port.mutex);
 		if (err)
 			return -EFAULT;
 	}
@@ -2461,7 +2462,9 @@ static int mgsl_get_params(struct mgsl_struct * info, MGSL_PARAMS __user *user_p
 		printk("%s(%d):mgsl_get_params(%s)\n",
 			 __FILE__,__LINE__, info->device_name);
 			
+	mutex_lock(&info->port.mutex);
 	COPY_TO_USER(err,user_params, &info->params, sizeof(MGSL_PARAMS));
+	mutex_unlock(&info->port.mutex);
 	if (err) {
 		if ( debug_level >= DEBUG_LEVEL_INFO )
 			printk( "%s(%d):mgsl_get_params(%s) user buffer copy failed\n",
@@ -2501,11 +2504,13 @@ static int mgsl_set_params(struct mgsl_struct * info, MGSL_PARAMS __user *new_pa
 		return -EFAULT;
 	}
 	
+	mutex_lock(&info->port.mutex);
 	spin_lock_irqsave(&info->irq_spinlock,flags);
 	memcpy(&info->params,&tmp_params,sizeof(MGSL_PARAMS));
 	spin_unlock_irqrestore(&info->irq_spinlock,flags);
 	
  	mgsl_change_params(info);
+	mutex_unlock(&info->port.mutex);
 	
 	return 0;
 	
@@ -2935,7 +2940,6 @@ static int mgsl_ioctl(struct tty_struct *tty, struct file * file,
 		    unsigned int cmd, unsigned long arg)
 {
 	struct mgsl_struct * info = tty->driver_data;
-	int ret;
 	
 	if (debug_level >= DEBUG_LEVEL_INFO)
 		printk("%s(%d):mgsl_ioctl %s cmd=%08X\n", __FILE__,__LINE__,
@@ -2950,10 +2954,7 @@ static int mgsl_ioctl(struct tty_struct *tty, struct file * file,
 		    return -EIO;
 	}
 
-	lock_kernel();
-	ret = mgsl_ioctl_common(info, cmd, arg);
-	unlock_kernel();
-	return ret;
+	return mgsl_ioctl_common(info, cmd, arg);
 }
 
 static int mgsl_ioctl_common(struct mgsl_struct *info, unsigned int cmd, unsigned long arg)
@@ -3109,12 +3110,14 @@ static void mgsl_close(struct tty_struct *tty, struct file * filp)
 
 	if (tty_port_close_start(&info->port, tty, filp) == 0)			 
 		goto cleanup;
-			
+
+	mutex_lock(&info->port.mutex);			
  	if (info->port.flags & ASYNC_INITIALIZED)
  		mgsl_wait_until_sent(tty, info->timeout);
 	mgsl_flush_buffer(tty);
 	tty_ldisc_flush(tty);
 	shutdown(info);
+	mutex_unlock(&info->port.mutex);
 
 	tty_port_close_end(&info->port, tty);	
 	info->port.tty = NULL;
@@ -3162,7 +3165,6 @@ static void mgsl_wait_until_sent(struct tty_struct *tty, int timeout)
 	 * Note: use tight timings here to satisfy the NIST-PCTS.
 	 */ 
 
-	lock_kernel();
 	if ( info->params.data_rate ) {
 	       	char_time = info->timeout/(32 * 5);
 		if (!char_time)
@@ -3192,7 +3194,6 @@ static void mgsl_wait_until_sent(struct tty_struct *tty, int timeout)
 				break;
 		}
 	}
-	unlock_kernel();
       
 exit:
 	if (debug_level >= DEBUG_LEVEL_INFO)
diff --git a/drivers/char/synclink_gt.c b/drivers/char/synclink_gt.c
index 4561ce2..d0f81f5 100644
--- a/drivers/char/synclink_gt.c
+++ b/drivers/char/synclink_gt.c
@@ -40,8 +40,8 @@
 #define DBGBH(fmt) if (debug_level >= DEBUG_LEVEL_BH) printk fmt
 #define DBGISR(fmt) if (debug_level >= DEBUG_LEVEL_ISR) printk fmt
 #define DBGDATA(info, buf, size, label) if (debug_level >= DEBUG_LEVEL_DATA) trace_block((info), (buf), (size), (label))
-//#define DBGTBUF(info) dump_tbufs(info)
-//#define DBGRBUF(info) dump_rbufs(info)
+/*#define DBGTBUF(info) dump_tbufs(info)*/
+/*#define DBGRBUF(info) dump_rbufs(info)*/
 
 
 #include <linux/module.h>
@@ -62,7 +62,6 @@
 #include <linux/mm.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
 #include <linux/netdevice.h>
 #include <linux/vmalloc.h>
 #include <linux/init.h>
@@ -901,8 +900,6 @@ static void wait_until_sent(struct tty_struct *tty, int timeout)
 	 * Note: use tight timings here to satisfy the NIST-PCTS.
 	 */
 
-	lock_kernel();
-
 	if (info->params.data_rate) {
 	       	char_time = info->timeout/(32 * 5);
 		if (!char_time)
@@ -920,8 +917,6 @@ static void wait_until_sent(struct tty_struct *tty, int timeout)
 		if (timeout && time_after(jiffies, orig_jiffies + timeout))
 			break;
 	}
-	unlock_kernel();
-
 exit:
 	DBGINFO(("%s wait_until_sent exit\n", info->device_name));
 }
@@ -1041,8 +1036,37 @@ static int ioctl(struct tty_struct *tty, struct file *file,
 		    return -EIO;
 	}
 
-	lock_kernel();
-
+	switch (cmd) {
+	case MGSL_IOCWAITEVENT:
+		return wait_mgsl_event(info, argp);
+	case TIOCMIWAIT:
+		return modem_input_wait(info,(int)arg);
+	case TIOCGICOUNT:
+		spin_lock_irqsave(&info->lock,flags);
+		cnow = info->icount;
+		spin_unlock_irqrestore(&info->lock,flags);
+		p_cuser = argp;
+		if (put_user(cnow.cts, &p_cuser->cts) ||
+		    put_user(cnow.dsr, &p_cuser->dsr) ||
+		    put_user(cnow.rng, &p_cuser->rng) ||
+		    put_user(cnow.dcd, &p_cuser->dcd) ||
+		    put_user(cnow.rx, &p_cuser->rx) ||
+		    put_user(cnow.tx, &p_cuser->tx) ||
+		    put_user(cnow.frame, &p_cuser->frame) ||
+		    put_user(cnow.overrun, &p_cuser->overrun) ||
+		    put_user(cnow.parity, &p_cuser->parity) ||
+		    put_user(cnow.brk, &p_cuser->brk) ||
+		    put_user(cnow.buf_overrun, &p_cuser->buf_overrun))
+			return -EFAULT;
+		return 0;
+	case MGSL_IOCSGPIO:
+		return set_gpio(info, argp);
+	case MGSL_IOCGGPIO:
+		return get_gpio(info, argp);
+	case MGSL_IOCWAITGPIO:
+		return wait_gpio(info, argp);
+	}
+	mutex_lock(&info->port.mutex);
 	switch (cmd) {
 	case MGSL_IOCGPARAMS:
 		ret = get_params(info, argp);
@@ -1068,50 +1092,16 @@ static int ioctl(struct tty_struct *tty, struct file *file,
 	case MGSL_IOCGSTATS:
 		ret = get_stats(info, argp);
 		break;
-	case MGSL_IOCWAITEVENT:
-		ret = wait_mgsl_event(info, argp);
-		break;
-	case TIOCMIWAIT:
-		ret = modem_input_wait(info,(int)arg);
-		break;
 	case MGSL_IOCGIF:
 		ret = get_interface(info, argp);
 		break;
 	case MGSL_IOCSIF:
 		ret = set_interface(info,(int)arg);
 		break;
-	case MGSL_IOCSGPIO:
-		ret = set_gpio(info, argp);
-		break;
-	case MGSL_IOCGGPIO:
-		ret = get_gpio(info, argp);
-		break;
-	case MGSL_IOCWAITGPIO:
-		ret = wait_gpio(info, argp);
-		break;
-	case TIOCGICOUNT:
-		spin_lock_irqsave(&info->lock,flags);
-		cnow = info->icount;
-		spin_unlock_irqrestore(&info->lock,flags);
-		p_cuser = argp;
-		if (put_user(cnow.cts, &p_cuser->cts) ||
-		    put_user(cnow.dsr, &p_cuser->dsr) ||
-		    put_user(cnow.rng, &p_cuser->rng) ||
-		    put_user(cnow.dcd, &p_cuser->dcd) ||
-		    put_user(cnow.rx, &p_cuser->rx) ||
-		    put_user(cnow.tx, &p_cuser->tx) ||
-		    put_user(cnow.frame, &p_cuser->frame) ||
-		    put_user(cnow.overrun, &p_cuser->overrun) ||
-		    put_user(cnow.parity, &p_cuser->parity) ||
-		    put_user(cnow.brk, &p_cuser->brk) ||
-		    put_user(cnow.buf_overrun, &p_cuser->buf_overrun))
-			ret = -EFAULT;
-		ret = 0;
-		break;
 	default:
 		ret = -ENOIOCTLCMD;
 	}
-	unlock_kernel();
+	mutex_unlock(&info->port.mutex);
 	return ret;
 }
 
diff --git a/drivers/char/synclinkmp.c b/drivers/char/synclinkmp.c
index 2b18adc..8da976b 100644
--- a/drivers/char/synclinkmp.c
+++ b/drivers/char/synclinkmp.c
@@ -52,7 +52,6 @@
 #include <linux/mm.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>
-#include <linux/smp_lock.h>
 #include <linux/netdevice.h>
 #include <linux/vmalloc.h>
 #include <linux/init.h>
@@ -1062,9 +1061,7 @@ static void wait_until_sent(struct tty_struct *tty, int timeout)
 	if (sanity_check(info, tty->name, "wait_until_sent"))
 		return;
 
-	lock_kernel();
-
-	if (!(info->port.flags & ASYNC_INITIALIZED))
+	if (!test_bit(ASYNCB_INITIALIZED, &info->port.flags))
 		goto exit;
 
 	orig_jiffies = jiffies;
@@ -1094,8 +1091,10 @@ static void wait_until_sent(struct tty_struct *tty, int timeout)
 				break;
 		}
 	} else {
-		//TODO: determine if there is something similar to USC16C32
-		// 	TXSTATUS_ALL_SENT status
+		/*
+		 * TODO: determine if there is something similar to USC16C32
+		 * 	 TXSTATUS_ALL_SENT status
+		 */
 		while ( info->tx_active && info->tx_enabled) {
 			msleep_interruptible(jiffies_to_msecs(char_time));
 			if (signal_pending(current))
@@ -1106,7 +1105,6 @@ static void wait_until_sent(struct tty_struct *tty, int timeout)
 	}
 
 exit:
-	unlock_kernel();
 	if (debug_level >= DEBUG_LEVEL_INFO)
 		printk("%s(%d):%s wait_until_sent() exit\n",
 			 __FILE__,__LINE__, info->device_name );
@@ -1122,7 +1120,6 @@ static int write_room(struct tty_struct *tty)
 	if (sanity_check(info, tty->name, "write_room"))
 		return 0;
 
-	lock_kernel();
 	if (info->params.mode == MGSL_MODE_HDLC) {
 		ret = (info->tx_active) ? 0 : HDLC_MAX_FRAME_SIZE;
 	} else {
@@ -1130,7 +1127,6 @@ static int write_room(struct tty_struct *tty)
 		if (ret < 0)
 			ret = 0;
 	}
-	unlock_kernel();
 
 	if (debug_level >= DEBUG_LEVEL_INFO)
 		printk("%s(%d):%s write_room()=%d\n",
@@ -1251,7 +1247,7 @@ static void tx_release(struct tty_struct *tty)
  *
  * Return Value:	0 if success, otherwise error code
  */
-static int do_ioctl(struct tty_struct *tty, struct file *file,
+static int ioctl(struct tty_struct *tty, struct file *file,
 		 unsigned int cmd, unsigned long arg)
 {
 	SLMP_INFO *info = tty->driver_data;
@@ -1341,16 +1337,6 @@ static int do_ioctl(struct tty_struct *tty, struct file *file,
 	return 0;
 }
 
-static int ioctl(struct tty_struct *tty, struct file *file,
-		 unsigned int cmd, unsigned long arg)
-{
-	int ret;
-	lock_kernel();
-	ret = do_ioctl(tty, file, cmd, arg);
-	unlock_kernel();
-	return ret;
-}
-
 /*
  * /proc fs routines....
  */
@@ -2883,7 +2869,9 @@ static int get_stats(SLMP_INFO * info, struct mgsl_icount __user *user_icount)
 	if (!user_icount) {
 		memset(&info->icount, 0, sizeof(info->icount));
 	} else {
+		mutex_lock(&info->port.mutex);
 		COPY_TO_USER(err, user_icount, &info->icount, sizeof(struct mgsl_icount));
+		mutex_unlock(&info->port.mutex);
 		if (err)
 			return -EFAULT;
 	}
@@ -2898,7 +2886,9 @@ static int get_params(SLMP_INFO * info, MGSL_PARAMS __user *user_params)
 		printk("%s(%d):%s get_params()\n",
 			 __FILE__,__LINE__, info->device_name);
 
+	mutex_lock(&info->port.mutex);
 	COPY_TO_USER(err,user_params, &info->params, sizeof(MGSL_PARAMS));
+	mutex_unlock(&info->port.mutex);
 	if (err) {
 		if ( debug_level >= DEBUG_LEVEL_INFO )
 			printk( "%s(%d):%s get_params() user buffer copy failed\n",
@@ -2926,11 +2916,13 @@ static int set_params(SLMP_INFO * info, MGSL_PARAMS __user *new_params)
 		return -EFAULT;
 	}
 
+	mutex_lock(&info->port.mutex);
 	spin_lock_irqsave(&info->lock,flags);
 	memcpy(&info->params,&tmp_params,sizeof(MGSL_PARAMS));
 	spin_unlock_irqrestore(&info->lock,flags);
 
  	change_params(info);
+	mutex_unlock(&info->port.mutex);
 
 	return 0;
 }
-- 
1.7.0.4

[PATCH 07/31] cyclades: Kill off BKL usage

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

Use the port mutext for config setting, the rest is locked sufficiently
anyway that the BKL makes no odds.

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/char/cyclades.c |   20 +++++++++-----------
 1 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/drivers/char/cyclades.c b/drivers/char/cyclades.c
index 9824b41..51acfe3 100644
--- a/drivers/char/cyclades.c
+++ b/drivers/char/cyclades.c
@@ -65,7 +65,6 @@
 #include <linux/tty.h>
 #include <linux/tty_flip.h>
 #include <linux/serial.h>
-#include <linux/smp_lock.h>
 #include <linux/major.h>
 #include <linux/string.h>
 #include <linux/fcntl.h>
@@ -1655,7 +1654,6 @@ static void cy_wait_until_sent(struct tty_struct *tty, int timeout)
 		return;		/* Just in case.... */
 
 	orig_jiffies = jiffies;
-	lock_kernel();
 	/*
 	 * Set the check interval to be 1/5 of the estimated time to
 	 * send a single character, and make it at least 1.  The check
@@ -1702,7 +1700,6 @@ static void cy_wait_until_sent(struct tty_struct *tty, int timeout)
 	}
 	/* Run one more char cycle */
 	msleep_interruptible(jiffies_to_msecs(char_time * 5));
-	unlock_kernel();
 #ifdef CY_DEBUG_WAIT_UNTIL_SENT
 	printk(KERN_DEBUG "Clean (jiff=%lu)...done\n", jiffies);
 #endif
@@ -1959,7 +1956,6 @@ static int cy_chars_in_buffer(struct tty_struct *tty)
 		int char_count;
 		__u32 tx_put, tx_get, tx_bufsize;
 
-		lock_kernel();
 		tx_get = readl(&buf_ctrl->tx_get);
 		tx_put = readl(&buf_ctrl->tx_put);
 		tx_bufsize = readl(&buf_ctrl->tx_bufsize);
@@ -1971,7 +1967,6 @@ static int cy_chars_in_buffer(struct tty_struct *tty)
 		printk(KERN_DEBUG "cyc:cy_chars_in_buffer ttyC%d %d\n",
 			info->line, info->xmit_cnt + char_count);
 #endif
-		unlock_kernel();
 		return info->xmit_cnt + char_count;
 	}
 #endif				/* Z_EXT_CHARS_IN_BUFFER */
@@ -2359,17 +2354,22 @@ cy_set_serial_info(struct cyclades_port *info, struct tty_struct *tty,
 		struct serial_struct __user *new_info)
 {
 	struct serial_struct new_serial;
+	int ret;
 
 	if (copy_from_user(&new_serial, new_info, sizeof(new_serial)))
 		return -EFAULT;
 
+	mutex_lock(&info->port.mutex);
 	if (!capable(CAP_SYS_ADMIN)) {
 		if (new_serial.close_delay != info->port.close_delay ||
 				new_serial.baud_base != info->baud ||
 				(new_serial.flags & ASYNC_FLAGS &
 					~ASYNC_USR_MASK) !=
 				(info->port.flags & ASYNC_FLAGS & ~ASYNC_USR_MASK))
+		{
+			mutex_unlock(&info->port.mutex);
 			return -EPERM;
+		}
 		info->port.flags = (info->port.flags & ~ASYNC_USR_MASK) |
 				(new_serial.flags & ASYNC_USR_MASK);
 		info->baud = new_serial.baud_base;
@@ -2392,10 +2392,12 @@ cy_set_serial_info(struct cyclades_port *info, struct tty_struct *tty,
 check_and_exit:
 	if (info->port.flags & ASYNC_INITIALIZED) {
 		cy_set_line_char(info, tty);
-		return 0;
+		ret = 0;
 	} else {
-		return cy_startup(info, tty);
+		ret = cy_startup(info, tty);
 	}
+	mutex_unlock(&info->port.mutex);
+	return ret;
 }				/* set_serial_info */
 
 /*
@@ -2438,7 +2440,6 @@ static int cy_tiocmget(struct tty_struct *tty, struct file *file)
 
 	card = info->card;
 
-	lock_kernel();
 	if (!cy_is_Z(card)) {
 		unsigned long flags;
 		int channel = info->line - card->first_line;
@@ -2478,7 +2479,6 @@ static int cy_tiocmget(struct tty_struct *tty, struct file *file)
 			((lstatus & C_RS_CTS) ? TIOCM_CTS : 0);
 	}
 end:
-	unlock_kernel();
 	return result;
 }				/* cy_tiomget */
 
@@ -2696,7 +2696,6 @@ cy_ioctl(struct tty_struct *tty, struct file *file,
 	printk(KERN_DEBUG "cyc:cy_ioctl ttyC%d, cmd = %x arg = %lx\n",
 		info->line, cmd, arg);
 #endif
-	lock_kernel();
 
 	switch (cmd) {
 	case CYGETMON:
@@ -2817,7 +2816,6 @@ cy_ioctl(struct tty_struct *tty, struct file *file,
 	default:
 		ret_val = -ENOIOCTLCMD;
 	}
-	unlock_kernel();
 
 #ifdef CY_DEBUG_OTHER
 	printk(KERN_DEBUG "cyc:cy_ioctl done\n");
-- 
1.7.0.4

[PATCH 08/31] epca: Kill the big kernel lock

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

The lock is no longer needed for wait until sent paths so this can go

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/char/epca.c |    4 +---
 1 files changed, 1 insertions(+), 3 deletions(-)

diff --git a/drivers/char/epca.c b/drivers/char/epca.c
index 6f5ffe1..d9df46a 100644
--- a/drivers/char/epca.c
+++ b/drivers/char/epca.c
@@ -36,7 +36,7 @@
 #include <linux/ctype.h>
 #include <linux/tty.h>
 #include <linux/tty_flip.h>
-#include <linux/smp_lock.h>
+#include <linux/slab.h>
 #include <linux/ioport.h>
 #include <linux/interrupt.h>
 #include <linux/uaccess.h>
@@ -2105,7 +2105,6 @@ static int pc_ioctl(struct tty_struct *tty, struct file *file,
 		break;
 	case DIGI_SETAW:
 	case DIGI_SETAF:
-		lock_kernel();
 		if (cmd == DIGI_SETAW) {
 			/* Setup an event to indicate when the transmit
 			   buffer empties */
@@ -2118,7 +2117,6 @@ static int pc_ioctl(struct tty_struct *tty, struct file *file,
 			if (tty->ldisc->ops->flush_buffer)
 				tty->ldisc->ops->flush_buffer(tty);
 		}
-		unlock_kernel();
 		/* Fall Thru */
 	case DIGI_SETA:
 		if (copy_from_user(&ch->digiext, argp, sizeof(digi_t)))
-- 
1.7.0.4

[PATCH 09/31] specialix; Kill the BKL

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

Use the port mutex instead

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/char/specialix.c |   11 +++++------
 1 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/drivers/char/specialix.c b/drivers/char/specialix.c
index 2c24fcd..7be456f 100644
--- a/drivers/char/specialix.c
+++ b/drivers/char/specialix.c
@@ -1863,8 +1863,7 @@ static int sx_set_serial_info(struct specialix_port *port,
 		return -EFAULT;
 	}
 
-	lock_kernel();
-
+	mutex_lock(&port->port.mutex);
 	change_speed = ((port->port.flags & ASYNC_SPD_MASK) !=
 			(tmp.flags & ASYNC_SPD_MASK));
 	change_speed |= (tmp.custom_divisor != port->custom_divisor);
@@ -1875,7 +1874,7 @@ static int sx_set_serial_info(struct specialix_port *port,
 		    ((tmp.flags & ~ASYNC_USR_MASK) !=
 		     (port->port.flags & ~ASYNC_USR_MASK))) {
 			func_exit();
-			unlock_kernel();
+			mutex_unlock(&port->port.mutex);
 			return -EPERM;
 		}
 		port->port.flags = ((port->port.flags & ~ASYNC_USR_MASK) |
@@ -1892,7 +1891,7 @@ static int sx_set_serial_info(struct specialix_port *port,
 		sx_change_speed(bp, port);
 
 	func_exit();
-	unlock_kernel();
+	mutex_unlock(&port->port.mutex);
 	return 0;
 }
 
@@ -1906,7 +1905,7 @@ static int sx_get_serial_info(struct specialix_port *port,
 	func_enter();
 
 	memset(&tmp, 0, sizeof(tmp));
-	lock_kernel();
+	mutex_lock(&port->port.mutex);
 	tmp.type = PORT_CIRRUS;
 	tmp.line = port - sx_port;
 	tmp.port = bp->base;
@@ -1917,7 +1916,7 @@ static int sx_get_serial_info(struct specialix_port *port,
 	tmp.closing_wait = port->port.closing_wait * HZ/100;
 	tmp.custom_divisor =  port->custom_divisor;
 	tmp.xmit_fifo_size = CD186x_NFIFO;
-	unlock_kernel();
+	mutex_unlock(&port->port.mutex);
 	if (copy_to_user(retinfo, &tmp, sizeof(tmp))) {
 		func_exit();
 		return -EFAULT;
-- 
1.7.0.4

[PATCH 10/31] synclink: reworking locking a bit

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

Use the port mutex and port lock to fix the various races. The locking
still isn't totally consistent but its better than before. Wants switching
to the port helpers.

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/char/synclink_gt.c |   12 +++++++++++-
 drivers/char/synclinkmp.c  |    9 ++++++++-
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/char/synclink_gt.c b/drivers/char/synclink_gt.c
index d0f81f5..c56b70a 100644
--- a/drivers/char/synclink_gt.c
+++ b/drivers/char/synclink_gt.c
@@ -675,12 +675,14 @@ static int open(struct tty_struct *tty, struct file *filp)
 		goto cleanup;
 	}
 
+	mutex_lock(&info->port.mutex);
 	info->port.tty->low_latency = (info->port.flags & ASYNC_LOW_LATENCY) ? 1 : 0;
 
 	spin_lock_irqsave(&info->netlock, flags);
 	if (info->netcount) {
 		retval = -EBUSY;
 		spin_unlock_irqrestore(&info->netlock, flags);
+		mutex_unlock(&info->port.mutex);
 		goto cleanup;
 	}
 	info->port.count++;
@@ -692,7 +694,7 @@ static int open(struct tty_struct *tty, struct file *filp)
 		if (retval < 0)
 			goto cleanup;
 	}
-
+	mutex_unlock(&info->port.mutex);
 	retval = block_til_ready(tty, filp, info);
 	if (retval) {
 		DBGINFO(("%s block_til_ready rc=%d\n", info->device_name, retval));
@@ -724,12 +726,14 @@ static void close(struct tty_struct *tty, struct file *filp)
 	if (tty_port_close_start(&info->port, tty, filp) == 0)
 		goto cleanup;
 
+	mutex_lock(&info->port.mutex);
  	if (info->port.flags & ASYNC_INITIALIZED)
  		wait_until_sent(tty, info->timeout);
 	flush_buffer(tty);
 	tty_ldisc_flush(tty);
 
 	shutdown(info);
+	mutex_unlock(&info->port.mutex);
 
 	tty_port_close_end(&info->port, tty);
 	info->port.tty = NULL;
@@ -740,17 +744,23 @@ cleanup:
 static void hangup(struct tty_struct *tty)
 {
 	struct slgt_info *info = tty->driver_data;
+	unsigned long flags;
 
 	if (sanity_check(info, tty->name, "hangup"))
 		return;
 	DBGINFO(("%s hangup\n", info->device_name));
 
 	flush_buffer(tty);
+
+	mutex_lock(&info->port.mutex);
 	shutdown(info);
 
+	spin_lock_irqsave(&info->port.lock, flags);
 	info->port.count = 0;
 	info->port.flags &= ~ASYNC_NORMAL_ACTIVE;
 	info->port.tty = NULL;
+	spin_unlock_irqrestore(&info->port.lock, flags);
+	mutex_unlock(&info->port.mutex);
 
 	wake_up_interruptible(&info->port.open_wait);
 }
diff --git a/drivers/char/synclinkmp.c b/drivers/char/synclinkmp.c
index 8da976b..cfa581e 100644
--- a/drivers/char/synclinkmp.c
+++ b/drivers/char/synclinkmp.c
@@ -812,13 +812,15 @@ static void close(struct tty_struct *tty, struct file *filp)
 
 	if (tty_port_close_start(&info->port, tty, filp) == 0)
 		goto cleanup;
-		
+
+	mutex_lock(&info->port.mutex);		
  	if (info->port.flags & ASYNC_INITIALIZED)
  		wait_until_sent(tty, info->timeout);
 
 	flush_buffer(tty);
 	tty_ldisc_flush(tty);
 	shutdown(info);
+	mutex_unlock(&info->port.mutex);		
 
 	tty_port_close_end(&info->port, tty);
 	info->port.tty = NULL;
@@ -834,6 +836,7 @@ cleanup:
 static void hangup(struct tty_struct *tty)
 {
 	SLMP_INFO *info = tty->driver_data;
+	unsigned long flags;
 
 	if (debug_level >= DEBUG_LEVEL_INFO)
 		printk("%s(%d):%s hangup()\n",
@@ -842,12 +845,16 @@ static void hangup(struct tty_struct *tty)
 	if (sanity_check(info, tty->name, "hangup"))
 		return;
 
+	mutex_lock(&info->port.mutex);		
 	flush_buffer(tty);
 	shutdown(info);
 
+	spin_lock_irqsave(&info->port.lock, flags);
 	info->port.count = 0;
 	info->port.flags &= ~ASYNC_NORMAL_ACTIVE;
 	info->port.tty = NULL;
+	spin_unlock_irqrestore(&info->port.lock, flags);
+	mutex_unlock(&info->port.mutex);		
 
 	wake_up_interruptible(&info->port.open_wait);
 }
-- 
1.7.0.4

[PATCH 11/31] tty: serial - fix various misuses/mishandlings of port->tty

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

Make it robust against hang up events. In most cases we can do this simply
by passing the right things in the first place.

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/serial/serial_core.c |  109 +++++++++++++++++++++++-------------------
 1 files changed, 60 insertions(+), 49 deletions(-)

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 7f28307..12ee7e0 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -58,7 +58,7 @@ static struct lock_class_key port_lock_key;
 #define uart_console(port)	(0)
 #endif
 
-static void uart_change_speed(struct uart_state *state,
+static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
 					struct ktermios *old_termios);
 static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
 static void uart_change_pm(struct uart_state *state, int pm_state);
@@ -137,7 +137,7 @@ uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
  * Startup the port.  This will be called once per open.  All calls
  * will be serialised by the per-port mutex.
  */
-static int uart_startup(struct uart_state *state, int init_hw)
+static int uart_startup(struct tty_struct *tty, struct uart_state *state, int init_hw)
 {
 	struct uart_port *uport = state->uart_port;
 	struct tty_port *port = &state->port;
@@ -152,7 +152,7 @@ static int uart_startup(struct uart_state *state, int init_hw)
 	 * once we have successfully opened the port.  Also set
 	 * up the tty->alt_speed kludge
 	 */
-	set_bit(TTY_IO_ERROR, &port->tty->flags);
+	set_bit(TTY_IO_ERROR, &tty->flags);
 
 	if (uport->type == PORT_UNKNOWN)
 		return 0;
@@ -177,26 +177,26 @@ static int uart_startup(struct uart_state *state, int init_hw)
 			/*
 			 * Initialise the hardware port settings.
 			 */
-			uart_change_speed(state, NULL);
+			uart_change_speed(tty, state, NULL);
 
 			/*
 			 * Setup the RTS and DTR signals once the
 			 * port is open and ready to respond.
 			 */
-			if (port->tty->termios->c_cflag & CBAUD)
+			if (tty->termios->c_cflag & CBAUD)
 				uart_set_mctrl(uport, TIOCM_RTS | TIOCM_DTR);
 		}
 
 		if (port->flags & ASYNC_CTS_FLOW) {
 			spin_lock_irq(&uport->lock);
 			if (!(uport->ops->get_mctrl(uport) & TIOCM_CTS))
-				port->tty->hw_stopped = 1;
+				tty->hw_stopped = 1;
 			spin_unlock_irq(&uport->lock);
 		}
 
 		set_bit(ASYNCB_INITIALIZED, &port->flags);
 
-		clear_bit(TTY_IO_ERROR, &port->tty->flags);
+		clear_bit(TTY_IO_ERROR, &tty->flags);
 	}
 
 	if (retval && capable(CAP_SYS_ADMIN))
@@ -210,11 +210,10 @@ static int uart_startup(struct uart_state *state, int init_hw)
  * DTR is dropped if the hangup on close termio flag is on.  Calls to
  * uart_shutdown are serialised by the per-port semaphore.
  */
-static void uart_shutdown(struct uart_state *state)
+static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
 {
 	struct uart_port *uport = state->uart_port;
 	struct tty_port *port = &state->port;
-	struct tty_struct *tty = port->tty;
 
 	/*
 	 * Set the TTY IO error marker
@@ -430,11 +429,10 @@ uart_get_divisor(struct uart_port *port, unsigned int baud)
 EXPORT_SYMBOL(uart_get_divisor);
 
 /* FIXME: Consistent locking policy */
-static void
-uart_change_speed(struct uart_state *state, struct ktermios *old_termios)
+static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
+					struct ktermios *old_termios)
 {
 	struct tty_port *port = &state->port;
-	struct tty_struct *tty = port->tty;
 	struct uart_port *uport = state->uart_port;
 	struct ktermios *termios;
 
@@ -463,8 +461,8 @@ uart_change_speed(struct uart_state *state, struct ktermios *old_termios)
 	uport->ops->set_termios(uport, termios, old_termios);
 }
 
-static inline int
-__uart_put_char(struct uart_port *port, struct circ_buf *circ, unsigned char c)
+static inline int __uart_put_char(struct uart_port *port,
+				struct circ_buf *circ, unsigned char c)
 {
 	unsigned long flags;
 	int ret = 0;
@@ -494,8 +492,8 @@ static void uart_flush_chars(struct tty_struct *tty)
 	uart_start(tty);
 }
 
-static int
-uart_write(struct tty_struct *tty, const unsigned char *buf, int count)
+static int uart_write(struct tty_struct *tty,
+					const unsigned char *buf, int count)
 {
 	struct uart_state *state = tty->driver_data;
 	struct uart_port *port;
@@ -675,7 +673,7 @@ static int uart_get_info(struct uart_state *state,
 	return 0;
 }
 
-static int uart_set_info(struct uart_state *state,
+static int uart_set_info(struct tty_struct *tty, struct uart_state *state,
 			 struct serial_struct __user *newinfo)
 {
 	struct serial_struct new_serial;
@@ -770,7 +768,7 @@ static int uart_set_info(struct uart_state *state,
 		 * We need to shutdown the serial port at the old
 		 * port/type/irq combination.
 		 */
-		uart_shutdown(state);
+		uart_shutdown(tty, state);
 	}
 
 	if (change_port) {
@@ -869,25 +867,27 @@ static int uart_set_info(struct uart_state *state,
 				       "is deprecated.\n", current->comm,
 				       tty_name(port->tty, buf));
 			}
-			uart_change_speed(state, NULL);
+			uart_change_speed(tty, state, NULL);
 		}
 	} else
-		retval = uart_startup(state, 1);
+		retval = uart_startup(tty, state, 1);
  exit:
 	mutex_unlock(&port->mutex);
 	return retval;
 }
 
-
-/*
- * uart_get_lsr_info - get line status register info.
- * Note: uart_ioctl protects us against hangups.
+/**
+ *	uart_get_lsr_info	-	get line status register info
+ *	@tty: tty associated with the UART
+ *	@state: UART being queried
+ *	@value: returned modem value
+ *
+ *	Note: uart_ioctl protects us against hangups.
  */
-static int uart_get_lsr_info(struct uart_state *state,
-			     unsigned int __user *value)
+static int uart_get_lsr_info(struct tty_struct *tty,
+			struct uart_state *state, unsigned int __user *value)
 {
 	struct uart_port *uport = state->uart_port;
-	struct tty_port *port = &state->port;
 	unsigned int result;
 
 	result = uport->ops->tx_empty(uport);
@@ -900,7 +900,7 @@ static int uart_get_lsr_info(struct uart_state *state,
 	 */
 	if (uport->x_char ||
 	    ((uart_circ_chars_pending(&state->xmit) > 0) &&
-	     !port->tty->stopped && !port->tty->hw_stopped))
+	     !tty->stopped && !tty->hw_stopped))
 		result &= ~TIOCSER_TEMT;
 
 	return put_user(result, value);
@@ -961,7 +961,7 @@ static int uart_break_ctl(struct tty_struct *tty, int break_state)
 	return 0;
 }
 
-static int uart_do_autoconfig(struct uart_state *state)
+static int uart_do_autoconfig(struct tty_struct *tty,struct uart_state *state)
 {
 	struct uart_port *uport = state->uart_port;
 	struct tty_port *port = &state->port;
@@ -980,7 +980,7 @@ static int uart_do_autoconfig(struct uart_state *state)
 
 	ret = -EBUSY;
 	if (tty_port_users(port) == 1) {
-		uart_shutdown(state);
+		uart_shutdown(tty, state);
 
 		/*
 		 * If we already have a port type configured,
@@ -999,7 +999,7 @@ static int uart_do_autoconfig(struct uart_state *state)
 		 */
 		uport->ops->config_port(uport, flags);
 
-		ret = uart_startup(state, 1);
+		ret = uart_startup(tty, state, 1);
 	}
 	mutex_unlock(&port->mutex);
 	return ret;
@@ -1122,11 +1122,11 @@ uart_ioctl(struct tty_struct *tty, struct file *filp, unsigned int cmd,
 		break;
 
 	case TIOCSSERIAL:
-		ret = uart_set_info(state, uarg);
+		ret = uart_set_info(tty, state, uarg);
 		break;
 
 	case TIOCSERCONFIG:
-		ret = uart_do_autoconfig(state);
+		ret = uart_do_autoconfig(tty, state);
 		break;
 
 	case TIOCSERGWILD: /* obsolete */
@@ -1172,7 +1172,7 @@ uart_ioctl(struct tty_struct *tty, struct file *filp, unsigned int cmd,
 	 */
 	switch (cmd) {
 	case TIOCSERGETLSR: /* Get line status register */
-		ret = uart_get_lsr_info(state, uarg);
+		ret = uart_get_lsr_info(tty, state, uarg);
 		break;
 
 	default: {
@@ -1219,7 +1219,7 @@ static void uart_set_termios(struct tty_struct *tty,
 		return;
 	}
 
-	uart_change_speed(state, old_termios);
+	uart_change_speed(tty, state, old_termios);
 
 	/* Handle transition to B0 status */
 	if ((old_termios->c_cflag & CBAUD) && !(cflag & CBAUD))
@@ -1335,7 +1335,7 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
 		uart_wait_until_sent(tty, uport->timeout);
 	}
 
-	uart_shutdown(state);
+	uart_shutdown(tty, state);
 	uart_flush_buffer(tty);
 
 	tty_ldisc_flush(tty);
@@ -1436,7 +1436,7 @@ static void uart_hangup(struct tty_struct *tty)
 	mutex_lock(&port->mutex);
 	if (port->flags & ASYNC_NORMAL_ACTIVE) {
 		uart_flush_buffer(tty);
-		uart_shutdown(state);
+		uart_shutdown(tty, state);
 		port->count = 0;
 		clear_bit(ASYNCB_NORMAL_ACTIVE, &port->flags);
 		tty_port_tty_set(port, NULL);
@@ -1446,15 +1446,19 @@ static void uart_hangup(struct tty_struct *tty)
 	mutex_unlock(&port->mutex);
 }
 
-/*
- * Copy across the serial console cflag setting into the termios settings
- * for the initial open of the port.  This allows continuity between the
- * kernel settings, and the settings init adopts when it opens the port
- * for the first time.
+/**
+ *	uart_update_termios	-	update the terminal hw settings
+ *	@tty: tty associated with UART
+ *	@state: UART to update
+ *
+ *	Copy across the serial console cflag setting into the termios settings
+ *	for the initial open of the port.  This allows continuity between the
+ *	kernel settings, and the settings init adopts when it opens the port
+ *	for the first time.
  */
-static void uart_update_termios(struct uart_state *state)
+static void uart_update_termios(struct tty_struct *tty,
+						struct uart_state *state)
 {
-	struct tty_struct *tty = state->port.tty;
 	struct uart_port *port = state->uart_port;
 
 	if (uart_console(port) && port->cons->cflag) {
@@ -1471,7 +1475,7 @@ static void uart_update_termios(struct uart_state *state)
 		/*
 		 * Make termios settings take effect.
 		 */
-		uart_change_speed(state, NULL);
+		uart_change_speed(tty, state, NULL);
 
 		/*
 		 * And finally enable the RTS and DTR signals.
@@ -1668,7 +1672,7 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
 	/*
 	 * Start up the serial port.
 	 */
-	retval = uart_startup(state, 0);
+	retval = uart_startup(tty, state, 0);
 
 	/*
 	 * If we succeeded, wait until the port is ready.
@@ -1683,7 +1687,7 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
 	if (retval == 0 && !(port->flags & ASYNC_NORMAL_ACTIVE)) {
 		set_bit(ASYNCB_NORMAL_ACTIVE, &port->flags);
 
-		uart_update_termios(state);
+		uart_update_termios(tty, state);
 	}
 
 fail:
@@ -2010,9 +2014,13 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
 	struct tty_port *port = &state->port;
 	struct device *tty_dev;
 	struct uart_match match = {uport, drv};
+	struct tty_struct *tty;
 
 	mutex_lock(&port->mutex);
 
+	/* Must be inside the mutex lock until we convert to tty_port */
+	tty = port->tty;
+
 	tty_dev = device_find_child(uport->dev, &match, serial_match_port);
 	if (device_may_wakeup(tty_dev)) {
 		enable_irq_wake(uport->irq);
@@ -2105,9 +2113,12 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
 		ops->set_mctrl(uport, 0);
 		spin_unlock_irq(&uport->lock);
 		if (console_suspend_enabled || !uart_console(uport)) {
+			/* Protected by port mutex for now */
+			struct tty_struct *tty = port->tty;
 			ret = ops->startup(uport);
 			if (ret == 0) {
-				uart_change_speed(state, NULL);
+				if (tty)
+					uart_change_speed(tty, state, NULL);
 				spin_lock_irq(&uport->lock);
 				ops->set_mctrl(uport, uport->mctrl);
 				ops->start_tx(uport);
@@ -2119,7 +2130,7 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
 				 * Clear the "initialized" flag so we won't try
 				 * to call the low level drivers shutdown method.
 				 */
-				uart_shutdown(state);
+				uart_shutdown(tty, state);
 			}
 		}
 
-- 
1.7.0.4

[PATCH 12/31] tty: serial - fix tty back references in termios

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

One or two drivers go poking back into the tty from the termios setting
routine in unsafe ways. We don't need to pass the tty down because the
[ab]users are just using it to get at things they can get at anyway.

This leaves low_latency setting to sort out along with set_ldisc use.

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/serial/21285.c       |   10 +++-------
 drivers/serial/imx.c         |   10 ++++------
 drivers/serial/ioc3_serial.c |    9 +++++----
 drivers/serial/ioc4_serial.c |    9 +++++----
 drivers/serial/max3100.c     |    7 ++-----
 5 files changed, 19 insertions(+), 26 deletions(-)

diff --git a/drivers/serial/21285.c b/drivers/serial/21285.c
index 8681f13..d89aa38 100644
--- a/drivers/serial/21285.c
+++ b/drivers/serial/21285.c
@@ -216,7 +216,7 @@ serial21285_set_termios(struct uart_port *port, struct ktermios *termios,
 			struct ktermios *old)
 {
 	unsigned long flags;
-	unsigned int baud, quot, h_lcr;
+	unsigned int baud, quot, h_lcr, b;
 
 	/*
 	 * We don't support modem control lines.
@@ -234,12 +234,8 @@ serial21285_set_termios(struct uart_port *port, struct ktermios *termios,
 	 */
 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16); 
 	quot = uart_get_divisor(port, baud);
-
-	if (port->state && port->state->port.tty) {
-		struct tty_struct *tty = port->state->port.tty;
-		unsigned int b = port->uartclk / (16 * quot);
-		tty_encode_baud_rate(tty, b, b);
-	}
+	b = port->uartclk / (16 * quot);
+	tty_termios_encode_baud_rate(termios, b, b);
 
 	switch (termios->c_cflag & CSIZE) {
 	case CS5:
diff --git a/drivers/serial/imx.c b/drivers/serial/imx.c
index eacb588..66ecc7a 100644
--- a/drivers/serial/imx.c
+++ b/drivers/serial/imx.c
@@ -909,13 +909,11 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios,
 	rational_best_approximation(16 * div * baud, sport->port.uartclk,
 		1 << 16, 1 << 16, &num, &denom);
 
-	if (port->state && port->state->port.tty) {
-		tdiv64 = sport->port.uartclk;
-		tdiv64 *= num;
-		do_div(tdiv64, denom * 16 * div);
-		tty_encode_baud_rate(sport->port.state->port.tty,
+	tdiv64 = sport->port.uartclk;
+	tdiv64 *= num;
+	do_div(tdiv64, denom * 16 * div);
+	tty_termios_encode_baud_rate(termios,
 				(speed_t)tdiv64, (speed_t)tdiv64);
-	}
 
 	num -= 1;
 	denom -= 1;
diff --git a/drivers/serial/ioc3_serial.c b/drivers/serial/ioc3_serial.c
index f164ba4..bd2e9e6 100644
--- a/drivers/serial/ioc3_serial.c
+++ b/drivers/serial/ioc3_serial.c
@@ -954,12 +954,13 @@ ioc3_change_speed(struct uart_port *the_port,
 		  struct ktermios *new_termios, struct ktermios *old_termios)
 {
 	struct ioc3_port *port = get_ioc3_port(the_port);
-	unsigned int cflag;
+	unsigned int cflag, iflag;
 	int baud;
 	int new_parity = 0, new_parity_enable = 0, new_stop = 0, new_data = 8;
 	struct uart_state *state = the_port->state;
 
 	cflag = new_termios->c_cflag;
+	iflag = new_termios->c_iflag;
 
 	switch (cflag & CSIZE) {
 	case CS5:
@@ -1000,12 +1001,12 @@ ioc3_change_speed(struct uart_port *the_port,
 
 	state->port.tty->low_latency = 1;
 
-	if (I_IGNPAR(state->port.tty))
+	if (iflag & IGNPAR))
 		the_port->ignore_status_mask &= ~(N_PARITY_ERROR
 						  | N_FRAMING_ERROR);
-	if (I_IGNBRK(state->port.tty)) {
+	if (iflag & IGNBRK) {
 		the_port->ignore_status_mask &= ~N_BREAK;
-		if (I_IGNPAR(state->port.tty))
+		if (iflag & IGNPAR)
 			the_port->ignore_status_mask &= ~N_OVERRUN_ERROR;
 	}
 	if (!(cflag & CREAD)) {
diff --git a/drivers/serial/ioc4_serial.c b/drivers/serial/ioc4_serial.c
index 8ad28fc..2c30023 100644
--- a/drivers/serial/ioc4_serial.c
+++ b/drivers/serial/ioc4_serial.c
@@ -1685,11 +1685,12 @@ ioc4_change_speed(struct uart_port *the_port,
 {
 	struct ioc4_port *port = get_ioc4_port(the_port, 0);
 	int baud, bits;
-	unsigned cflag;
+	unsigned cflag, iflag;
 	int new_parity = 0, new_parity_enable = 0, new_stop = 0, new_data = 8;
 	struct uart_state *state = the_port->state;
 
 	cflag = new_termios->c_cflag;
+	iflag = new_termios->c_iflag;
 
 	switch (cflag & CSIZE) {
 	case CS5:
@@ -1741,12 +1742,12 @@ ioc4_change_speed(struct uart_port *the_port,
 
 	state->port.tty->low_latency = 1;
 
-	if (I_IGNPAR(state->port.tty))
+	if (iflag & IGNPAR)
 		the_port->ignore_status_mask &= ~(N_PARITY_ERROR
 						| N_FRAMING_ERROR);
-	if (I_IGNBRK(state->port.tty)) {
+	if (iflag & IGNBRK) {
 		the_port->ignore_status_mask &= ~N_BREAK;
-		if (I_IGNPAR(state->port.tty))
+		if (iflag & IGNPAR))
 			the_port->ignore_status_mask &= ~N_OVERRUN_ERROR;
 	}
 	if (!(cflag & CREAD)) {
diff --git a/drivers/serial/max3100.c b/drivers/serial/max3100.c
index 3351c3b..beb1afa 100644
--- a/drivers/serial/max3100.c
+++ b/drivers/serial/max3100.c
@@ -430,17 +430,14 @@ max3100_set_termios(struct uart_port *port, struct ktermios *termios,
 	int baud = 0;
 	unsigned cflag;
 	u32 param_new, param_mask, parity = 0;
-	struct tty_struct *tty = s->port.state->port.tty;
 
 	dev_dbg(&s->spi->dev, "%s\n", __func__);
-	if (!tty)
-		return;
 
 	cflag = termios->c_cflag;
 	param_new = 0;
 	param_mask = 0;
 
-	baud = tty_get_baud_rate(tty);
+	baud = tty_termios_baud_rate(termios);
 	param_new = s->conf & MAX3100_BAUD;
 	switch (baud) {
 	case 300:
@@ -485,7 +482,7 @@ max3100_set_termios(struct uart_port *port, struct ktermios *termios,
 	default:
 		baud = s->baud;
 	}
-	tty_encode_baud_rate(tty, baud, baud);
+	tty_termios_encode_baud_rate(termios, baud, baud);
 	s->baud = baud;
 	param_mask |= MAX3100_BAUD;
 
-- 
1.7.0.4

Re: [PATCH 12/31] tty: serial - fix tty back references in termios

[Tony Luck]

A couple of build breaks in linux-next (tag: next-20100617)

drivers/serial/ioc4_serial.c:1750: error: expected statement before ‘)’ token

Would have a similar one for ioc3_serial.c if my .config included it.

On Tue, Jun 1, 2010 at 1:52 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> diff --git a/drivers/serial/ioc3_serial.c b/drivers/serial/ioc3_serial.c
> index f164ba4..bd2e9e6 100644
> --- a/drivers/serial/ioc3_serial.c
> +++ b/drivers/serial/ioc3_serial.c
 ...
> -       if (I_IGNPAR(state->port.tty))
> +       if (iflag & IGNPAR))

Can we have matching numbers of "(" and ")" here please.

> diff --git a/drivers/serial/ioc4_serial.c b/drivers/serial/ioc4_serial.c
> index 8ad28fc..2c30023 100644
> --- a/drivers/serial/ioc4_serial.c
> +++ b/drivers/serial/ioc4_serial.c
 ..
.-               if (I_IGNPAR(state->port.tty))
+               if (iflag & IGNPAR))

Same here.

-Tony

Re: [PATCH 12/31] tty: serial - fix tty back references in termios

[Greg KH]

On Thu, Jun 17, 2010 at 11:50:57AM -0700, Tony Luck wrote:
> A couple of build breaks in linux-next (tag: next-20100617)
> 
> drivers/serial/ioc4_serial.c:1750: error: expected statement before ‘)’ token
> 
> Would have a similar one for ioc3_serial.c if my .config included it.
> 
> On Tue, Jun 1, 2010 at 1:52 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> > diff --git a/drivers/serial/ioc3_serial.c b/drivers/serial/ioc3_serial.c
> > index f164ba4..bd2e9e6 100644
> > --- a/drivers/serial/ioc3_serial.c
> > +++ b/drivers/serial/ioc3_serial.c
>  ...
> > -       if (I_IGNPAR(state->port.tty))
> > +       if (iflag & IGNPAR))
> 
> Can we have matching numbers of "(" and ")" here please.
> 
> > diff --git a/drivers/serial/ioc4_serial.c b/drivers/serial/ioc4_serial.c
> > index 8ad28fc..2c30023 100644
> > --- a/drivers/serial/ioc4_serial.c
> > +++ b/drivers/serial/ioc4_serial.c
>  ..
> .-               if (I_IGNPAR(state->port.tty))
> +               if (iflag & IGNPAR))
> 
> Same here.

I've fixed these up in my tree so the next linux-next will contain the
correct ones.

thanks,

greg k-h

[PATCH 13/31] tty: serial - fix tty referencing in set_ldisc

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

Pass down the ldisc number so that the drivers don't have to peek into the
tty object themselves. This lets us get rid of another case of back referencing
port to tty which we don't want (because of races versus hangup/close).

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/serial/bfin_5xx.c    |    7 ++-----
 drivers/serial/serial_core.c |    2 +-
 include/linux/serial_core.h  |    2 +-
 3 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/serial/bfin_5xx.c b/drivers/serial/bfin_5xx.c
index 96f7e74..e0d25ca 100644
--- a/drivers/serial/bfin_5xx.c
+++ b/drivers/serial/bfin_5xx.c
@@ -952,15 +952,12 @@ bfin_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
  * Enable the IrDA function if tty->ldisc.num is N_IRDA.
  * In other cases, disable IrDA function.
  */
-static void bfin_serial_set_ldisc(struct uart_port *port)
+static void bfin_serial_set_ldisc(struct uart_port *port, int ld)
 {
 	int line = port->line;
 	unsigned short val;
 
-	if (line >= port->state->port.tty->driver->num)
-		return;
-
-	switch (port->state->port.tty->termios->c_line) {
+	switch (ld) {
 	case N_IRDA:
 		val = UART_GET_GCTL(&bfin_serial_ports[line]);
 		val |= (IREN | RPOLC);
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 12ee7e0..570dca2 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1194,7 +1194,7 @@ static void uart_set_ldisc(struct tty_struct *tty)
 	struct uart_port *uport = state->uart_port;
 
 	if (uport->ops->set_ldisc)
-		uport->ops->set_ldisc(uport);
+		uport->ops->set_ldisc(uport, tty->termios->c_line);
 }
 
 static void uart_set_termios(struct tty_struct *tty,
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index f10db6e..3292816 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -220,7 +220,7 @@ struct uart_ops {
 	void		(*flush_buffer)(struct uart_port *);
 	void		(*set_termios)(struct uart_port *, struct ktermios *new,
 				       struct ktermios *old);
-	void		(*set_ldisc)(struct uart_port *);
+	void		(*set_ldisc)(struct uart_port *, int new);
 	void		(*pm)(struct uart_port *, unsigned int state,
 			      unsigned int oldstate);
 	int		(*set_wake)(struct uart_port *, unsigned int state);
-- 
1.7.0.4

[PATCH 14/31] vc: Locking clean up

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

The virtual console layer uses the BKL for various things that don't really
need it. Clean them out.

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/char/selection.c |    4 ++++
 drivers/char/vt.c        |    7 ++++---
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/char/selection.c b/drivers/char/selection.c
index f97b9e8..6e79340 100644
--- a/drivers/char/selection.c
+++ b/drivers/char/selection.c
@@ -26,6 +26,7 @@
 #include <linux/selection.h>
 #include <linux/tiocl.h>
 #include <linux/console.h>
+#include <linux/smp_lock.h>
 
 /* Don't take this from <ctype.h>: 011-015 on the screen aren't spaces */
 #define isspace(c)	((c) == ' ')
@@ -312,6 +313,8 @@ int paste_selection(struct tty_struct *tty)
 	struct  tty_ldisc *ld;
 	DECLARE_WAITQUEUE(wait, current);
 
+	lock_kernel();
+
 	acquire_console_sem();
 	poke_blanked_console();
 	release_console_sem();
@@ -335,5 +338,6 @@ int paste_selection(struct tty_struct *tty)
 	__set_current_state(TASK_RUNNING);
 
 	tty_ldisc_deref(ld);
+	unlock_kernel();
 	return 0;
 }
diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 7cdb6ee..9f42b1f 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -280,8 +280,12 @@ static inline unsigned short *screenpos(struct vc_data *vc, int offset, int view
 	return p;
 }
 
+/* Called  from the keyboard irq path.. */
 static inline void scrolldelta(int lines)
 {
+	/* FIXME */
+	/* scrolldelta needs some kind of consistency lock, but the BKL was
+	   and still is not protecting versus the scheduled back end */
 	scrollback_delta += lines;
 	schedule_console_callback();
 }
@@ -2604,8 +2608,6 @@ int tioclinux(struct tty_struct *tty, unsigned long arg)
 		return -EFAULT;
 	ret = 0;
 
-	lock_kernel();
-
 	switch (type)
 	{
 		case TIOCL_SETSEL:
@@ -2680,7 +2682,6 @@ int tioclinux(struct tty_struct *tty, unsigned long arg)
 			ret = -EINVAL;
 			break;
 	}
-	unlock_kernel();
 	return ret;
 }
 
-- 
1.7.0.4

[PATCH 15/31] tty: Make vt's have a tty_port

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

The vt layer isn't safely handling reference counts to tty object on the input
side. Add a tty port structure to the vt layer in order to implement this using
the standard helpers.

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/char/vt.c              |    2 ++
 include/linux/console_struct.h |    2 ++
 2 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 9f42b1f..8c77ecb 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -772,6 +772,7 @@ int vc_allocate(unsigned int currcons)	/* return 0 on success */
 	    if (!vc)
 		return -ENOMEM;
 	    vc_cons[currcons].d = vc;
+	    tty_port_init(&vc->port);
 	    INIT_WORK(&vc_cons[currcons].SAK_work, vc_SAK);
 	    visual_init(vc, currcons, 1);
 	    if (!*vc->vc_uni_pagedir_loc)
@@ -2909,6 +2910,7 @@ static int __init con_init(void)
 	for (currcons = 0; currcons < MIN_NR_CONSOLES; currcons++) {
 		vc_cons[currcons].d = vc = kzalloc(sizeof(struct vc_data), GFP_NOWAIT);
 		INIT_WORK(&vc_cons[currcons].SAK_work, vc_SAK);
+		tty_port_init(&vc->port);
 		visual_init(vc, currcons, 1);
 		vc->vc_screenbuf = kzalloc(vc->vc_screenbuf_size, GFP_NOWAIT);
 		vc_init(vc, vc->vc_rows, vc->vc_cols,
diff --git a/include/linux/console_struct.h b/include/linux/console_struct.h
index 38fe59d..57e83f1 100644
--- a/include/linux/console_struct.h
+++ b/include/linux/console_struct.h
@@ -21,6 +21,8 @@ struct vt_struct;
 #define NPAR 16
 
 struct vc_data {
+	struct tty_port port;			/* Upper level data */
+
 	unsigned short	vc_num;			/* Console number */
 	unsigned int	vc_cols;		/* [#] Console size */
 	unsigned int	vc_rows;
-- 
1.7.0.4

[PATCH 16/31] tty: Move the vt_tty field from the vc_data into the standard tty_port

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

This takes all the tty references through the expected interface points so
we can refcount them.

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/char/keyboard.c        |   10 +++++-----
 drivers/char/vt.c              |   10 +++++-----
 drivers/char/vt_ioctl.c        |    2 +-
 include/linux/console_struct.h |    1 -
 4 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/drivers/char/keyboard.c b/drivers/char/keyboard.c
index 54109dc..ec733f1 100644
--- a/drivers/char/keyboard.c
+++ b/drivers/char/keyboard.c
@@ -299,7 +299,7 @@ int kbd_rate(struct kbd_repeat *rep)
  */
 static void put_queue(struct vc_data *vc, int ch)
 {
-	struct tty_struct *tty = vc->vc_tty;
+	struct tty_struct *tty = vc->port.tty;
 
 	if (tty) {
 		tty_insert_flip_char(tty, ch, 0);
@@ -309,7 +309,7 @@ static void put_queue(struct vc_data *vc, int ch)
 
 static void puts_queue(struct vc_data *vc, char *cp)
 {
-	struct tty_struct *tty = vc->vc_tty;
+	struct tty_struct *tty = vc->port.tty;
 
 	if (!tty)
 		return;
@@ -485,7 +485,7 @@ static void fn_show_ptregs(struct vc_data *vc)
 
 static void fn_hold(struct vc_data *vc)
 {
-	struct tty_struct *tty = vc->vc_tty;
+	struct tty_struct *tty = vc->port.tty;
 
 	if (rep || !tty)
 		return;
@@ -563,7 +563,7 @@ static void fn_inc_console(struct vc_data *vc)
 
 static void fn_send_intr(struct vc_data *vc)
 {
-	struct tty_struct *tty = vc->vc_tty;
+	struct tty_struct *tty = vc->port.tty;
 
 	if (!tty)
 		return;
@@ -1162,7 +1162,7 @@ static void kbd_keycode(unsigned int keycode, int down, int hw_raw)
 	struct keyboard_notifier_param param = { .vc = vc, .value = keycode, .down = down };
 	int rc;
 
-	tty = vc->vc_tty;
+	tty = vc->port.tty;
 
 	if (tty && (!tty->driver_data)) {
 		/* No driver data? Strange. Okay we fix it then. */
diff --git a/drivers/char/vt.c b/drivers/char/vt.c
index 8c77ecb..2f50056 100644
--- a/drivers/char/vt.c
+++ b/drivers/char/vt.c
@@ -961,12 +961,12 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
  *	Resize a virtual console as seen from the console end of things. We
  *	use the common vc_do_resize methods to update the structures. The
  *	caller must hold the console sem to protect console internals and
- *	vc->vc_tty
+ *	vc->port.tty
  */
 
 int vc_resize(struct vc_data *vc, unsigned int cols, unsigned int rows)
 {
-	return vc_do_resize(vc->vc_tty, vc, cols, rows);
+	return vc_do_resize(vc->port.tty, vc, cols, rows);
 }
 
 /**
@@ -2795,12 +2795,12 @@ static int con_open(struct tty_struct *tty, struct file *filp)
 			struct vc_data *vc = vc_cons[currcons].d;
 
 			/* Still being freed */
-			if (vc->vc_tty) {
+			if (vc->port.tty) {
 				release_console_sem();
 				return -ERESTARTSYS;
 			}
 			tty->driver_data = vc;
-			vc->vc_tty = tty;
+			vc->port.tty = tty;
 
 			if (!tty->winsize.ws_row && !tty->winsize.ws_col) {
 				tty->winsize.ws_row = vc_cons[currcons].d->vc_rows;
@@ -2828,7 +2828,7 @@ static void con_shutdown(struct tty_struct *tty)
 	struct vc_data *vc = tty->driver_data;
 	BUG_ON(vc == NULL);
 	acquire_console_sem();
-	vc->vc_tty = NULL;
+	vc->port.tty = NULL;
 	release_console_sem();
 	tty_shutdown(tty);
 }
diff --git a/drivers/char/vt_ioctl.c b/drivers/char/vt_ioctl.c
index 6aa1028..625f77d 100644
--- a/drivers/char/vt_ioctl.c
+++ b/drivers/char/vt_ioctl.c
@@ -1367,7 +1367,7 @@ void vc_SAK(struct work_struct *work)
 	acquire_console_sem();
 	vc = vc_con->d;
 	if (vc) {
-		tty = vc->vc_tty;
+		tty = vc->port.tty;
 		/*
 		 * SAK should also work in all raw modes and reset
 		 * them properly.
diff --git a/include/linux/console_struct.h b/include/linux/console_struct.h
index 57e83f1..3364898 100644
--- a/include/linux/console_struct.h
+++ b/include/linux/console_struct.h
@@ -58,7 +58,6 @@ struct vc_data {
 	/* VT terminal data */
 	unsigned int	vc_state;		/* Escape sequence parser state */
 	unsigned int	vc_npar,vc_par[NPAR];	/* Parameters of current escape sequence */
-	struct tty_struct *vc_tty;		/* TTY we are attached to */
 	/* data for manual vt switching */
 	struct vt_mode	vt_mode;
 	struct pid 	*vt_pid;
-- 
1.7.0.4

[PATCH 17/31] serial: Change the wait for carrier locking

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

We want to push the lock/unlock into the helper functions so that we
can prepare to move to using the tty_port helper. The expansion initially
comes out a bit ugly but its worth the temporary expansion IMHO just so
we can produce a nice testable series of changes.

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/serial/serial_core.c |   44 +++++++++++++++++++++++++++++++++--------
 1 files changed, 35 insertions(+), 9 deletions(-)

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 570dca2..424b1c7 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1272,6 +1272,7 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
 	struct uart_state *state = tty->driver_data;
 	struct tty_port *port;
 	struct uart_port *uport;
+	unsigned long flags;
 
 	BUG_ON(!kernel_locked());
 
@@ -1284,9 +1285,12 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
 	pr_debug("uart_close(%d) called\n", uport->line);
 
 	mutex_lock(&port->mutex);
+	spin_lock_irqsave(&port->lock, flags);
 
-	if (tty_hung_up_p(filp))
+	if (tty_hung_up_p(filp)) {
+		spin_unlock_irqrestore(&port->lock, flags);
 		goto done;
+	}
 
 	if ((tty->count == 1) && (port->count != 1)) {
 		/*
@@ -1305,8 +1309,10 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
 		       tty->name, port->count);
 		port->count = 0;
 	}
-	if (port->count)
+	if (port->count) {
+		spin_unlock_irqrestore(&port->lock, flags);
 		goto done;
+	}
 
 	/*
 	 * Now we wait for the transmit buffer to clear; and we notify
@@ -1314,6 +1320,7 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
 	 * setting tty->closing.
 	 */
 	tty->closing = 1;
+	spin_unlock_irqrestore(&port->lock, flags);
 
 	if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
 		tty_wait_until_sent(tty, msecs_to_jiffies(port->closing_wait));
@@ -1340,20 +1347,26 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
 
 	tty_ldisc_flush(tty);
 
-	tty->closing = 0;
 	tty_port_tty_set(port, NULL);
+	spin_lock_irqsave(&port->lock, flags);
+	tty->closing = 0;
 
 	if (port->blocked_open) {
+		spin_unlock_irqrestore(&port->lock, flags);
 		if (port->close_delay)
 			msleep_interruptible(port->close_delay);
+		spin_lock_irqsave(&port->lock, flags);
 	} else if (!uart_console(uport)) {
+		spin_unlock_irqrestore(&port->lock, flags);
 		uart_change_pm(state, 3);
+		spin_lock_irqsave(&port->lock, flags);
 	}
 
 	/*
 	 * Wake up anyone trying to open this port.
 	 */
 	clear_bit(ASYNCB_NORMAL_ACTIVE, &port->flags);
+	spin_unlock_irqrestore(&port->lock, flags);
 	wake_up_interruptible(&port->open_wait);
 
 done:
@@ -1429,6 +1442,7 @@ static void uart_hangup(struct tty_struct *tty)
 {
 	struct uart_state *state = tty->driver_data;
 	struct tty_port *port = &state->port;
+	unsigned long flags;
 
 	BUG_ON(!kernel_locked());
 	pr_debug("uart_hangup(%d)\n", state->uart_port->line);
@@ -1437,8 +1451,10 @@ static void uart_hangup(struct tty_struct *tty)
 	if (port->flags & ASYNC_NORMAL_ACTIVE) {
 		uart_flush_buffer(tty);
 		uart_shutdown(tty, state);
+		spin_lock_irqsave(&port->lock, flags);
 		port->count = 0;
 		clear_bit(ASYNCB_NORMAL_ACTIVE, &port->flags);
+		spin_unlock_irqrestore(&port->lock, flags);
 		tty_port_tty_set(port, NULL);
 		wake_up_interruptible(&port->open_wait);
 		wake_up_interruptible(&port->delta_msr_wait);
@@ -1496,9 +1512,13 @@ uart_block_til_ready(struct file *filp, struct uart_state *state)
 	struct uart_port *uport = state->uart_port;
 	struct tty_port *port = &state->port;
 	unsigned int mctrl;
+	unsigned long flags;
 
+	spin_lock_irqsave(&port->lock, flags);
+	if (!tty_hung_up_p(filp))
+		port->count--;
 	port->blocked_open++;
-	port->count--;
+	spin_unlock_irqrestore(&port->lock, flags);
 
 	add_wait_queue(&port->open_wait, &wait);
 	while (1) {
@@ -1535,23 +1555,26 @@ uart_block_til_ready(struct file *filp, struct uart_state *state)
 		 * not set RTS here - we want to make sure we catch
 		 * the data from the modem.
 		 */
-		if (port->tty->termios->c_cflag & CBAUD)
+		if (port->tty->termios->c_cflag & CBAUD) {
+			mutex_lock(&port->mutex);
 			uart_set_mctrl(uport, TIOCM_DTR);
+			mutex_unlock(&port->mutex);
+		}
 
 		/*
 		 * and wait for the carrier to indicate that the
 		 * modem is ready for us.
 		 */
+		mutex_lock(&port->mutex);
 		spin_lock_irq(&uport->lock);
 		uport->ops->enable_ms(uport);
 		mctrl = uport->ops->get_mctrl(uport);
 		spin_unlock_irq(&uport->lock);
+		mutex_unlock(&port->mutex);
 		if (mctrl & TIOCM_CAR)
 			break;
 
-		mutex_unlock(&port->mutex);
 		schedule();
-		mutex_lock(&port->mutex);
 
 		if (signal_pending(current))
 			break;
@@ -1559,8 +1582,11 @@ uart_block_til_ready(struct file *filp, struct uart_state *state)
 	set_current_state(TASK_RUNNING);
 	remove_wait_queue(&port->open_wait, &wait);
 
-	port->count++;
+	spin_lock_irqsave(&port->lock, flags);
+	if (!tty_hung_up_p(filp))
+		port->count++;
 	port->blocked_open--;
+	spin_unlock_irqrestore(&port->lock, flags);
 
 	if (signal_pending(current))
 		return -ERESTARTSYS;
@@ -1677,9 +1703,9 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
 	/*
 	 * If we succeeded, wait until the port is ready.
 	 */
+	mutex_unlock(&port->mutex);
 	if (retval == 0)
 		retval = uart_block_til_ready(filp, state);
-	mutex_unlock(&port->mutex);
 
 	/*
 	 * If this is the first open to succeed, adjust things to suit.
-- 
1.7.0.4

[PATCH 18/31] serial: add port helpers

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

We can make this the same as the ones that will be needed by the tty_port
helper logic that we want to move to but still call them from the existing
code base.

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/serial/serial_core.c |   51 ++++++++++++++++++++++++++++++-----------
 1 files changed, 37 insertions(+), 14 deletions(-)

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 424b1c7..2379045 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1501,6 +1501,34 @@ static void uart_update_termios(struct tty_struct *tty,
 	}
 }
 
+static int uart_carrier_raised(struct tty_port *port)
+{
+	struct uart_state *state = container_of(port, struct uart_state, port);
+	struct uart_port *uport = state->uart_port;
+	int mctrl;
+	mutex_lock(&port->mutex);
+	spin_lock_irq(&uport->lock);
+	uport->ops->enable_ms(uport);
+	mctrl = uport->ops->get_mctrl(uport);
+	spin_unlock_irq(&uport->lock);
+	mutex_unlock(&port->mutex);
+	if (mctrl & TIOCM_CAR)
+		return 1;
+	return 0;
+}
+
+static void uart_dtr_rts(struct tty_port *port, int onoff)
+{
+	struct uart_state *state = container_of(port, struct uart_state, port);
+	struct uart_port *uport = state->uart_port;
+	mutex_lock(&port->mutex);
+	if (onoff)
+		uart_set_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
+	else
+		uart_clear_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
+	mutex_unlock(&port->mutex);
+}
+
 /*
  * Block the open until the port is ready.  We must be called with
  * the per-port semaphore held.
@@ -1509,9 +1537,7 @@ static int
 uart_block_til_ready(struct file *filp, struct uart_state *state)
 {
 	DECLARE_WAITQUEUE(wait, current);
-	struct uart_port *uport = state->uart_port;
 	struct tty_port *port = &state->port;
-	unsigned int mctrl;
 	unsigned long flags;
 
 	spin_lock_irqsave(&port->lock, flags);
@@ -1555,23 +1581,14 @@ uart_block_til_ready(struct file *filp, struct uart_state *state)
 		 * not set RTS here - we want to make sure we catch
 		 * the data from the modem.
 		 */
-		if (port->tty->termios->c_cflag & CBAUD) {
-			mutex_lock(&port->mutex);
-			uart_set_mctrl(uport, TIOCM_DTR);
-			mutex_unlock(&port->mutex);
-		}
+		if (port->tty->termios->c_cflag & CBAUD)
+			tty_port_raise_dtr_rts(port);
 
 		/*
 		 * and wait for the carrier to indicate that the
 		 * modem is ready for us.
 		 */
-		mutex_lock(&port->mutex);
-		spin_lock_irq(&uport->lock);
-		uport->ops->enable_ms(uport);
-		mctrl = uport->ops->get_mctrl(uport);
-		spin_unlock_irq(&uport->lock);
-		mutex_unlock(&port->mutex);
-		if (mctrl & TIOCM_CAR)
+		if (tty_port_carrier_raised(port))
 			break;
 
 		schedule();
@@ -2349,6 +2366,11 @@ static const struct tty_operations uart_ops = {
 #endif
 };
 
+static const struct tty_port_operations uart_port_ops = {
+	.carrier_raised = uart_carrier_raised,
+	.dtr_rts	= uart_dtr_rts,
+};
+
 /**
  *	uart_register_driver - register a driver with the uart core layer
  *	@drv: low level driver structure
@@ -2405,6 +2427,7 @@ int uart_register_driver(struct uart_driver *drv)
 		struct tty_port *port = &state->port;
 
 		tty_port_init(port);
+		port->ops = &uart_port_ops;
 		port->close_delay     = 500;	/* .5 seconds */
 		port->closing_wait    = 30000;	/* 30 seconds */
 		tasklet_init(&state->tlet, uart_tasklet_action,
-- 
1.7.0.4

[PATCH 19/31] serial: trim locking on the helpers

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

The port mutex protects port->tty, but these paths never need to walk from
port->tty. They do need the low level lock as the API expects that but they
already also take it.

Thus we can drop the extra mutex lock calls here.

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/serial/serial_core.c |    5 +----
 1 files changed, 1 insertions(+), 4 deletions(-)

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 2379045..0603e0d 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1506,12 +1506,10 @@ static int uart_carrier_raised(struct tty_port *port)
 	struct uart_state *state = container_of(port, struct uart_state, port);
 	struct uart_port *uport = state->uart_port;
 	int mctrl;
-	mutex_lock(&port->mutex);
 	spin_lock_irq(&uport->lock);
 	uport->ops->enable_ms(uport);
 	mctrl = uport->ops->get_mctrl(uport);
 	spin_unlock_irq(&uport->lock);
-	mutex_unlock(&port->mutex);
 	if (mctrl & TIOCM_CAR)
 		return 1;
 	return 0;
@@ -1521,12 +1519,11 @@ static void uart_dtr_rts(struct tty_port *port, int onoff)
 {
 	struct uart_state *state = container_of(port, struct uart_state, port);
 	struct uart_port *uport = state->uart_port;
-	mutex_lock(&port->mutex);
+
 	if (onoff)
 		uart_set_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
 	else
 		uart_clear_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
-	mutex_unlock(&port->mutex);
 }
 
 /*
-- 
1.7.0.4

[PATCH 20/31] serial: Use block_til_ready helper

[Arnd Bergmann]

From: Alan Cox <alan@linux.intel.com>

Our code now rather closely resembles the helper, so switch to it.

Signed-off-by: Alan Cox <alan@linux.intel.com>
---
 drivers/serial/serial_core.c |   87 +-----------------------------------------
 1 files changed, 1 insertions(+), 86 deletions(-)

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 0603e0d..a55751a 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1526,91 +1526,6 @@ static void uart_dtr_rts(struct tty_port *port, int onoff)
 		uart_clear_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
 }
 
-/*
- * Block the open until the port is ready.  We must be called with
- * the per-port semaphore held.
- */
-static int
-uart_block_til_ready(struct file *filp, struct uart_state *state)
-{
-	DECLARE_WAITQUEUE(wait, current);
-	struct tty_port *port = &state->port;
-	unsigned long flags;
-
-	spin_lock_irqsave(&port->lock, flags);
-	if (!tty_hung_up_p(filp))
-		port->count--;
-	port->blocked_open++;
-	spin_unlock_irqrestore(&port->lock, flags);
-
-	add_wait_queue(&port->open_wait, &wait);
-	while (1) {
-		set_current_state(TASK_INTERRUPTIBLE);
-
-		/*
-		 * If we have been hung up, tell userspace/restart open.
-		 */
-		if (tty_hung_up_p(filp) || port->tty == NULL)
-			break;
-
-		/*
-		 * If the port has been closed, tell userspace/restart open.
-		 */
-		if (!(port->flags & ASYNC_INITIALIZED))
-			break;
-
-		/*
-		 * If non-blocking mode is set, or CLOCAL mode is set,
-		 * we don't want to wait for the modem status lines to
-		 * indicate that the port is ready.
-		 *
-		 * Also, if the port is not enabled/configured, we want
-		 * to allow the open to succeed here.  Note that we will
-		 * have set TTY_IO_ERROR for a non-existant port.
-		 */
-		if ((filp->f_flags & O_NONBLOCK) ||
-		    (port->tty->termios->c_cflag & CLOCAL) ||
-		    (port->tty->flags & (1 << TTY_IO_ERROR)))
-			break;
-
-		/*
-		 * Set DTR to allow modem to know we're waiting.  Do
-		 * not set RTS here - we want to make sure we catch
-		 * the data from the modem.
-		 */
-		if (port->tty->termios->c_cflag & CBAUD)
-			tty_port_raise_dtr_rts(port);
-
-		/*
-		 * and wait for the carrier to indicate that the
-		 * modem is ready for us.
-		 */
-		if (tty_port_carrier_raised(port))
-			break;
-
-		schedule();
-
-		if (signal_pending(current))
-			break;
-	}
-	set_current_state(TASK_RUNNING);
-	remove_wait_queue(&port->open_wait, &wait);
-
-	spin_lock_irqsave(&port->lock, flags);
-	if (!tty_hung_up_p(filp))
-		port->count++;
-	port->blocked_open--;
-	spin_unlock_irqrestore(&port->lock, flags);
-
-	if (signal_pending(current))
-		return -ERESTARTSYS;
-
-	if (!port->tty || tty_hung_up_p(filp))
-		return -EAGAIN;
-
-	return 0;
-}
-
 static struct uart_state *uart_get(struct uart_driver *drv, int line)
 {
 	struct uart_state *state;
@@ -1719,7 +1634,7 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
 	 */
 	mutex_unlock(&port->mutex);
 	if (retval == 0)
-		retval = uart_block_til_ready(filp, state);
+		retval = tty_port_block_til_ready(port, tty, filp);
 
 	/*
 	 * If this is the first open to succeed, adjust things to suit.
-- 
1.7.0.4

[PATCH 21/31] tty: replace BKL with a new tty_lock

[Arnd Bergmann]

As a preparation for replacing the big kernel lock
in the TTY layer, wrap all the callers in new
macros tty_lock, tty_lock_nested and tty_unlock.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/char/amiserial.c       |   16 +++---
 drivers/char/briq_panel.c      |    6 +-
 drivers/char/n_hdlc.c          |   16 +++---
 drivers/char/n_r3964.c         |    8 ++--
 drivers/char/pty.c             |    4 +-
 drivers/char/selection.c       |    4 +-
 drivers/char/serial167.c       |    4 +-
 drivers/char/sx.c              |   12 ++--
 drivers/char/tty_io.c          |  115 ++++++++++++++++++++++------------------
 drivers/char/tty_ldisc.c       |   24 +++++----
 drivers/char/vc_screen.c       |    4 +-
 drivers/char/vt_ioctl.c        |   10 ++--
 drivers/serial/68360serial.c   |    4 +-
 drivers/serial/crisv10.c       |    4 +-
 drivers/serial/serial_core.c   |   10 ++--
 drivers/video/console/vgacon.c |    4 +-
 include/linux/tty.h            |   31 +++++++++++
 17 files changed, 161 insertions(+), 115 deletions(-)

diff --git a/drivers/char/amiserial.c b/drivers/char/amiserial.c
index 4f8d60c..1b21a7a 100644
--- a/drivers/char/amiserial.c
+++ b/drivers/char/amiserial.c
@@ -1072,7 +1072,7 @@ static int get_serial_info(struct async_struct * info,
 	if (!retinfo)
 		return -EFAULT;
 	memset(&tmp, 0, sizeof(tmp));
-	lock_kernel();
+	tty_lock();
 	tmp.type = state->type;
 	tmp.line = state->line;
 	tmp.port = state->port;
@@ -1083,7 +1083,7 @@ static int get_serial_info(struct async_struct * info,
 	tmp.close_delay = state->close_delay;
 	tmp.closing_wait = state->closing_wait;
 	tmp.custom_divisor = state->custom_divisor;
-	unlock_kernel();
+	tty_unlock();
 	if (copy_to_user(retinfo,&tmp,sizeof(*retinfo)))
 		return -EFAULT;
 	return 0;
@@ -1100,14 +1100,14 @@ static int set_serial_info(struct async_struct * info,
 	if (copy_from_user(&new_serial,new_info,sizeof(new_serial)))
 		return -EFAULT;
 
-	lock_kernel();
+	tty_lock();
 	state = info->state;
 	old_state = *state;
   
 	change_irq = new_serial.irq != state->irq;
 	change_port = (new_serial.port != state->port);
 	if(change_irq || change_port || (new_serial.xmit_fifo_size != state->xmit_fifo_size)) {
-	  unlock_kernel();
+	  tty_unlock();
 	  return -EINVAL;
 	}
   
@@ -1127,7 +1127,7 @@ static int set_serial_info(struct async_struct * info,
 	}
 
 	if (new_serial.baud_base < 9600) {
-		unlock_kernel();
+		tty_unlock();
 		return -EINVAL;
 	}
 
@@ -1163,7 +1163,7 @@ check_and_exit:
 		}
 	} else
 		retval = startup(info);
-	unlock_kernel();
+	tty_unlock();
 	return retval;
 }
 
@@ -1538,7 +1538,7 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
 
 	orig_jiffies = jiffies;
 
-	lock_kernel();
+	tty_lock_nested(); /* tty_wait_until_sent is called from lots of places */
 	/*
 	 * Set the check interval to be 1/5 of the estimated time to
 	 * send a single character, and make it at least 1.  The check
@@ -1579,7 +1579,7 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
 			break;
 	}
 	__set_current_state(TASK_RUNNING);
-	unlock_kernel();
+	tty_unlock();
 #ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
 	printk("lsr = %d (jiff=%lu)...done\n", lsr, jiffies);
 #endif
diff --git a/drivers/char/briq_panel.c b/drivers/char/briq_panel.c
index 555cd93..d5fa113 100644
--- a/drivers/char/briq_panel.c
+++ b/drivers/char/briq_panel.c
@@ -67,15 +67,15 @@ static void set_led(char state)
 
 static int briq_panel_open(struct inode *ino, struct file *filep)
 {
-	lock_kernel();
+	tty_lock();
 	/* enforce single access, vfd_is_open is protected by BKL */
 	if (vfd_is_open) {
-		unlock_kernel();
+		tty_unlock();
 		return -EBUSY;
 	}
 	vfd_is_open = 1;
 
-	unlock_kernel();
+	tty_unlock();
 	return 0;
 }
 
diff --git a/drivers/char/n_hdlc.c b/drivers/char/n_hdlc.c
index c68118e..47d3228 100644
--- a/drivers/char/n_hdlc.c
+++ b/drivers/char/n_hdlc.c
@@ -598,18 +598,18 @@ static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file,
 		return -EFAULT;
 	}
 
-	lock_kernel();
+	tty_lock();
 
 	for (;;) {
 		if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
-			unlock_kernel();
+			tty_unlock();
 			return -EIO;
 		}
 
 		n_hdlc = tty2n_hdlc (tty);
 		if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC ||
 			 tty != n_hdlc->tty) {
-			unlock_kernel();
+			tty_unlock();
 			return 0;
 		}
 
@@ -619,13 +619,13 @@ static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file,
 			
 		/* no data */
 		if (file->f_flags & O_NONBLOCK) {
-			unlock_kernel();
+			tty_unlock();
 			return -EAGAIN;
 		}
 			
 		interruptible_sleep_on (&tty->read_wait);
 		if (signal_pending(current)) {
-			unlock_kernel();
+			tty_unlock();
 			return -EINTR;
 		}
 	}
@@ -648,7 +648,7 @@ static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file,
 		kfree(rbuf);
 	else	
 		n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,rbuf);
-	unlock_kernel();
+	tty_unlock();
 	return ret;
 	
 }	/* end of n_hdlc_tty_read() */
@@ -691,7 +691,7 @@ static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file,
 		count = maxframe;
 	}
 	
-	lock_kernel();
+	tty_lock();
 
 	add_wait_queue(&tty->write_wait, &wait);
 	set_current_state(TASK_INTERRUPTIBLE);
@@ -731,7 +731,7 @@ static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file,
 		n_hdlc_buf_put(&n_hdlc->tx_buf_list,tbuf);
 		n_hdlc_send_frames(n_hdlc,tty);
 	}
-	unlock_kernel();
+	tty_unlock();
 	return error;
 	
 }	/* end of n_hdlc_tty_write() */
diff --git a/drivers/char/n_r3964.c b/drivers/char/n_r3964.c
index c1d8b54..f4bd259 100644
--- a/drivers/char/n_r3964.c
+++ b/drivers/char/n_r3964.c
@@ -1067,7 +1067,7 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
 
 	TRACE_L("read()");
 
-	lock_kernel();
+	tty_lock();
 
 	pClient = findClient(pInfo, task_pid(current));
 	if (pClient) {
@@ -1109,7 +1109,7 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
 	}
 	ret = -EPERM;
 unlock:
-	unlock_kernel();
+	tty_unlock();
 	return ret;
 }
 
@@ -1158,7 +1158,7 @@ static ssize_t r3964_write(struct tty_struct *tty, struct file *file,
 	pHeader->locks = 0;
 	pHeader->owner = NULL;
 
-	lock_kernel();
+	tty_lock();
 
 	pClient = findClient(pInfo, task_pid(current));
 	if (pClient) {
@@ -1177,7 +1177,7 @@ static ssize_t r3964_write(struct tty_struct *tty, struct file *file,
 	add_tx_queue(pInfo, pHeader);
 	trigger_transmit(pInfo);
 
-	unlock_kernel();
+	tty_unlock();
 
 	return 0;
 }
diff --git a/drivers/char/pty.c b/drivers/char/pty.c
index d83a431..384e79f 100644
--- a/drivers/char/pty.c
+++ b/drivers/char/pty.c
@@ -671,9 +671,9 @@ static int ptmx_open(struct inode *inode, struct file *filp)
 {
 	int ret;
 
-	lock_kernel();
+	tty_lock();
 	ret = __ptmx_open(inode, filp);
-	unlock_kernel();
+	tty_unlock();
 	return ret;
 }
 
diff --git a/drivers/char/selection.c b/drivers/char/selection.c
index 6e79340..85211a3 100644
--- a/drivers/char/selection.c
+++ b/drivers/char/selection.c
@@ -313,7 +313,7 @@ int paste_selection(struct tty_struct *tty)
 	struct  tty_ldisc *ld;
 	DECLARE_WAITQUEUE(wait, current);
 
-	lock_kernel();
+	tty_lock_nested(); /* always called with BTM from vt_ioctl */
 
 	acquire_console_sem();
 	poke_blanked_console();
@@ -338,6 +338,6 @@ int paste_selection(struct tty_struct *tty)
 	__set_current_state(TASK_RUNNING);
 
 	tty_ldisc_deref(ld);
-	unlock_kernel();
+	tty_unlock();
 	return 0;
 }
diff --git a/drivers/char/serial167.c b/drivers/char/serial167.c
index ecbe479..90b3ec0 100644
--- a/drivers/char/serial167.c
+++ b/drivers/char/serial167.c
@@ -1505,7 +1505,7 @@ cy_ioctl(struct tty_struct *tty, struct file *file,
 	printk("cy_ioctl %s, cmd = %x arg = %lx\n", tty->name, cmd, arg);	/* */
 #endif
 
-	lock_kernel();
+	tty_lock();
 
 	switch (cmd) {
 	case CYGETMON:
@@ -1561,7 +1561,7 @@ cy_ioctl(struct tty_struct *tty, struct file *file,
 	default:
 		ret_val = -ENOIOCTLCMD;
 	}
-	unlock_kernel();
+	tty_unlock();
 
 #ifdef SERIAL_DEBUG_OTHER
 	printk("cy_ioctl done\n");
diff --git a/drivers/char/sx.c b/drivers/char/sx.c
index a81ec4f..5b24db4 100644
--- a/drivers/char/sx.c
+++ b/drivers/char/sx.c
@@ -1699,7 +1699,7 @@ static long sx_fw_ioctl(struct file *filp, unsigned int cmd,
 	if (!capable(CAP_SYS_RAWIO))
 		return -EPERM;
 
-	lock_kernel();
+	tty_lock();
 
 	sx_dprintk(SX_DEBUG_FIRMWARE, "IOCTL %x: %lx\n", cmd, arg);
 
@@ -1848,7 +1848,7 @@ static long sx_fw_ioctl(struct file *filp, unsigned int cmd,
 		break;
 	}
 out:
-	unlock_kernel();
+	tty_unlock();
 	func_exit();
 	return rc;
 }
@@ -1859,7 +1859,7 @@ static int sx_break(struct tty_struct *tty, int flag)
 	int rv;
 
 	func_enter();
-	lock_kernel();
+	tty_lock();
 
 	if (flag)
 		rv = sx_send_command(port, HS_START, -1, HS_IDLE_BREAK);
@@ -1868,7 +1868,7 @@ static int sx_break(struct tty_struct *tty, int flag)
 	if (rv != 1)
 		printk(KERN_ERR "sx: couldn't send break (%x).\n",
 			read_sx_byte(port->board, CHAN_OFFSET(port, hi_hstat)));
-	unlock_kernel();
+	tty_unlock();
 	func_exit();
 	return 0;
 }
@@ -1909,7 +1909,7 @@ static int sx_ioctl(struct tty_struct *tty, struct file *filp,
 	/* func_enter2(); */
 
 	rc = 0;
-	lock_kernel();
+	tty_lock();
 	switch (cmd) {
 	case TIOCGSERIAL:
 		rc = gs_getserial(&port->gs, argp);
@@ -1921,7 +1921,7 @@ static int sx_ioctl(struct tty_struct *tty, struct file *filp,
 		rc = -ENOIOCTLCMD;
 		break;
 	}
-	unlock_kernel();
+	tty_unlock();
 
 	/* func_exit(); */
 	return rc;
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index d71f0fc..4c2cc6b 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -149,6 +149,7 @@ static long tty_compat_ioctl(struct file *file, unsigned int cmd,
 #else
 #define tty_compat_ioctl NULL
 #endif
+static int __tty_fasync(int fd, struct file *filp, int on);
 static int tty_fasync(int fd, struct file *filp, int on);
 static void release_tty(struct tty_struct *tty, int idx);
 static void __proc_set_tty(struct task_struct *tsk, struct tty_struct *tty);
@@ -483,7 +484,7 @@ EXPORT_SYMBOL_GPL(tty_wakeup);
  *	remains intact.
  *
  *	Locking:
- *		BKL
+ *		BTM
  *		  redirect lock for undoing redirection
  *		  file list lock for manipulating list of ttys
  *		  tty_ldisc_lock from called functions
@@ -513,8 +514,11 @@ static void do_tty_hangup(struct work_struct *work)
 	}
 	spin_unlock(&redirect_lock);
 
-	/* inuse_filps is protected by the single kernel lock */
-	lock_kernel();
+	/* inuse_filps is protected by the single tty lock,
+	   this really needs to change if we want to flush the
+	   workqueue with the lock held */
+	tty_lock_nested(); /* called with BTM held from pty_close and
+				others */
 	check_tty_count(tty, "do_tty_hangup");
 
 	file_list_lock();
@@ -525,7 +529,7 @@ static void do_tty_hangup(struct work_struct *work)
 		if (filp->f_op->write != tty_write)
 			continue;
 		closecount++;
-		tty_fasync(-1, filp, 0);	/* can't block */
+		__tty_fasync(-1, filp, 0);	/* can't block */
 		filp->f_op = &hung_up_tty_fops;
 	}
 	file_list_unlock();
@@ -594,7 +598,7 @@ static void do_tty_hangup(struct work_struct *work)
 	 */
 	set_bit(TTY_HUPPED, &tty->flags);
 	tty_ldisc_enable(tty);
-	unlock_kernel();
+	tty_unlock();
 	if (f)
 		fput(f);
 }
@@ -696,7 +700,8 @@ static void session_clear_tty(struct pid *session)
  *	exiting; it is 0 if called by the ioctl TIOCNOTTY.
  *
  *	Locking:
- *		BKL is taken for hysterical raisins
+ *		BTM is taken for hysterical raisins, and held when
+ *		  called from no_tty().
  *		  tty_mutex is taken to protect tty
  *		  ->siglock is taken to protect ->signal/->sighand
  *		  tasklist_lock is taken to walk process list for sessions
@@ -714,10 +719,10 @@ void disassociate_ctty(int on_exit)
 	tty = get_current_tty();
 	if (tty) {
 		tty_pgrp = get_pid(tty->pgrp);
-		lock_kernel();
+		tty_lock_nested(); /* see above */
 		if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
 			tty_vhangup(tty);
-		unlock_kernel();
+		tty_unlock();
 		tty_kref_put(tty);
 	} else if (on_exit) {
 		struct pid *old_pgrp;
@@ -774,9 +779,9 @@ void disassociate_ctty(int on_exit)
 void no_tty(void)
 {
 	struct task_struct *tsk = current;
-	lock_kernel();
+	tty_lock();
 	disassociate_ctty(0);
-	unlock_kernel();
+	tty_unlock();
 	proc_clear_tty(tsk);
 }
 
@@ -1013,19 +1018,19 @@ out:
  * We don't put it into the syslog queue right now maybe in the future if
  * really needed.
  *
- * We must still hold the BKL and test the CLOSING flag for the moment.
+ * We must still hold the BTM and test the CLOSING flag for the moment.
  */
 
 void tty_write_message(struct tty_struct *tty, char *msg)
 {
 	if (tty) {
 		mutex_lock(&tty->atomic_write_lock);
-		lock_kernel();
+		tty_lock();
 		if (tty->ops->write && !test_bit(TTY_CLOSING, &tty->flags)) {
-			unlock_kernel();
+			tty_unlock();
 			tty->ops->write(tty, msg, strlen(msg));
 		} else
-			unlock_kernel();
+			tty_unlock();
 		tty_write_unlock(tty);
 	}
 	return;
@@ -1208,18 +1213,18 @@ static int tty_driver_install_tty(struct tty_driver *driver,
 	int ret;
 
 	if (driver->ops->install) {
-		lock_kernel();
+		tty_lock_nested(); /* already called with BTM held */
 		ret = driver->ops->install(driver, tty);
-		unlock_kernel();
+		tty_unlock();
 		return ret;
 	}
 
 	if (tty_init_termios(tty) == 0) {
-		lock_kernel();
+		tty_lock_nested();
 		tty_driver_kref_get(driver);
 		tty->count++;
 		driver->ttys[idx] = tty;
-		unlock_kernel();
+		tty_unlock();
 		return 0;
 	}
 	return -ENOMEM;
@@ -1312,14 +1317,15 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
 	struct tty_struct *tty;
 	int retval;
 
-	lock_kernel();
+	tty_lock_nested(); /* always called with tty lock held already */
+
 	/* Check if pty master is being opened multiple times */
 	if (driver->subtype == PTY_TYPE_MASTER &&
 		(driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {
-		unlock_kernel();
+		tty_unlock();
 		return ERR_PTR(-EIO);
 	}
-	unlock_kernel();
+	tty_unlock();
 
 	/*
 	 * First time open is complex, especially for PTY devices.
@@ -1363,9 +1369,9 @@ release_mem_out:
 	if (printk_ratelimit())
 		printk(KERN_INFO "tty_init_dev: ldisc open failed, "
 				 "clearing slot %d\n", idx);
-	lock_kernel();
+	tty_lock_nested();
 	release_tty(tty, idx);
-	unlock_kernel();
+	tty_unlock();
 	return ERR_PTR(retval);
 }
 
@@ -1512,10 +1518,10 @@ int tty_release(struct inode *inode, struct file *filp)
 	if (tty_paranoia_check(tty, inode, "tty_release_dev"))
 		return 0;
 
-	lock_kernel();
+	tty_lock();
 	check_tty_count(tty, "tty_release_dev");
 
-	tty_fasync(-1, filp, 0);
+	__tty_fasync(-1, filp, 0);
 
 	idx = tty->index;
 	pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
@@ -1527,18 +1533,18 @@ int tty_release(struct inode *inode, struct file *filp)
 	if (idx < 0 || idx >= tty->driver->num) {
 		printk(KERN_DEBUG "tty_release_dev: bad idx when trying to "
 				  "free (%s)\n", tty->name);
-		unlock_kernel();
+		tty_unlock();
 		return 0;
 	}
 	if (!devpts) {
 		if (tty != tty->driver->ttys[idx]) {
-			unlock_kernel();
+			tty_unlock();
 			printk(KERN_DEBUG "tty_release_dev: driver.table[%d] not tty "
 			       "for (%s)\n", idx, tty->name);
 			return 0;
 		}
 		if (tty->termios != tty->driver->termios[idx]) {
-			unlock_kernel();
+			tty_unlock();
 			printk(KERN_DEBUG "tty_release_dev: driver.termios[%d] not termios "
 			       "for (%s)\n",
 			       idx, tty->name);
@@ -1556,21 +1562,21 @@ int tty_release(struct inode *inode, struct file *filp)
 	if (tty->driver->other &&
 	     !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
 		if (o_tty != tty->driver->other->ttys[idx]) {
-			unlock_kernel();
+			tty_unlock();
 			printk(KERN_DEBUG "tty_release_dev: other->table[%d] "
 					  "not o_tty for (%s)\n",
 			       idx, tty->name);
 			return 0 ;
 		}
 		if (o_tty->termios != tty->driver->other->termios[idx]) {
-			unlock_kernel();
+			tty_unlock();
 			printk(KERN_DEBUG "tty_release_dev: other->termios[%d] "
 					  "not o_termios for (%s)\n",
 			       idx, tty->name);
 			return 0;
 		}
 		if (o_tty->link != tty) {
-			unlock_kernel();
+			tty_unlock();
 			printk(KERN_DEBUG "tty_release_dev: bad pty pointers\n");
 			return 0;
 		}
@@ -1579,7 +1585,7 @@ int tty_release(struct inode *inode, struct file *filp)
 	if (tty->ops->close)
 		tty->ops->close(tty, filp);
 
-	unlock_kernel();
+	tty_unlock();
 	/*
 	 * Sanity check: if tty->count is going to zero, there shouldn't be
 	 * any waiters on tty->read_wait or tty->write_wait.  We test the
@@ -1602,7 +1608,7 @@ int tty_release(struct inode *inode, struct file *filp)
 		   opens on /dev/tty */
 
 		mutex_lock(&tty_mutex);
-		lock_kernel();
+		tty_lock();
 		tty_closing = tty->count <= 1;
 		o_tty_closing = o_tty &&
 			(o_tty->count <= (pty_master ? 1 : 0));
@@ -1633,7 +1639,7 @@ int tty_release(struct inode *inode, struct file *filp)
 
 		printk(KERN_WARNING "tty_release_dev: %s: read/write wait queue "
 				    "active!\n", tty_name(tty, buf));
-		unlock_kernel();
+		tty_unlock();
 		mutex_unlock(&tty_mutex);
 		schedule();
 	}
@@ -1698,7 +1704,7 @@ int tty_release(struct inode *inode, struct file *filp)
 
 	/* check whether both sides are closing ... */
 	if (!tty_closing || (o_tty && !o_tty_closing)) {
-		unlock_kernel();
+		tty_unlock();
 		return 0;
 	}
 
@@ -1718,7 +1724,7 @@ int tty_release(struct inode *inode, struct file *filp)
 	/* Make this pty number available for reallocation */
 	if (devpts)
 		devpts_kill_index(inode, idx);
-	unlock_kernel();
+	tty_unlock();
 	return 0;
 }
 
@@ -1760,12 +1766,12 @@ retry_open:
 	retval = 0;
 
 	mutex_lock(&tty_mutex);
-	lock_kernel();
+	tty_lock();
 
 	if (device == MKDEV(TTYAUX_MAJOR, 0)) {
 		tty = get_current_tty();
 		if (!tty) {
-			unlock_kernel();
+			tty_unlock();
 			mutex_unlock(&tty_mutex);
 			return -ENXIO;
 		}
@@ -1797,14 +1803,14 @@ retry_open:
 				goto got_driver;
 			}
 		}
-		unlock_kernel();
+		tty_unlock();
 		mutex_unlock(&tty_mutex);
 		return -ENODEV;
 	}
 
 	driver = get_tty_driver(device, &index);
 	if (!driver) {
-		unlock_kernel();
+		tty_unlock();
 		mutex_unlock(&tty_mutex);
 		return -ENODEV;
 	}
@@ -1814,7 +1820,7 @@ got_driver:
 		tty = tty_driver_lookup_tty(driver, inode, index);
 
 		if (IS_ERR(tty)) {
-			unlock_kernel();
+			tty_unlock();
 			mutex_unlock(&tty_mutex);
 			return PTR_ERR(tty);
 		}
@@ -1830,7 +1836,7 @@ got_driver:
 	mutex_unlock(&tty_mutex);
 	tty_driver_kref_put(driver);
 	if (IS_ERR(tty)) {
-		unlock_kernel();
+		tty_unlock();
 		return PTR_ERR(tty);
 	}
 
@@ -1862,11 +1868,11 @@ got_driver:
 #endif
 		tty_release(inode, filp);
 		if (retval != -ERESTARTSYS) {
-			unlock_kernel();
+			tty_unlock();
 			return retval;
 		}
 		if (signal_pending(current)) {
-			unlock_kernel();
+			tty_unlock();
 			return retval;
 		}
 		schedule();
@@ -1875,14 +1881,14 @@ got_driver:
 		 */
 		if (filp->f_op == &hung_up_tty_fops)
 			filp->f_op = &tty_fops;
-		unlock_kernel();
+		tty_unlock();
 		goto retry_open;
 	}
-	unlock_kernel();
+	tty_unlock();
 
 
 	mutex_lock(&tty_mutex);
-	lock_kernel();
+	tty_lock();
 	spin_lock_irq(&current->sighand->siglock);
 	if (!noctty &&
 	    current->signal->leader &&
@@ -1890,7 +1896,7 @@ got_driver:
 	    tty->session == NULL)
 		__proc_set_tty(current, tty);
 	spin_unlock_irq(&current->sighand->siglock);
-	unlock_kernel();
+	tty_unlock();
 	mutex_unlock(&tty_mutex);
 	return 0;
 }
@@ -1926,13 +1932,12 @@ static unsigned int tty_poll(struct file *filp, poll_table *wait)
 	return ret;
 }
 
-static int tty_fasync(int fd, struct file *filp, int on)
+static int __tty_fasync(int fd, struct file *filp, int on)
 {
 	struct tty_struct *tty;
 	unsigned long flags;
 	int retval = 0;
 
-	lock_kernel();
 	tty = (struct tty_struct *)filp->private_data;
 	if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
 		goto out;
@@ -1966,7 +1971,15 @@ static int tty_fasync(int fd, struct file *filp, int on)
 	}
 	retval = 0;
 out:
-	unlock_kernel();
+	return retval;
+}
+
+static int tty_fasync(int fd, struct file *filp, int on)
+{
+	int retval;
+	tty_lock();
+	retval = __tty_fasync(fd, filp, on);
+	tty_unlock();
 	return retval;
 }
 
diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index 500e740..97681ff 100644
--- a/drivers/char/tty_ldisc.c
+++ b/drivers/char/tty_ldisc.c
@@ -440,6 +440,8 @@ static void tty_set_termios_ldisc(struct tty_struct *tty, int num)
  *
  *	A helper opening method. Also a convenient debugging and check
  *	point.
+ *
+ *	Locking: always called with BTM already held.
  */
 
 static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld)
@@ -447,10 +449,10 @@ static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld)
 	WARN_ON(test_and_set_bit(TTY_LDISC_OPEN, &tty->flags));
 	if (ld->ops->open) {
 		int ret;
-                /* BKL here locks verus a hangup event */
-		lock_kernel();
+                /* BTM here locks versus a hangup event */
+		tty_lock_nested(); /* always held here already */
 		ret = ld->ops->open(tty);
-		unlock_kernel();
+		tty_unlock();
 		return ret;
 	}
 	return 0;
@@ -553,7 +555,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 	if (IS_ERR(new_ldisc))
 		return PTR_ERR(new_ldisc);
 
-	lock_kernel();
+	tty_lock();
 	/*
 	 *	We need to look at the tty locking here for pty/tty pairs
 	 *	when both sides try to change in parallel.
@@ -567,12 +569,12 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 	 */
 
 	if (tty->ldisc->ops->num == ldisc) {
-		unlock_kernel();
+		tty_unlock();
 		tty_ldisc_put(new_ldisc);
 		return 0;
 	}
 
-	unlock_kernel();
+	tty_unlock();
 	/*
 	 *	Problem: What do we do if this blocks ?
 	 *	We could deadlock here
@@ -594,7 +596,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 		mutex_lock(&tty->ldisc_mutex);
 	}
 
-	lock_kernel();
+	tty_lock();
 
 	set_bit(TTY_LDISC_CHANGING, &tty->flags);
 
@@ -607,7 +609,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
 	o_ldisc = tty->ldisc;
 
-	unlock_kernel();
+	tty_unlock();
 	/*
 	 *	Make sure we don't change while someone holds a
 	 *	reference to the line discipline. The TTY_LDISC bit
@@ -633,14 +635,14 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 	flush_scheduled_work();
 
 	mutex_lock(&tty->ldisc_mutex);
-	lock_kernel();
+	tty_lock();
 	if (test_bit(TTY_HUPPED, &tty->flags)) {
 		/* We were raced by the hangup method. It will have stomped
 		   the ldisc data and closed the ldisc down */
 		clear_bit(TTY_LDISC_CHANGING, &tty->flags);
 		mutex_unlock(&tty->ldisc_mutex);
 		tty_ldisc_put(new_ldisc);
-		unlock_kernel();
+		tty_unlock();
 		return -EIO;
 	}
 
@@ -682,7 +684,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 	if (o_work)
 		schedule_delayed_work(&o_tty->buf.work, 1);
 	mutex_unlock(&tty->ldisc_mutex);
-	unlock_kernel();
+	tty_unlock();
 	return retval;
 }
 
diff --git a/drivers/char/vc_screen.c b/drivers/char/vc_screen.c
index c1791a6..bcce46c 100644
--- a/drivers/char/vc_screen.c
+++ b/drivers/char/vc_screen.c
@@ -463,10 +463,10 @@ vcs_open(struct inode *inode, struct file *filp)
 	unsigned int currcons = iminor(inode) & 127;
 	int ret = 0;
 	
-	lock_kernel();
+	tty_lock();
 	if(currcons && !vc_cons_allocated(currcons-1))
 		ret = -ENXIO;
-	unlock_kernel();
+	tty_unlock();
 	return ret;
 }
 
diff --git a/drivers/char/vt_ioctl.c b/drivers/char/vt_ioctl.c
index 625f77d..cc07fab 100644
--- a/drivers/char/vt_ioctl.c
+++ b/drivers/char/vt_ioctl.c
@@ -509,7 +509,7 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
 
 	console = vc->vc_num;
 
-	lock_kernel();
+	tty_lock();
 
 	if (!vc_cons_allocated(console)) { 	/* impossible? */
 		ret = -ENOIOCTLCMD;
@@ -1334,7 +1334,7 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
 		ret = -ENOIOCTLCMD;
 	}
 out:
-	unlock_kernel();
+	tty_unlock();
 	return ret;
 eperm:
 	ret = -EPERM;
@@ -1501,7 +1501,7 @@ long vt_compat_ioctl(struct tty_struct *tty, struct file * file,
 
 	console = vc->vc_num;
 
-	lock_kernel();
+	tty_lock();
 
 	if (!vc_cons_allocated(console)) { 	/* impossible? */
 		ret = -ENOIOCTLCMD;
@@ -1569,11 +1569,11 @@ long vt_compat_ioctl(struct tty_struct *tty, struct file * file,
 		goto fallback;
 	}
 out:
-	unlock_kernel();
+	tty_unlock();
 	return ret;
 
 fallback:
-	unlock_kernel();
+	tty_unlock();
 	return vt_ioctl(tty, file, cmd, arg);
 }
 
diff --git a/drivers/serial/68360serial.c b/drivers/serial/68360serial.c
index 24661cd..c17a595 100644
--- a/drivers/serial/68360serial.c
+++ b/drivers/serial/68360serial.c
@@ -1705,7 +1705,7 @@ static void rs_360_wait_until_sent(struct tty_struct *tty, int timeout)
 	printk("jiff=%lu...", jiffies);
 #endif
 
-	lock_kernel();
+	tty_lock_nested(); /* always held already since we come from ->close */
 	/* We go through the loop at least once because we can't tell
 	 * exactly when the last character exits the shifter.  There can
 	 * be at least two characters waiting to be sent after the buffers
@@ -1734,7 +1734,7 @@ static void rs_360_wait_until_sent(struct tty_struct *tty, int timeout)
 			bdp--;
 	} while (bdp->status & BD_SC_READY);
 	current->state = TASK_RUNNING;
-	unlock_kernel();
+	tty_unlock();
 #ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
 	printk("lsr = %d (jiff=%lu)...done\n", lsr, jiffies);
 #endif
diff --git a/drivers/serial/crisv10.c b/drivers/serial/crisv10.c
index 31f1723..d11d898 100644
--- a/drivers/serial/crisv10.c
+++ b/drivers/serial/crisv10.c
@@ -3924,7 +3924,7 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
 	 * Check R_DMA_CHx_STATUS bit 0-6=number of available bytes in FIFO
 	 * R_DMA_CHx_HWSW bit 31-16=nbr of bytes left in DMA buffer (0=64k)
 	 */
-	lock_kernel();
+	tty_lock_nested(); /* locked already when coming from close */
 	orig_jiffies = jiffies;
 	while (info->xmit.head != info->xmit.tail || /* More in send queue */
 	       (*info->ostatusadr & 0x007f) ||  /* more in FIFO */
@@ -3941,7 +3941,7 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
 			curr_time_usec - info->last_tx_active_usec;
 	}
 	set_current_state(TASK_RUNNING);
-	unlock_kernel();
+	tty_unlock();
 }
 
 /*
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index a55751a..4b151a4 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1274,7 +1274,7 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
 	struct uart_port *uport;
 	unsigned long flags;
 
-	BUG_ON(!kernel_locked());
+	BUG_ON(!tty_locked());
 
 	if (!state)
 		return;
@@ -1382,7 +1382,7 @@ static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
 	if (port->type == PORT_UNKNOWN || port->fifosize == 0)
 		return;
 
-	lock_kernel();
+	tty_lock_nested(); /* already locked when coming from close */
 
 	/*
 	 * Set the check interval to be 1/5 of the estimated time to
@@ -1429,7 +1429,7 @@ static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
 			break;
 	}
 	set_current_state(TASK_RUNNING); /* might not be needed */
-	unlock_kernel();
+	tty_unlock();
 }
 
 /*
@@ -1444,7 +1444,7 @@ static void uart_hangup(struct tty_struct *tty)
 	struct tty_port *port = &state->port;
 	unsigned long flags;
 
-	BUG_ON(!kernel_locked());
+	BUG_ON(!tty_locked());
 	pr_debug("uart_hangup(%d)\n", state->uart_port->line);
 
 	mutex_lock(&port->mutex);
@@ -1570,7 +1570,7 @@ static int uart_open(struct tty_struct *tty, struct file *filp)
 	struct tty_port *port;
 	int retval, line = tty->index;
 
-	BUG_ON(!kernel_locked());
+	BUG_ON(!tty_locked());
 	pr_debug("uart_open(%d) called\n", line);
 
 	/*
diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index 182dd6f..7197005 100644
--- a/drivers/video/console/vgacon.c
+++ b/drivers/video/console/vgacon.c
@@ -1108,7 +1108,7 @@ static int vgacon_do_font_op(struct vgastate *state,char *arg,int set,int ch512)
 		charmap += 4 * cmapsz;
 #endif
 
-	unlock_kernel();
+	tty_unlock();
 	spin_lock_irq(&vga_lock);
 	/* First, the Sequencer */
 	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x1);
@@ -1192,7 +1192,7 @@ static int vgacon_do_font_op(struct vgastate *state,char *arg,int set,int ch512)
 		vga_wattr(state->vgabase, VGA_AR_ENABLE_DISPLAY, 0);	
 	}
 	spin_unlock_irq(&vga_lock);
-	lock_kernel();
+	tty_lock();
 	return 0;
 }
 
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 931078b..faf0bcd 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -13,6 +13,7 @@
 #include <linux/tty_driver.h>
 #include <linux/tty_ldisc.h>
 #include <linux/mutex.h>
+#include <linux/smp_lock.h>
 
 #include <asm/system.h>
 
@@ -572,5 +573,35 @@ extern int vt_ioctl(struct tty_struct *tty, struct file *file,
 extern long vt_compat_ioctl(struct tty_struct *tty, struct file * file,
 		     unsigned int cmd, unsigned long arg);
 
+/* functions for preparation of BKL removal */
+
+/*
+ * tty_lock_nested get the tty_lock while potentially holding it
+ *
+ * The Big TTY Mutex is a recursive lock, meaning you can take it
+ * from a thread that is already holding it.
+ * This is bad for a number of reasons, so tty_lock_nested should
+ * really be used as rarely as possible. If a code location can
+ * be shown to never get called with this held already, it should
+ * use tty_lock() instead.
+ */
+static inline void __lockfunc tty_lock_nested(void) __acquires(kernel_lock)
+{
+	lock_kernel();
+}
+static inline void tty_lock(void) __acquires(kernel_lock)
+{
+#ifdef CONFIG_LOCK_KERNEL
+	/* kernel_locked is 1 for !CONFIG_LOCK_KERNEL */
+	WARN_ON(kernel_locked());
+#endif
+	lock_kernel();
+}
+static inline void tty_unlock(void) __releases(kernel_lock)
+{
+	unlock_kernel();
+}
+#define tty_locked()		(kernel_locked())
+
 #endif /* __KERNEL__ */
 #endif
-- 
1.7.0.4

[PATCH 22/31] tty: never hold BTM while getting tty_mutex

[Arnd Bergmann]

tty_mutex is never taken with the BTM held, except for
two corner cases that are worked around here.
We give up the BTM before calling tty_release() in the
error path of tty_open().
Similarly, we reorder the locking in ptmx_open()
to get tty_mutex before the BTM.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/char/pty.c    |   24 +++++++++++-------------
 drivers/char/tty_io.c |   12 ++++++------
 2 files changed, 17 insertions(+), 19 deletions(-)

diff --git a/drivers/char/pty.c b/drivers/char/pty.c
index 384e79f..d9c1407 100644
--- a/drivers/char/pty.c
+++ b/drivers/char/pty.c
@@ -626,7 +626,7 @@ static const struct tty_operations pty_unix98_ops = {
  *		allocated_ptys_lock handles the list of free pty numbers
  */
 
-static int __ptmx_open(struct inode *inode, struct file *filp)
+static int ptmx_open(struct inode *inode, struct file *filp)
 {
 	struct tty_struct *tty;
 	int retval;
@@ -635,11 +635,14 @@ static int __ptmx_open(struct inode *inode, struct file *filp)
 	nonseekable_open(inode, filp);
 
 	/* find a device that is not in use. */
+	tty_lock();
 	index = devpts_new_index(inode);
+	tty_unlock();
 	if (index < 0)
 		return index;
 
 	mutex_lock(&tty_mutex);
+	tty_lock();
 	tty = tty_init_dev(ptm_driver, index, 1);
 	mutex_unlock(&tty_mutex);
 
@@ -657,24 +660,19 @@ static int __ptmx_open(struct inode *inode, struct file *filp)
 		goto out1;
 
 	retval = ptm_driver->ops->open(tty, filp);
-	if (!retval)
-		return 0;
+	if (retval)
+		goto out2;
 out1:
+	tty_unlock();
+	return retval;
+out2:
+	tty_unlock();
 	tty_release(inode, filp);
 	return retval;
 out:
 	devpts_kill_index(inode, index);
-	return retval;
-}
-
-static int ptmx_open(struct inode *inode, struct file *filp)
-{
-	int ret;
-
-	tty_lock();
-	ret = __ptmx_open(inode, filp);
 	tty_unlock();
-	return ret;
+	return retval;
 }
 
 static struct file_operations ptmx_fops;
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 4c2cc6b..d51993b 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1866,19 +1866,19 @@ got_driver:
 		printk(KERN_DEBUG "error %d in opening %s...", retval,
 		       tty->name);
 #endif
+		tty_unlock(); /* need to call tty_release without BTM */
 		tty_release(inode, filp);
-		if (retval != -ERESTARTSYS) {
-			tty_unlock();
+		if (retval != -ERESTARTSYS)
 			return retval;
-		}
-		if (signal_pending(current)) {
-			tty_unlock();
+
+		if (signal_pending(current))
 			return retval;
-		}
+
 		schedule();
 		/*
 		 * Need to reset f_op in case a hangup happened.
 		 */
+		tty_lock();
 		if (filp->f_op == &hung_up_tty_fops)
 			filp->f_op = &tty_fops;
 		tty_unlock();
-- 
1.7.0.4

[PATCH 23/31] tty: fix console_sem lock order

[Arnd Bergmann]

vgacon_do_font_op releases and reacquires the BTM while holding
console_sem. This violates the rule that BTM has to be the
outer lock whenever we hold both.

There does not seem to be any reason to give up the BTM here,
so just stop doing that.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/video/console/vgacon.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c
index 7197005..54e32c5 100644
--- a/drivers/video/console/vgacon.c
+++ b/drivers/video/console/vgacon.c
@@ -1108,7 +1108,6 @@ static int vgacon_do_font_op(struct vgastate *state,char *arg,int set,int ch512)
 		charmap += 4 * cmapsz;
 #endif
 
-	tty_unlock();
 	spin_lock_irq(&vga_lock);
 	/* First, the Sequencer */
 	vga_wseq(state->vgabase, VGA_SEQ_RESET, 0x1);
@@ -1192,7 +1191,6 @@ static int vgacon_do_font_op(struct vgastate *state,char *arg,int set,int ch512)
 		vga_wattr(state->vgabase, VGA_AR_ENABLE_DISPLAY, 0);	
 	}
 	spin_unlock_irq(&vga_lock);
-	tty_lock();
 	return 0;
 }
 
-- 
1.7.0.4

[PATCH 24/31] cdc-acm: remove dead code

[Arnd Bergmann]

The wait_event_interruptible_timeout in acm_port_down is
never reached. Remove it to avoid possible deadlocks
with the big tty mutex if someone were to start using
the blocking version of acm_port_down.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/usb/class/cdc-acm.c |   12 +++---------
 1 files changed, 3 insertions(+), 9 deletions(-)

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 0c2f14f..d00d155 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -636,19 +636,13 @@ static void acm_tty_unregister(struct acm *acm)
 
 static int acm_tty_chars_in_buffer(struct tty_struct *tty);
 
-static void acm_port_down(struct acm *acm, int drain)
+static void acm_port_down(struct acm *acm)
 {
 	int i, nr = acm->rx_buflimit;
 	mutex_lock(&open_mutex);
 	if (acm->dev) {
 		usb_autopm_get_interface(acm->control);
 		acm_set_control(acm, acm->ctrlout = 0);
-		/* try letting the last writes drain naturally */
-		if (drain) {
-			wait_event_interruptible_timeout(acm->drain_wait,
-				(ACM_NW == acm_wb_is_avail(acm)) || !acm->dev,
-					ACM_CLOSE_TIMEOUT * HZ);
-		}
 		usb_kill_urb(acm->ctrlurb);
 		for (i = 0; i < ACM_NW; i++)
 			usb_kill_urb(acm->wb[i].urb);
@@ -664,7 +658,7 @@ static void acm_tty_hangup(struct tty_struct *tty)
 {
 	struct acm *acm = tty->driver_data;
 	tty_port_hangup(&acm->port);
-	acm_port_down(acm, 0);
+	acm_port_down(acm);
 }
 
 static void acm_tty_close(struct tty_struct *tty, struct file *filp)
@@ -685,7 +679,7 @@ static void acm_tty_close(struct tty_struct *tty, struct file *filp)
 		mutex_unlock(&open_mutex);
 		return;
 	}
-	acm_port_down(acm, 0);
+	acm_port_down(acm);
 	tty_port_close_end(&acm->port, tty);
 	tty_port_tty_set(&acm->port, NULL);
 }
-- 
1.7.0.4

[PATCH 25/31] tty: introduce wait_event_interruptible_tty

[Arnd Bergmann]

Calling wait_event_interruptible implicitly
releases the BKL when it sleeps, but we need
to do this explcitly when we have converted
it to a mutex.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/char/cyclades.c  |    2 +-
 drivers/char/istallion.c |   12 ++++++++----
 drivers/char/n_r3964.c   |    2 +-
 drivers/char/tty_port.c  |    2 +-
 drivers/char/vt_ioctl.c  |    2 +-
 drivers/serial/crisv10.c |    4 ++--
 include/linux/tty.h      |   42 ++++++++++++++++++++++++++++++++++++++++++
 7 files changed, 56 insertions(+), 10 deletions(-)

diff --git a/drivers/char/cyclades.c b/drivers/char/cyclades.c
index 51acfe3..27aad94 100644
--- a/drivers/char/cyclades.c
+++ b/drivers/char/cyclades.c
@@ -1607,7 +1607,7 @@ static int cy_open(struct tty_struct *tty, struct file *filp)
 	 * If the port is the middle of closing, bail out now
 	 */
 	if (tty_hung_up_p(filp) || (info->port.flags & ASYNC_CLOSING)) {
-		wait_event_interruptible(info->port.close_wait,
+		wait_event_interruptible_tty(info->port.close_wait,
 				!(info->port.flags & ASYNC_CLOSING));
 		return (info->port.flags & ASYNC_HUP_NOTIFY) ? -EAGAIN: -ERESTARTSYS;
 	}
diff --git a/drivers/char/istallion.c b/drivers/char/istallion.c
index 5e9a81d..be28391 100644
--- a/drivers/char/istallion.c
+++ b/drivers/char/istallion.c
@@ -954,7 +954,7 @@ static int stli_rawopen(struct stlibrd *brdp, struct stliport *portp, unsigned l
  *	order of opens and closes may not be preserved across shared
  *	memory, so we must wait until it is complete.
  */
-	wait_event_interruptible(portp->raw_wait,
+	wait_event_interruptible_tty(portp->raw_wait,
 			!test_bit(ST_CLOSING, &portp->state));
 	if (signal_pending(current)) {
 		return -ERESTARTSYS;
@@ -989,7 +989,7 @@ static int stli_rawopen(struct stlibrd *brdp, struct stliport *portp, unsigned l
 	set_bit(ST_OPENING, &portp->state);
 	spin_unlock_irqrestore(&brd_lock, flags);
 
-	wait_event_interruptible(portp->raw_wait,
+	wait_event_interruptible_tty(portp->raw_wait,
 			!test_bit(ST_OPENING, &portp->state));
 	if (signal_pending(current))
 		rc = -ERESTARTSYS;
@@ -1020,7 +1020,7 @@ static int stli_rawclose(struct stlibrd *brdp, struct stliport *portp, unsigned
  *	occurs on this port.
  */
 	if (wait) {
-		wait_event_interruptible(portp->raw_wait,
+		wait_event_interruptible_tty(portp->raw_wait,
 				!test_bit(ST_CLOSING, &portp->state));
 		if (signal_pending(current)) {
 			return -ERESTARTSYS;
@@ -1052,7 +1052,7 @@ static int stli_rawclose(struct stlibrd *brdp, struct stliport *portp, unsigned
  *	to come back.
  */
 	rc = 0;
-	wait_event_interruptible(portp->raw_wait,
+	wait_event_interruptible_tty(portp->raw_wait,
 			!test_bit(ST_CLOSING, &portp->state));
 	if (signal_pending(current))
 		rc = -ERESTARTSYS;
@@ -1073,6 +1073,10 @@ static int stli_rawclose(struct stlibrd *brdp, struct stliport *portp, unsigned
 
 static int stli_cmdwait(struct stlibrd *brdp, struct stliport *portp, unsigned long cmd, void *arg, int size, int copyback)
 {
+	/*
+	 * no need for wait_event_tty because clearing ST_CMDING cannot block
+	 * on BTM
+	 */
 	wait_event_interruptible(portp->raw_wait,
 			!test_bit(ST_CMDING, &portp->state));
 	if (signal_pending(current))
diff --git a/drivers/char/n_r3964.c b/drivers/char/n_r3964.c
index f4bd259..a98290d 100644
--- a/drivers/char/n_r3964.c
+++ b/drivers/char/n_r3964.c
@@ -1079,7 +1079,7 @@ static ssize_t r3964_read(struct tty_struct *tty, struct file *file,
 				goto unlock;
 			}
 			/* block until there is a message: */
-			wait_event_interruptible(pInfo->read_wait,
+			wait_event_interruptible_tty(pInfo->read_wait,
 					(pMsg = remove_msg(pInfo, pClient)));
 		}
 
diff --git a/drivers/char/tty_port.c b/drivers/char/tty_port.c
index a3bd1d0..35eb304 100644
--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -231,7 +231,7 @@ int tty_port_block_til_ready(struct tty_port *port,
 
 	/* block if port is in the process of being closed */
 	if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) {
-		wait_event_interruptible(port->close_wait,
+		wait_event_interruptible_tty(port->close_wait,
 				!(port->flags & ASYNC_CLOSING));
 		if (port->flags & ASYNC_HUP_NOTIFY)
 			return -EAGAIN;
diff --git a/drivers/char/vt_ioctl.c b/drivers/char/vt_ioctl.c
index cc07fab..c56c4f3 100644
--- a/drivers/char/vt_ioctl.c
+++ b/drivers/char/vt_ioctl.c
@@ -133,7 +133,7 @@ static void vt_event_wait(struct vt_event_wait *vw)
 	list_add(&vw->list, &vt_events);
 	spin_unlock_irqrestore(&vt_event_lock, flags);
 	/* Wait for it to pass */
-	wait_event_interruptible(vt_event_waitqueue, vw->done);
+	wait_event_interruptible_tty(vt_event_waitqueue, vw->done);
 	/* Dequeue it */
 	spin_lock_irqsave(&vt_event_lock, flags);
 	list_del(&vw->list);
diff --git a/drivers/serial/crisv10.c b/drivers/serial/crisv10.c
index d11d898..e6a1cb7 100644
--- a/drivers/serial/crisv10.c
+++ b/drivers/serial/crisv10.c
@@ -3981,7 +3981,7 @@ block_til_ready(struct tty_struct *tty, struct file * filp,
 	 */
 	if (tty_hung_up_p(filp) ||
 	    (info->flags & ASYNC_CLOSING)) {
-		wait_event_interruptible(info->close_wait,
+		wait_event_interruptible_tty(info->close_wait,
 			!(info->flags & ASYNC_CLOSING));
 #ifdef SERIAL_DO_RESTART
 		if (info->flags & ASYNC_HUP_NOTIFY)
@@ -4139,7 +4139,7 @@ rs_open(struct tty_struct *tty, struct file * filp)
 	 */
 	if (tty_hung_up_p(filp) ||
 	    (info->flags & ASYNC_CLOSING)) {
-		wait_event_interruptible(info->close_wait,
+		wait_event_interruptible_tty(info->close_wait,
 			!(info->flags & ASYNC_CLOSING));
 #ifdef SERIAL_DO_RESTART
 		return ((info->flags & ASYNC_HUP_NOTIFY) ?
diff --git a/include/linux/tty.h b/include/linux/tty.h
index faf0bcd..18a7955 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -603,5 +603,47 @@ static inline void tty_unlock(void) __releases(kernel_lock)
 }
 #define tty_locked()		(kernel_locked())
 
+/*
+ * wait_event_interruptible_tty -- wait for a condition with the tty lock held
+ *
+ * The condition we are waiting for might take a long time to
+ * become true, or might depend on another thread taking the
+ * BTM. In either case, we need to drop the BTM to guarantee
+ * forward progress. This is a leftover from the conversion
+ * from the BKL and should eventually get removed as the BTM
+ * falls out of use.
+ *
+ * Do not use in new code.
+ */
+#define wait_event_interruptible_tty(wq, condition)			\
+({									\
+	int __ret = 0;							\
+	if (!(condition)) {						\
+		__wait_event_interruptible_tty(wq, condition, __ret);	\
+	}								\
+	__ret;								\
+})
+
+#define __wait_event_interruptible_tty(wq, condition, ret)		\
+do {									\
+	DEFINE_WAIT(__wait);						\
+									\
+	for (;;) {							\
+		prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE);	\
+		if (condition)						\
+			break;						\
+		if (!signal_pending(current)) {				\
+			tty_unlock();					\
+			schedule();					\
+			tty_lock();					\
+			continue;					\
+		}							\
+		ret = -ERESTARTSYS;					\
+		break;							\
+	}								\
+	finish_wait(&wq, &__wait);					\
+} while (0)
+
+
 #endif /* __KERNEL__ */
 #endif
-- 
1.7.0.4

[PATCH 26/31] tty: reorder ldisc locking

[Arnd Bergmann]

We need to release the BTM in paste_selection() when
sleeping in tty_ldisc_ref_wait to avoid deadlocks
with tty_ldisc_enable.

In tty_set_ldisc, we now always grab the BTM before
taking the ldisc_mutex in order to avoid AB-BA
deadlocks between the two.

tty_ldisc_halt potentially blocks on a workqueue
function that takes the BTM, so we must release
the BTM before calling it.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/char/selection.c |    9 +++++++--
 drivers/char/tty_ldisc.c |   24 ++++++++++++++++++++----
 2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/drivers/char/selection.c b/drivers/char/selection.c
index 85211a3..75889cd 100644
--- a/drivers/char/selection.c
+++ b/drivers/char/selection.c
@@ -319,8 +319,13 @@ int paste_selection(struct tty_struct *tty)
 	poke_blanked_console();
 	release_console_sem();
 
-	ld = tty_ldisc_ref_wait(tty);
-	
+	ld = tty_ldisc_ref(tty);
+	if (!ld) {
+		tty_unlock();
+		ld = tty_ldisc_ref_wait(tty);
+		tty_lock();
+	}
+
 	add_wait_queue(&vc->paste_wait, &wait);
 	while (sel_buffer && sel_buffer_lth > pasted) {
 		set_current_state(TASK_INTERRUPTIBLE);
diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index 97681ff..0f49479 100644
--- a/drivers/char/tty_ldisc.c
+++ b/drivers/char/tty_ldisc.c
@@ -582,6 +582,7 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
 	tty_wait_until_sent(tty, 0);
 
+	tty_lock();
 	mutex_lock(&tty->ldisc_mutex);
 
 	/*
@@ -591,13 +592,13 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
 	while (test_bit(TTY_LDISC_CHANGING, &tty->flags)) {
 		mutex_unlock(&tty->ldisc_mutex);
+		tty_unlock();
 		wait_event(tty_ldisc_wait,
 			test_bit(TTY_LDISC_CHANGING, &tty->flags) == 0);
+		tty_lock();
 		mutex_lock(&tty->ldisc_mutex);
 	}
 
-	tty_lock();
-
 	set_bit(TTY_LDISC_CHANGING, &tty->flags);
 
 	/*
@@ -634,8 +635,8 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc)
 
 	flush_scheduled_work();
 
-	mutex_lock(&tty->ldisc_mutex);
 	tty_lock();
+	mutex_lock(&tty->ldisc_mutex);
 	if (test_bit(TTY_HUPPED, &tty->flags)) {
 		/* We were raced by the hangup method. It will have stomped
 		   the ldisc data and closed the ldisc down */
@@ -782,7 +783,20 @@ void tty_ldisc_hangup(struct tty_struct *tty)
 	 * Avoid racing set_ldisc or tty_ldisc_release
 	 */
 	mutex_lock(&tty->ldisc_mutex);
-	tty_ldisc_halt(tty);
+
+	/*
+	 * this is like tty_ldisc_halt, but we need to give up
+	 * the BTM before calling cancel_delayed_work_sync,
+	 * which may need to wait for another function taking the BTM
+	 */
+	clear_bit(TTY_LDISC, &tty->flags);
+	tty_unlock();
+	cancel_delayed_work_sync(&tty->buf.work);
+	mutex_unlock(&tty->ldisc_mutex);
+
+	tty_lock();
+	mutex_lock(&tty->ldisc_mutex);
+
 	/* At this point we have a closed ldisc and we want to
 	   reopen it. We could defer this to the next open but
 	   it means auditing a lot of other paths so this is
@@ -853,8 +867,10 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
 	 * race with the set_ldisc code path.
 	 */
 
+	tty_unlock();
 	tty_ldisc_halt(tty);
 	flush_scheduled_work();
+	tty_lock();
 
 	mutex_lock(&tty->ldisc_mutex);
 	/*
-- 
1.7.0.4

[PATCH 27/31] tty: untangle locking of wait_until_sent

[Arnd Bergmann]

Some wait_until_sent versions require the big
tty mutex, others don't and some callers of
wait_until_sent already hold it while other don't.
That leads to recursive use of the BTM in these
functions, which we're trying to get rid of.

This turns all cleans up the locking there so
that the driver's wait_until_sent function
never takes the BTM itself if it is already
called with that lock held.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/char/amiserial.c     |   11 +++++++++--
 drivers/serial/68360serial.c |    2 --
 drivers/serial/crisv10.c     |    2 --
 drivers/serial/serial_core.c |   31 ++++++++++++++++++++++---------
 4 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/drivers/char/amiserial.c b/drivers/char/amiserial.c
index 1b21a7a..8228e61 100644
--- a/drivers/char/amiserial.c
+++ b/drivers/char/amiserial.c
@@ -1528,6 +1528,7 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
 {
 	struct async_struct * info = tty->driver_data;
 	unsigned long orig_jiffies, char_time;
+	int tty_was_locked = tty_locked();
 	int lsr;
 
 	if (serial_paranoia_check(info, tty->name, "rs_wait_until_sent"))
@@ -1538,7 +1539,12 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
 
 	orig_jiffies = jiffies;
 
-	tty_lock_nested(); /* tty_wait_until_sent is called from lots of places */
+	/*
+	 * tty_wait_until_sent is called from lots of places,
+	 * with or without the BTM.
+	 */
+	if (!tty_was_locked)
+		tty_lock();
 	/*
 	 * Set the check interval to be 1/5 of the estimated time to
 	 * send a single character, and make it at least 1.  The check
@@ -1579,7 +1585,8 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
 			break;
 	}
 	__set_current_state(TASK_RUNNING);
-	tty_unlock();
+	if (!tty_was_locked)
+		tty_unlock();
 #ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
 	printk("lsr = %d (jiff=%lu)...done\n", lsr, jiffies);
 #endif
diff --git a/drivers/serial/68360serial.c b/drivers/serial/68360serial.c
index c17a595..5b7b801 100644
--- a/drivers/serial/68360serial.c
+++ b/drivers/serial/68360serial.c
@@ -1705,7 +1705,6 @@ static void rs_360_wait_until_sent(struct tty_struct *tty, int timeout)
 	printk("jiff=%lu...", jiffies);
 #endif
 
-	tty_lock_nested(); /* always held already since we come from ->close */
 	/* We go through the loop at least once because we can't tell
 	 * exactly when the last character exits the shifter.  There can
 	 * be at least two characters waiting to be sent after the buffers
@@ -1734,7 +1733,6 @@ static void rs_360_wait_until_sent(struct tty_struct *tty, int timeout)
 			bdp--;
 	} while (bdp->status & BD_SC_READY);
 	current->state = TASK_RUNNING;
-	tty_unlock();
 #ifdef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT
 	printk("lsr = %d (jiff=%lu)...done\n", lsr, jiffies);
 #endif
diff --git a/drivers/serial/crisv10.c b/drivers/serial/crisv10.c
index e6a1cb7..0825d4a 100644
--- a/drivers/serial/crisv10.c
+++ b/drivers/serial/crisv10.c
@@ -3924,7 +3924,6 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
 	 * Check R_DMA_CHx_STATUS bit 0-6=number of available bytes in FIFO
 	 * R_DMA_CHx_HWSW bit 31-16=nbr of bytes left in DMA buffer (0=64k)
 	 */
-	tty_lock_nested(); /* locked already when coming from close */
 	orig_jiffies = jiffies;
 	while (info->xmit.head != info->xmit.tail || /* More in send queue */
 	       (*info->ostatusadr & 0x007f) ||  /* more in FIFO */
@@ -3941,7 +3940,6 @@ static void rs_wait_until_sent(struct tty_struct *tty, int timeout)
 			curr_time_usec - info->last_tx_active_usec;
 	}
 	set_current_state(TASK_RUNNING);
-	tty_unlock();
 }
 
 /*
diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 4b151a4..78b1eac 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -60,7 +60,7 @@ static struct lock_class_key port_lock_key;
 
 static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
 					struct ktermios *old_termios);
-static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
+static void __uart_wait_until_sent(struct uart_port *port, int timeout);
 static void uart_change_pm(struct uart_state *state, int pm_state);
 
 /*
@@ -1322,8 +1322,16 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
 	tty->closing = 1;
 	spin_unlock_irqrestore(&port->lock, flags);
 
-	if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
-		tty_wait_until_sent(tty, msecs_to_jiffies(port->closing_wait));
+	if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE) {
+		/*
+		 * hack: open-coded tty_wait_until_sent to avoid
+		 * recursive tty_lock
+		 */
+		long timeout = msecs_to_jiffies(port->closing_wait);
+		if (wait_event_interruptible_timeout(tty->write_wait,
+				!tty_chars_in_buffer(tty), timeout) >= 0)
+			__uart_wait_until_sent(uport, timeout);
+	}
 
 	/*
 	 * At this point, we stop accepting input.  To do this, we
@@ -1339,7 +1347,7 @@ static void uart_close(struct tty_struct *tty, struct file *filp)
 		 * has completely drained; this is especially
 		 * important if there is a transmit FIFO!
 		 */
-		uart_wait_until_sent(tty, uport->timeout);
+		__uart_wait_until_sent(uport, uport->timeout);
 	}
 
 	uart_shutdown(tty, state);
@@ -1373,17 +1381,13 @@ done:
 	mutex_unlock(&port->mutex);
 }
 
-static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
+static void __uart_wait_until_sent(struct uart_port *port, int timeout)
 {
-	struct uart_state *state = tty->driver_data;
-	struct uart_port *port = state->uart_port;
 	unsigned long char_time, expire;
 
 	if (port->type == PORT_UNKNOWN || port->fifosize == 0)
 		return;
 
-	tty_lock_nested(); /* already locked when coming from close */
-
 	/*
 	 * Set the check interval to be 1/5 of the estimated time to
 	 * send a single character, and make it at least 1.  The check
@@ -1429,6 +1433,15 @@ static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
 			break;
 	}
 	set_current_state(TASK_RUNNING); /* might not be needed */
+}
+
+static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
+{
+	struct uart_state *state = tty->driver_data;
+	struct uart_port *port = state->uart_port;
+
+	tty_lock();
+	__uart_wait_until_sent(port, timeout);
 	tty_unlock();
 }
 
-- 
1.7.0.4

[PATCH 28/31] tty: remove tty_lock_nested

[Arnd Bergmann]

This changes all remaining users of tty_lock_nested
to be non-recursive, which lets us kill this function.
As a consequence, we won't need to keep the lock count
any more, which allows more simplifications later.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/char/pty.c       |    2 +-
 drivers/char/selection.c |    4 ++--
 drivers/char/tty_io.c    |   41 ++++++++++++++++++++---------------------
 drivers/char/tty_ldisc.c |    3 +--
 include/linux/tty.h      |   16 +---------------
 5 files changed, 25 insertions(+), 41 deletions(-)

diff --git a/drivers/char/pty.c b/drivers/char/pty.c
index d9c1407..c9af9ff 100644
--- a/drivers/char/pty.c
+++ b/drivers/char/pty.c
@@ -62,7 +62,7 @@ static void pty_close(struct tty_struct *tty, struct file *filp)
 		if (tty->driver == ptm_driver)
 			devpts_pty_kill(tty->link);
 #endif
-		tty_vhangup(tty->link);
+		tty_vhangup_locked(tty->link);
 	}
 }
 
diff --git a/drivers/char/selection.c b/drivers/char/selection.c
index 75889cd..ebae344 100644
--- a/drivers/char/selection.c
+++ b/drivers/char/selection.c
@@ -313,7 +313,8 @@ int paste_selection(struct tty_struct *tty)
 	struct  tty_ldisc *ld;
 	DECLARE_WAITQUEUE(wait, current);
 
-	tty_lock_nested(); /* always called with BTM from vt_ioctl */
+	/* always called with BTM from vt_ioctl */
+	WARN_ON(!tty_locked());
 
 	acquire_console_sem();
 	poke_blanked_console();
@@ -343,6 +344,5 @@ int paste_selection(struct tty_struct *tty)
 	__set_current_state(TASK_RUNNING);
 
 	tty_ldisc_deref(ld);
-	tty_unlock();
 	return 0;
 }
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index d51993b..5db354d 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -492,10 +492,8 @@ EXPORT_SYMBOL_GPL(tty_wakeup);
  *		  tasklist_lock to walk task list for hangup event
  *		    ->siglock to protect ->signal/->sighand
  */
-static void do_tty_hangup(struct work_struct *work)
+void tty_vhangup_locked(struct tty_struct *tty)
 {
-	struct tty_struct *tty =
-		container_of(work, struct tty_struct, hangup_work);
 	struct file *cons_filp = NULL;
 	struct file *filp, *f = NULL;
 	struct task_struct *p;
@@ -517,8 +515,6 @@ static void do_tty_hangup(struct work_struct *work)
 	/* inuse_filps is protected by the single tty lock,
 	   this really needs to change if we want to flush the
 	   workqueue with the lock held */
-	tty_lock_nested(); /* called with BTM held from pty_close and
-				others */
 	check_tty_count(tty, "do_tty_hangup");
 
 	file_list_lock();
@@ -598,11 +594,20 @@ static void do_tty_hangup(struct work_struct *work)
 	 */
 	set_bit(TTY_HUPPED, &tty->flags);
 	tty_ldisc_enable(tty);
-	tty_unlock();
 	if (f)
 		fput(f);
 }
 
+static void do_tty_hangup(struct work_struct *work)
+{
+	struct tty_struct *tty =
+		container_of(work, struct tty_struct, hangup_work);
+
+	tty_lock();
+	tty_vhangup_locked(tty);
+	tty_unlock();
+}
+
 /**
  *	tty_hangup		-	trigger a hangup event
  *	@tty: tty to hangup
@@ -638,7 +643,9 @@ void tty_vhangup(struct tty_struct *tty)
 
 	printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
 #endif
-	do_tty_hangup(&tty->hangup_work);
+	tty_lock();
+	tty_vhangup_locked(tty);
+	tty_unlock();
 }
 
 EXPORT_SYMBOL(tty_vhangup);
@@ -719,10 +726,12 @@ void disassociate_ctty(int on_exit)
 	tty = get_current_tty();
 	if (tty) {
 		tty_pgrp = get_pid(tty->pgrp);
-		tty_lock_nested(); /* see above */
-		if (on_exit && tty->driver->type != TTY_DRIVER_TYPE_PTY)
-			tty_vhangup(tty);
-		tty_unlock();
+		if (on_exit) {
+			tty_lock();
+			if (tty->driver->type != TTY_DRIVER_TYPE_PTY)
+				tty_vhangup_locked(tty);
+			tty_unlock();
+		}
 		tty_kref_put(tty);
 	} else if (on_exit) {
 		struct pid *old_pgrp;
@@ -1213,18 +1222,14 @@ static int tty_driver_install_tty(struct tty_driver *driver,
 	int ret;
 
 	if (driver->ops->install) {
-		tty_lock_nested(); /* already called with BTM held */
 		ret = driver->ops->install(driver, tty);
-		tty_unlock();
 		return ret;
 	}
 
 	if (tty_init_termios(tty) == 0) {
-		tty_lock_nested();
 		tty_driver_kref_get(driver);
 		tty->count++;
 		driver->ttys[idx] = tty;
-		tty_unlock();
 		return 0;
 	}
 	return -ENOMEM;
@@ -1317,15 +1322,11 @@ struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
 	struct tty_struct *tty;
 	int retval;
 
-	tty_lock_nested(); /* always called with tty lock held already */
-
 	/* Check if pty master is being opened multiple times */
 	if (driver->subtype == PTY_TYPE_MASTER &&
 		(driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {
-		tty_unlock();
 		return ERR_PTR(-EIO);
 	}
-	tty_unlock();
 
 	/*
 	 * First time open is complex, especially for PTY devices.
@@ -1369,9 +1370,7 @@ release_mem_out:
 	if (printk_ratelimit())
 		printk(KERN_INFO "tty_init_dev: ldisc open failed, "
 				 "clearing slot %d\n", idx);
-	tty_lock_nested();
 	release_tty(tty, idx);
-	tty_unlock();
 	return ERR_PTR(retval);
 }
 
diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index 0f49479..412f977 100644
--- a/drivers/char/tty_ldisc.c
+++ b/drivers/char/tty_ldisc.c
@@ -450,9 +450,8 @@ static int tty_ldisc_open(struct tty_struct *tty, struct tty_ldisc *ld)
 	if (ld->ops->open) {
 		int ret;
                 /* BTM here locks versus a hangup event */
-		tty_lock_nested(); /* always held here already */
+		WARN_ON(!tty_locked());
 		ret = ld->ops->open(tty);
-		tty_unlock();
 		return ret;
 	}
 	return 0;
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 18a7955..21a6de2 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -416,6 +416,7 @@ extern int is_ignored(int sig);
 extern int tty_signal(int sig, struct tty_struct *tty);
 extern void tty_hangup(struct tty_struct *tty);
 extern void tty_vhangup(struct tty_struct *tty);
+extern void tty_vhangup_locked(struct tty_struct *tty);
 extern void tty_vhangup_self(void);
 extern void tty_unhangup(struct file *filp);
 extern int tty_hung_up_p(struct file *filp);
@@ -574,21 +575,6 @@ extern long vt_compat_ioctl(struct tty_struct *tty, struct file * file,
 		     unsigned int cmd, unsigned long arg);
 
 /* functions for preparation of BKL removal */
-
-/*
- * tty_lock_nested get the tty_lock while potentially holding it
- *
- * The Big TTY Mutex is a recursive lock, meaning you can take it
- * from a thread that is already holding it.
- * This is bad for a number of reasons, so tty_lock_nested should
- * really be used as rarely as possible. If a code location can
- * be shown to never get called with this held already, it should
- * use tty_lock() instead.
- */
-static inline void __lockfunc tty_lock_nested(void) __acquires(kernel_lock)
-{
-	lock_kernel();
-}
 static inline void tty_lock(void) __acquires(kernel_lock)
 {
 #ifdef CONFIG_LOCK_KERNEL
-- 
1.7.0.4

[PATCH 29/31] tty: implement BTM as mutex instead of BKL

[Arnd Bergmann]

The tty locking now follows the rules for mutexes, so
we can replace the BKL usage with a new subsystem
wide mutex.

This patch for now makes the new behaviour an optional
experimental feature that can be enabled for testing
purposes.

Using a regular mutex here will change the behaviour
when blocked on the BTM from spinning to sleeping,
but that should not be visible to the user.

Using the mutex also means that all the BTM is now
covered by lockdep.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/char/Makefile    |    1 +
 drivers/char/tty_mutex.c |   47 ++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/tty.h      |    8 +++++++
 lib/Kconfig.debug        |   10 +++++++++
 4 files changed, 66 insertions(+), 0 deletions(-)
 create mode 100644 drivers/char/tty_mutex.c

diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index 88d6eac..658bfbe 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -9,6 +9,7 @@ FONTMAPFILE = cp437.uni
 
 obj-y	 += mem.o random.o tty_io.o n_tty.o tty_ioctl.o tty_ldisc.o tty_buffer.o tty_port.o
 
+obj-$(CONFIG_TTY_MUTEX)		+= tty_mutex.o
 obj-$(CONFIG_LEGACY_PTYS)	+= pty.o
 obj-$(CONFIG_UNIX98_PTYS)	+= pty.o
 obj-y				+= misc.o
diff --git a/drivers/char/tty_mutex.c b/drivers/char/tty_mutex.c
new file mode 100644
index 0000000..1336975
--- /dev/null
+++ b/drivers/char/tty_mutex.c
@@ -0,0 +1,47 @@
+/*
+ * drivers/char/tty_lock.c
+ */
+#include <linux/tty.h>
+#include <linux/module.h>
+#include <linux/kallsyms.h>
+#include <linux/semaphore.h>
+#include <linux/sched.h>
+
+/*
+ * The 'big tty mutex'
+ *
+ * This mutex is taken and released by tty_lock() and tty_unlock(),
+ * replacing the older big kernel lock.
+ * It can no longer be taken recursively, and does not get
+ * released implicitly while sleeping.
+ *
+ * Don't use in new code.
+ */
+static DEFINE_MUTEX(big_tty_mutex);
+struct task_struct *__big_tty_mutex_owner;
+EXPORT_SYMBOL_GPL(__big_tty_mutex_owner);
+
+/*
+ * Getting the big tty mutex.
+ */
+void __lockfunc tty_lock(void)
+{
+	struct task_struct *task = current;
+
+	WARN_ON(__big_tty_mutex_owner == task);
+
+	mutex_lock(&big_tty_mutex);
+	__big_tty_mutex_owner = task;
+}
+EXPORT_SYMBOL(tty_lock);
+
+void __lockfunc tty_unlock(void)
+{
+	struct task_struct *task = current;
+
+	WARN_ON(__big_tty_mutex_owner != task);
+	__big_tty_mutex_owner = NULL;
+
+	mutex_unlock(&big_tty_mutex);
+}
+EXPORT_SYMBOL(tty_unlock);
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 21a6de2..3e7e04a 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -574,7 +574,14 @@ extern int vt_ioctl(struct tty_struct *tty, struct file *file,
 extern long vt_compat_ioctl(struct tty_struct *tty, struct file * file,
 		     unsigned int cmd, unsigned long arg);
 
+/* tty_mutex.c */
 /* functions for preparation of BKL removal */
+#ifdef CONFIG_TTY_MUTEX
+extern void __lockfunc tty_lock(void) __acquires(tty_lock);
+extern void __lockfunc tty_unlock(void) __releases(tty_lock);
+extern struct task_struct *__big_tty_mutex_owner;
+#define tty_locked()		(current == __big_tty_mutex_owner)
+#else
 static inline void tty_lock(void) __acquires(kernel_lock)
 {
 #ifdef CONFIG_LOCK_KERNEL
@@ -588,6 +595,7 @@ static inline void tty_unlock(void) __releases(kernel_lock)
 	unlock_kernel();
 }
 #define tty_locked()		(kernel_locked())
+#endif
 
 /*
  * wait_event_interruptible_tty -- wait for a condition with the tty lock held
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index e722e9d..fd1a2f1 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -428,6 +428,16 @@ config RT_MUTEX_TESTER
 	help
 	  This option enables a rt-mutex tester.
 
+config TTY_MUTEX
+	bool "Use a mutex instead of BKL for TTY locking"
+	depends on EXPERIMENTAL && SMP
+	help
+	  The TTY subsystem traditionally depends on the big kernel lock
+	  for serialization. Saying Y here replaces the BKL with the Big
+	  TTY Mutex (BTM).
+	  Building a kernel without the BKL is only possible with TTY_MUTEX
+	  enabled.
+
 config DEBUG_SPINLOCK
 	bool "Spinlock and rw-lock debugging: basic checks"
 	depends on DEBUG_KERNEL
-- 
1.7.0.4

[PATCH 30/31] tty: release BTM while sleeping in block_til_ready

[Arnd Bergmann]

Most tty drivers may block while opening a device.
Since this possibly depends on another thread
closing it first and both threads may need the BTM,
we need to release it here.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/char/amiserial.c     |    2 ++
 drivers/char/ip2/ip2main.c   |    4 ++++
 drivers/char/serial167.c     |    4 +++-
 drivers/char/specialix.c     |    2 ++
 drivers/char/synclink.c      |    2 ++
 drivers/char/synclink_gt.c   |    2 ++
 drivers/char/synclinkmp.c    |    2 ++
 drivers/char/tty_port.c      |    2 ++
 drivers/serial/68328serial.c |    2 ++
 drivers/serial/68360serial.c |    2 ++
 drivers/serial/crisv10.c     |    2 ++
 11 files changed, 25 insertions(+), 1 deletions(-)

diff --git a/drivers/char/amiserial.c b/drivers/char/amiserial.c
index 8228e61..a11c8c9 100644
--- a/drivers/char/amiserial.c
+++ b/drivers/char/amiserial.c
@@ -1710,7 +1710,9 @@ static int block_til_ready(struct tty_struct *tty, struct file * filp,
 		printk("block_til_ready blocking: ttys%d, count = %d\n",
 		       info->line, state->count);
 #endif
+		tty_unlock();
 		schedule();
+		tty_lock();
 	}
 	__set_current_state(TASK_RUNNING);
 	remove_wait_queue(&info->open_wait, &wait);
diff --git a/drivers/char/ip2/ip2main.c b/drivers/char/ip2/ip2main.c
index 911e1da..07f3ea3 100644
--- a/drivers/char/ip2/ip2main.c
+++ b/drivers/char/ip2/ip2main.c
@@ -1486,7 +1486,9 @@ ip2_open( PTTY tty, struct file *pFile )
 
 	if ( tty_hung_up_p(pFile) || ( pCh->flags & ASYNC_CLOSING )) {
 		if ( pCh->flags & ASYNC_CLOSING ) {
+			tty_unlock();
 			schedule();
+			tty_lock();
 		}
 		if ( tty_hung_up_p(pFile) ) {
 			set_current_state( TASK_RUNNING );
@@ -1548,7 +1550,9 @@ ip2_open( PTTY tty, struct file *pFile )
 			rc = (( pCh->flags & ASYNC_HUP_NOTIFY ) ? -EAGAIN : -ERESTARTSYS);
 			break;
 		}
+		tty_unlock();
 		schedule();
+		tty_lock();
 	}
 	set_current_state( TASK_RUNNING );
 	remove_wait_queue(&pCh->open_wait, &wait);
diff --git a/drivers/char/serial167.c b/drivers/char/serial167.c
index 90b3ec0..f646725 100644
--- a/drivers/char/serial167.c
+++ b/drivers/char/serial167.c
@@ -1786,7 +1786,9 @@ block_til_ready(struct tty_struct *tty, struct file *filp,
 		       tty->name, info->count);
 		/**/
 #endif
-		    schedule();
+		tty_unlock();
+		schedule();
+		tty_lock();
 	}
 	__set_current_state(TASK_RUNNING);
 	remove_wait_queue(&info->open_wait, &wait);
diff --git a/drivers/char/specialix.c b/drivers/char/specialix.c
index 7be456f..9f8495b 100644
--- a/drivers/char/specialix.c
+++ b/drivers/char/specialix.c
@@ -1365,7 +1365,9 @@ static int block_til_ready(struct tty_struct *tty, struct file *filp,
 			retval = -ERESTARTSYS;
 			break;
 		}
+		tty_unlock();
 		schedule();
+		tty_lock();
 	}
 
 	set_current_state(TASK_RUNNING);
diff --git a/drivers/char/synclink.c b/drivers/char/synclink.c
index 4de1246..c1a004f 100644
--- a/drivers/char/synclink.c
+++ b/drivers/char/synclink.c
@@ -3349,7 +3349,9 @@ static int block_til_ready(struct tty_struct *tty, struct file * filp,
 			printk("%s(%d):block_til_ready blocking on %s count=%d\n",
 				 __FILE__,__LINE__, tty->driver->name, port->count );
 				 
+		tty_unlock();
 		schedule();
+		tty_lock();
 	}
 	
 	set_current_state(TASK_RUNNING);
diff --git a/drivers/char/synclink_gt.c b/drivers/char/synclink_gt.c
index c56b70a..99fae38 100644
--- a/drivers/char/synclink_gt.c
+++ b/drivers/char/synclink_gt.c
@@ -3244,7 +3244,9 @@ static int block_til_ready(struct tty_struct *tty, struct file *filp,
 		}
 
 		DBGINFO(("%s block_til_ready wait\n", tty->driver->name));
+		tty_unlock();
 		schedule();
+		tty_lock();
 	}
 
 	set_current_state(TASK_RUNNING);
diff --git a/drivers/char/synclinkmp.c b/drivers/char/synclinkmp.c
index cfa581e..eb58d5f 100644
--- a/drivers/char/synclinkmp.c
+++ b/drivers/char/synclinkmp.c
@@ -3365,7 +3365,9 @@ static int block_til_ready(struct tty_struct *tty, struct file *filp,
 			printk("%s(%d):%s block_til_ready() count=%d\n",
 				 __FILE__,__LINE__, tty->driver->name, port->count );
 
+		tty_unlock();
 		schedule();
+		tty_lock();
 	}
 
 	set_current_state(TASK_RUNNING);
diff --git a/drivers/char/tty_port.c b/drivers/char/tty_port.c
index 35eb304..33d37d2 100644
--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -294,7 +294,9 @@ int tty_port_block_til_ready(struct tty_port *port,
 			retval = -ERESTARTSYS;
 			break;
 		}
+		tty_unlock();
 		schedule();
+		tty_lock();
 	}
 	finish_wait(&port->open_wait, &wait);
 
diff --git a/drivers/serial/68328serial.c b/drivers/serial/68328serial.c
index 3046386..0e91896 100644
--- a/drivers/serial/68328serial.c
+++ b/drivers/serial/68328serial.c
@@ -1243,7 +1243,9 @@ static int block_til_ready(struct tty_struct *tty, struct file * filp,
 			retval = -ERESTARTSYS;
 			break;
 		}
+		tty_unlock();
 		schedule();
+		tty_lock();
 	}
 	current->state = TASK_RUNNING;
 	remove_wait_queue(&info->open_wait, &wait);
diff --git a/drivers/serial/68360serial.c b/drivers/serial/68360serial.c
index 5b7b801..8b8e4c3 100644
--- a/drivers/serial/68360serial.c
+++ b/drivers/serial/68360serial.c
@@ -1860,7 +1860,9 @@ static int block_til_ready(struct tty_struct *tty, struct file * filp,
 		printk("block_til_ready blocking: ttys%d, count = %d\n",
 		       info->line, state->count);
 #endif
+		tty_unlock();
 		schedule();
+		tty_lock();
 	}
 	current->state = TASK_RUNNING;
 	remove_wait_queue(&info->open_wait, &wait);
diff --git a/drivers/serial/crisv10.c b/drivers/serial/crisv10.c
index 0825d4a..ca47072 100644
--- a/drivers/serial/crisv10.c
+++ b/drivers/serial/crisv10.c
@@ -4055,7 +4055,9 @@ block_til_ready(struct tty_struct *tty, struct file * filp,
 		printk("block_til_ready blocking: ttyS%d, count = %d\n",
 		       info->line, info->count);
 #endif
+		tty_unlock();
 		schedule();
+		tty_lock();
 	}
 	set_current_state(TASK_RUNNING);
 	remove_wait_queue(&info->open_wait, &wait);
-- 
1.7.0.4

[PATCH 31/31] 8250: fix set_ldisc operation

[Arnd Bergmann]

The ldisc number now gets passed into ->set_ldisc.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/serial/8250.c |    9 ++-------
 1 files changed, 2 insertions(+), 7 deletions(-)

diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 891e1dd..93c8358 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -2409,14 +2409,9 @@ serial8250_set_termios(struct uart_port *port, struct ktermios *termios,
 }
 
 static void
-serial8250_set_ldisc(struct uart_port *port)
+serial8250_set_ldisc(struct uart_port *port, int new)
 {
-	int line = port->line;
-
-	if (line >= port->state->port.tty->driver->num)
-		return;
-
-	if (port->state->port.tty->ldisc->ops->num == N_PPS) {
+	if (new == N_PPS) {
 		port->flags |= UPF_HARDPPS_CD;
 		serial8250_enable_ms(port);
 	} else
-- 
1.7.0.4

Re: [PATCH 00/31] tty: BKL removal

[Arnd Bergmann]

On Tuesday 01 June 2010 22:52:40 Arnd Bergmann wrote:
> Hi Greg,
> 
> As promised, here is a resend of the patches from
> both Alan and myself, making the BKL optional
> in the TTY layer. Please apply to your tty-next
> tree.

FWIW, I've documented what I've learned about the BKL (now BTM)
locking in the tty code, see
http://kernelnewbies.org/BigKernelLock?action=AttachFile&do=view&target=tty_lock.png

I hope that helps in the process of killing the BTM itself.

	Arnd

Re: [PATCH 00/31] tty: BKL removal

[Greg KH]

On Thu, Jun 03, 2010 at 12:16:44AM +0200, Arnd Bergmann wrote:
> On Tuesday 01 June 2010 22:52:40 Arnd Bergmann wrote:
> > Hi Greg,
> > 
> > As promised, here is a resend of the patches from
> > both Alan and myself, making the BKL optional
> > in the TTY layer. Please apply to your tty-next
> > tree.
> 
> FWIW, I've documented what I've learned about the BKL (now BTM)
> locking in the tty code, see
> http://kernelnewbies.org/BigKernelLock?action=AttachFile&do=view&target=tty_lock.png
> 
> I hope that helps in the process of killing the BTM itself.

Very cool, thanks for documenting this.  I'll queue up your patches in a
few days.

greg k-h

Re: [PATCH 00/31] tty: BKL removal

[Greg KH]

On Tue, Jun 01, 2010 at 10:52:40PM +0200, Arnd Bergmann wrote:
> Hi Greg,
> 
> As promised, here is a resend of the patches from
> both Alan and myself, making the BKL optional
> in the TTY layer. Please apply to your tty-next
> tree.

All applied now, thanks for doing this work.

let's see what breaks now :)

thanks,

greg k-h