[PATCH 54/75] tty: relock epca

Alan Cox
2009-01-02T13:47:45Z

From: Alan Cox <alan@redhat.com>

Bring epca into line with the port locking.

Signed-off-by: Alan Cox <alan@redhat.com>
---

drivers/char/epca.c | 195 +++++++++++++++++++++++++++------------------------
1 files changed, 104 insertions(+), 91 deletions(-)

diff --git a/drivers/char/epca.c b/drivers/char/epca.c
index da2d2cf..e07d792 100644
--- a/drivers/char/epca.c
+++ b/drivers/char/epca.c
@@ -69,7 +69,9 @@ static int invalid_lilo_config;

/*
* The ISA boards do window flipping into the same spaces so its only sane with
- * a single lock. It's still pretty efficient.
+ * a single lock. It's still pretty efficient. This lock guards the hardware
+ * and the tty_port lock guards the kernel side stuff like use counts. Take
+ * this lock inside the port lock if you must take both.
*/
static DEFINE_SPINLOCK(epca_lock);

@@ -156,7 +158,7 @@ static struct channel *verifyChannel(struct tty_struct *);
static void pc_sched_event(struct channel *, int);
static void epca_error(int, char *);
static void pc_close(struct tty_struct *, struct file *);
-static void shutdown(struct channel *);
+static void shutdown(struct channel *, struct tty_struct *tty);
static void pc_hangup(struct tty_struct *);
static int pc_write_room(struct tty_struct *);
static int pc_chars_in_buffer(struct tty_struct *);
@@ -419,76 +421,78 @@ static void epca_error(int line, char *msg)
static void pc_close(struct tty_struct *tty, struct file *filp)
{
struct channel *ch;
+ struct tty_port *port;
unsigned long flags;
/*
* verifyChannel returns the channel from the tty struct if it is
* valid. This serves as a sanity check.
*/
ch = verifyChannel(tty);
- if (ch != NULL) {
- spin_lock_irqsave(&epca_lock, flags);
- if (tty_hung_up_p(filp)) {
- spin_unlock_irqrestore(&epca_lock, flags);
- return;
- }
- if (ch->port.count-- > 1) {
- /* Begin channel is open more than once */
- /*
- * Return without doing anything. Someone might still
- * be using the channel.
- */
- spin_unlock_irqrestore(&epca_lock, flags);
- return;
- }
- /* Port open only once go ahead with shutdown & reset */
- BUG_ON(ch->port.count < 0);
+ if (ch == NULL)
+ return;
+ port = &ch->port;

+ spin_lock_irqsave(&port->lock, flags);
+ if (tty_hung_up_p(filp)) {
+ spin_unlock_irqrestore(&port->lock, flags);
+ return;
+ }
+ if (port->count-- > 1) {
+ /* Begin channel is open more than once */
/*
- * Let the rest of the driver know the channel is being closed.
- * This becomes important if an open is attempted before close
- * is finished.
+ * Return without doing anything. Someone might still
+ * be using the channel.
*/
- ch->port.flags |= ASYNC_CLOSING;
- tty->closing = 1;
-
- spin_unlock_irqrestore(&epca_lock, flags);
-
- if (ch->port.flags & ASYNC_INITIALIZED) {
- /* Setup an event to indicate when the
- transmit buffer empties */
- setup_empty_event(tty, ch);
- /* 30 seconds timeout */
- tty_wait_until_sent(tty, 3000);
- }
- pc_flush_buffer(tty);
+ spin_unlock_irqrestore(&port->lock, flags);
+ return;
+ }
+ /* Port open only once go ahead with shutdown & reset */
+ WARN_ON(port->count < 0);

- tty_ldisc_flush(tty);
- shutdown(ch);
+ /*
+ * Let the rest of the driver know the channel is being closed.
+ * This becomes important if an open is attempted before close
+ * is finished.
+ */
+ port->flags |= ASYNC_CLOSING;
+ tty->closing = 1;

- spin_lock_irqsave(&epca_lock, flags);
- tty->closing = 0;
- ch->event = 0;
- ch->port.tty = NULL;
- spin_unlock_irqrestore(&epca_lock, flags);
+ spin_unlock_irqrestore(&port->lock, flags);

- if (ch->port.blocked_open) {
- if (ch->close_delay)
- msleep_interruptible(jiffies_to_msecs(ch->close_delay));
- wake_up_interruptible(&ch->port.open_wait);
- }
- ch->port.flags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_INITIALIZED |
- ASYNC_CLOSING);
- wake_up_interruptible(&ch->port.close_wait);
+ if (port->flags & ASYNC_INITIALIZED) {
+ /* Setup an event to indicate when the
+ transmit buffer empties */
+ setup_empty_event(tty, ch);
+ /* 30 seconds timeout */
+ tty_wait_until_sent(tty, 3000);
+ }
+ pc_flush_buffer(tty);
+ tty_ldisc_flush(tty);
+ shutdown(ch, tty);
+
+ spin_lock_irqsave(&port->lock, flags);
+ tty->closing = 0;
+ ch->event = 0;
+ port->tty = NULL;
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ if (port->blocked_open) {
+ if (ch->close_delay)
+ msleep_interruptible(jiffies_to_msecs(ch->close_delay));
+ wake_up_interruptible(&port->open_wait);
}
+ port->flags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_INITIALIZED |
+ ASYNC_CLOSING);
+ wake_up_interruptible(&port->close_wait);
}

-static void shutdown(struct channel *ch)
+static void shutdown(struct channel *ch, struct tty_struct *tty)
{
unsigned long flags;
- struct tty_struct *tty;
struct board_chan __iomem *bc;
+ struct tty_port *port = &ch->port;

- if (!(ch->port.flags & ASYNC_INITIALIZED))
+ if (!(port->flags & ASYNC_INITIALIZED))
return;

spin_lock_irqsave(&epca_lock, flags);
@@ -503,7 +507,6 @@ static void shutdown(struct channel *ch)
*/
if (bc)
writeb(0, &bc->idata);
- tty = ch->port.tty;

/* If we're a modem control device and HUPCL is on, drop RTS & DTR. */
if (tty->termios->c_cflag & HUPCL) {
@@ -517,13 +520,15 @@ static void shutdown(struct channel *ch)
* will have to reinitialized. Set a flag to indicate this.
*/
/* Prevent future Digi programmed interrupts from coming active */
- ch->port.flags &= ~ASYNC_INITIALIZED;
+ port->flags &= ~ASYNC_INITIALIZED;
spin_unlock_irqrestore(&epca_lock, flags);
}

static void pc_hangup(struct tty_struct *tty)
{
struct channel *ch;
+ struct tty_port *port;
+
/*
* verifyChannel returns the channel from the tty struct if it is
* valid. This serves as a sanity check.
@@ -531,18 +536,19 @@ static void pc_hangup(struct tty_struct *tty)
ch = verifyChannel(tty);
if (ch != NULL) {
unsigned long flags;
+ port = &ch->port;

pc_flush_buffer(tty);
tty_ldisc_flush(tty);
- shutdown(ch);
-
- spin_lock_irqsave(&epca_lock, flags);
- ch->port.tty = NULL;
- ch->event = 0;
- ch->port.count = 0;
- ch->port.flags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_INITIALIZED);
- spin_unlock_irqrestore(&epca_lock, flags);
- wake_up_interruptible(&ch->port.open_wait);
+ shutdown(ch, tty);
+
+ spin_lock_irqsave(&port->lock, flags);
+ port->tty = NULL;
+ ch->event = 0; /* FIXME: review locking of ch->event */
+ port->count = 0;
+ port->flags &= ~(ASYNC_NORMAL_ACTIVE | ASYNC_INITIALIZED);
+ spin_unlock_irqrestore(&port->lock, flags);
+ wake_up_interruptible(&port->open_wait);
}
}

@@ -792,9 +798,10 @@ static int block_til_ready(struct tty_struct *tty,
DECLARE_WAITQUEUE(wait, current);
int retval, do_clocal = 0;
unsigned long flags;
+ struct tty_port *port = &ch->port;

if (tty_hung_up_p(filp)) {
- if (ch->port.flags & ASYNC_HUP_NOTIFY)
+ if (port->flags & ASYNC_HUP_NOTIFY)
retval = -EAGAIN;
else
retval = -ERESTARTSYS;
@@ -805,10 +812,10 @@ static int block_til_ready(struct tty_struct *tty,
* If the device is in the middle of being closed, then block until
* it's done, and then try again.
*/
- if (ch->port.flags & ASYNC_CLOSING) {
- interruptible_sleep_on(&ch->port.close_wait);
+ if (port->flags & ASYNC_CLOSING) {
+ interruptible_sleep_on(&port->close_wait);

- if (ch->port.flags & ASYNC_HUP_NOTIFY)
+ if (port->flags & ASYNC_HUP_NOTIFY)
return -EAGAIN;
else
return -ERESTARTSYS;
@@ -819,7 +826,7 @@ static int block_til_ready(struct tty_struct *tty,
* If non-blocking mode is set, then make the check up front
* and then exit.
*/
- ch->port.flags |= ASYNC_NORMAL_ACTIVE;
+ port->flags |= ASYNC_NORMAL_ACTIVE;
return 0;
}
if (tty->termios->c_cflag & CLOCAL)
@@ -827,31 +834,31 @@ static int block_til_ready(struct tty_struct *tty,
/* Block waiting for the carrier detect and the line to become free */

retval = 0;
- add_wait_queue(&ch->port.open_wait, &wait);
+ add_wait_queue(&port->open_wait, &wait);

- spin_lock_irqsave(&epca_lock, flags);
+ spin_lock_irqsave(&port->lock, flags);
/* We dec count so that pc_close will know when to free things */
if (!tty_hung_up_p(filp))
- ch->port.count--;
- ch->port.blocked_open++;
+ port->count--;
+ port->blocked_open++;
while (1) {
set_current_state(TASK_INTERRUPTIBLE);
if (tty_hung_up_p(filp) ||
- !(ch->port.flags & ASYNC_INITIALIZED)) {
- if (ch->port.flags & ASYNC_HUP_NOTIFY)
+ !(port->flags & ASYNC_INITIALIZED)) {
+ if (port->flags & ASYNC_HUP_NOTIFY)
retval = -EAGAIN;
else
retval = -ERESTARTSYS;
break;
}
- if (!(ch->port.flags & ASYNC_CLOSING) &&
+ if (!(port->flags & ASYNC_CLOSING) &&
(do_clocal || (ch->imodem & ch->dcd)))
break;
if (signal_pending(current)) {
retval = -ERESTARTSYS;
break;
}
- spin_unlock_irqrestore(&epca_lock, flags);
+ spin_unlock_irqrestore(&port->lock, flags);
/*
* Allow someone else to be scheduled. We will occasionally go
* through this loop until one of the above conditions change.
@@ -859,27 +866,28 @@ static int block_til_ready(struct tty_struct *tty,
* and prevent this loop from hogging the cpu.
*/
schedule();
- spin_lock_irqsave(&epca_lock, flags);
+ spin_lock_irqsave(&port->lock, flags);
}

__set_current_state(TASK_RUNNING);
- remove_wait_queue(&ch->port.open_wait, &wait);
+ remove_wait_queue(&port->open_wait, &wait);
if (!tty_hung_up_p(filp))
- ch->port.count++;
- ch->port.blocked_open--;
+ port->count++;
+ port->blocked_open--;

- spin_unlock_irqrestore(&epca_lock, flags);
+ spin_unlock_irqrestore(&port->lock, flags);

if (retval)
return retval;

- ch->port.flags |= ASYNC_NORMAL_ACTIVE;
+ port->flags |= ASYNC_NORMAL_ACTIVE;
return 0;
}

static int pc_open(struct tty_struct *tty, struct file *filp)
{
struct channel *ch;
+ struct tty_port *port;
unsigned long flags;
int line, retval, boardnum;
struct board_chan __iomem *bc;
@@ -890,6 +898,7 @@ static int pc_open(struct tty_struct *tty, struct file *filp)
return -ENODEV;

ch = &digi_channels[line];
+ port = &ch->port;
boardnum = ch->boardnum;

/* Check status of board configured in system. */
@@ -926,22 +935,24 @@ static int pc_open(struct tty_struct *tty, struct file *filp)
return -ENODEV;
}

- spin_lock_irqsave(&epca_lock, flags);
+ spin_lock_irqsave(&port->lock, flags);
/*
* Every time a channel is opened, increment a counter. This is
* necessary because we do not wish to flush and shutdown the channel
* until the last app holding the channel open, closes it.
*/
- ch->port.count++;
+ port->count++;
/*
* Set a kernel structures pointer to our local channel structure. This
* way we can get to it when passed only a tty struct.
*/
tty->driver_data = ch;
+ port->tty = tty;
/*
* If this is the first time the channel has been opened, initialize
* the tty->termios struct otherwise let pc_close handle it.
*/
+ spin_lock(&epca_lock);
globalwinon(ch);
ch->statusflags = 0;

@@ -956,16 +967,16 @@ static int pc_open(struct tty_struct *tty, struct file *filp)
writew(head, &bc->rout);

/* Set the channels associated tty structure */
- ch->port.tty = tty;

/*
* The below routine generally sets up parity, baud, flow control
* issues, etc.... It effect both control flags and input flags.
*/
epcaparam(tty, ch);
- ch->port.flags |= ASYNC_INITIALIZED;
memoff(ch);
- spin_unlock_irqrestore(&epca_lock, flags);
+ spin_unlock(&epca_lock);
+ port->flags |= ASYNC_INITIALIZED;
+ spin_unlock_irqrestore(&port->lock, flags);

retval = block_til_ready(tty, filp, ch);
if (retval)
@@ -974,13 +985,15 @@ static int pc_open(struct tty_struct *tty, struct file *filp)
* Set this again in case a hangup set it to zero while this open() was
* waiting for the line...
*/
- spin_lock_irqsave(&epca_lock, flags);
- ch->port.tty = tty;
+ spin_lock_irqsave(&port->lock, flags);
+ port->tty = tty;
+ spin_lock(&epca_lock);
globalwinon(ch);
/* Enable Digi Data events */
writeb(1, &bc->idata);
memoff(ch);
- spin_unlock_irqrestore(&epca_lock, flags);
+ spin_unlock(&epca_lock);
+ spin_unlock_irqrestore(&port->lock, flags);
return 0;
}