[PATCH AUTOSEL 6.6 11/20] serial: imx: Introduce timeout when waiting on transmitter empty

[PATCH AUTOSEL 6.6 11/20] serial: imx: Introduce timeout when waiting on transmitter empty

[Sasha Levin]

From: Esben Haabendal <esben@geanix.com>

[ Upstream commit e533e4c62e9993e62e947ae9bbec34e4c7ae81c2 ]

By waiting at most 1 second for USR2_TXDC to be set, we avoid a potential
deadlock.

In case of the timeout, there is not much we can do, so we simply ignore
the transmitter state and optimistically try to continue.

Signed-off-by: Esben Haabendal <esben@geanix.com>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/919647898c337a46604edcabaf13d42d80c0915d.1712837613.git.esben@geanix.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/tty/serial/imx.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index c77831e91ec20..a1476e47c6aab 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -26,6 +26,7 @@
 #include <linux/slab.h>
 #include <linux/of.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/dma-mapping.h>
 
 #include <asm/irq.h>
@@ -2009,7 +2010,7 @@ imx_uart_console_write(struct console *co, const char *s, unsigned int count)
 	struct imx_port *sport = imx_uart_ports[co->index];
 	struct imx_port_ucrs old_ucr;
 	unsigned long flags;
-	unsigned int ucr1;
+	unsigned int ucr1, usr2;
 	int locked = 1;
 
 	if (sport->port.sysrq)
@@ -2040,8 +2041,8 @@ imx_uart_console_write(struct console *co, const char *s, unsigned int count)
 	 *	Finally, wait for transmitter to become empty
 	 *	and restore UCR1/2/3
 	 */
-	while (!(imx_uart_readl(sport, USR2) & USR2_TXDC));
-
+	read_poll_timeout_atomic(imx_uart_readl, usr2, usr2 & USR2_TXDC,
+				 0, USEC_PER_SEC, false, sport, USR2);
 	imx_uart_ucrs_restore(sport, &old_ucr);
 
 	if (locked)
-- 
2.43.0

[PATCH AUTOSEL 6.6 12/20] serial: exar: adding missing CTI and Exar PCI ids

[Sasha Levin]

From: Parker Newman <pnewman@connecttech.com>

[ Upstream commit b86ae40ffcf5a16b9569b1016da4a08c4f352ca2 ]

- Added Connect Tech and Exar IDs not already in pci_ids.h

Signed-off-by: Parker Newman <pnewman@connecttech.com>
Link: https://lore.kernel.org/r/7c3d8e795a864dd9b0a00353b722060dc27c4e09.1713270624.git.pnewman@connecttech.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/tty/serial/8250/8250_exar.c | 42 +++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
index 4d20f3aa280cd..27430fdd9e761 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -41,8 +41,50 @@
 #define PCI_DEVICE_ID_COMMTECH_4228PCIE		0x0021
 #define PCI_DEVICE_ID_COMMTECH_4222PCIE		0x0022
 
+#define PCI_VENDOR_ID_CONNECT_TECH				0x12c4
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_SP_OPTO        0x0340
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_SP_OPTO_A      0x0341
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_SP_OPTO_B      0x0342
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_XPRS           0x0350
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_XPRS_A         0x0351
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_XPRS_B         0x0352
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_XPRS           0x0353
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_16_XPRS_A        0x0354
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_16_XPRS_B        0x0355
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_XPRS_OPTO      0x0360
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_XPRS_OPTO_A    0x0361
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_XPRS_OPTO_B    0x0362
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_SP             0x0370
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_SP_232         0x0371
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_SP_485         0x0372
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_4_SP           0x0373
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_6_2_SP           0x0374
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_6_SP           0x0375
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_SP_232_NS      0x0376
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_XP_OPTO_LEFT   0x0380
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_2_XP_OPTO_RIGHT  0x0381
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_XP_OPTO        0x0382
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_4_4_XPRS_OPTO    0x0392
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_XPRS_LP        0x03A0
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_XPRS_LP_232    0x03A1
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_XPRS_LP_485    0x03A2
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCI_UART_8_XPRS_LP_232_NS 0x03A3
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCIE_XEG001               0x0602
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCIE_XR35X_BASE           0x1000
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCIE_XR35X_2              0x1002
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCIE_XR35X_4              0x1004
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCIE_XR35X_8              0x1008
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCIE_XR35X_12             0x100C
+#define PCI_SUBDEVICE_ID_CONNECT_TECH_PCIE_XR35X_16             0x1010
+#define PCI_DEVICE_ID_CONNECT_TECH_PCI_XR79X_12_XIG00X          0x110c
+#define PCI_DEVICE_ID_CONNECT_TECH_PCI_XR79X_12_XIG01X          0x110d
+#define PCI_DEVICE_ID_CONNECT_TECH_PCI_XR79X_16                 0x1110
+
 #define PCI_DEVICE_ID_EXAR_XR17V4358		0x4358
 #define PCI_DEVICE_ID_EXAR_XR17V8358		0x8358
+#define PCI_DEVICE_ID_EXAR_XR17V252		0x0252
+#define PCI_DEVICE_ID_EXAR_XR17V254		0x0254
+#define PCI_DEVICE_ID_EXAR_XR17V258		0x0258
 
 #define PCI_SUBDEVICE_ID_USR_2980		0x0128
 #define PCI_SUBDEVICE_ID_USR_2981		0x0129
-- 
2.43.0

[PATCH AUTOSEL 6.6 15/20] tty: add the option to have a tty reject a new ldisc

[Sasha Levin]

From: Linus Torvalds <torvalds@linux-foundation.org>

[ Upstream commit 6bd23e0c2bb6c65d4f5754d1456bc9a4427fc59b ]

... and use it to limit the virtual terminals to just N_TTY.  They are
kind of special, and in particular, the "con_write()" routine violates
the "writes cannot sleep" rule that some ldiscs rely on.

This avoids the

   BUG: sleeping function called from invalid context at kernel/printk/printk.c:2659

when N_GSM has been attached to a virtual console, and gsmld_write()
calls con_write() while holding a spinlock, and con_write() then tries
to get the console lock.

Tested-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Daniel Starke <daniel.starke@siemens.com>
Reported-by: syzbot <syzbot+dbac96d8e73b61aa559c@syzkaller.appspotmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=dbac96d8e73b61aa559c
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20240423163339.59780-1-torvalds@linux-foundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/tty/tty_ldisc.c    |  6 ++++++
 drivers/tty/vt/vt.c        | 10 ++++++++++
 include/linux/tty_driver.h |  8 ++++++++
 3 files changed, 24 insertions(+)

diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c
index 3f68e213df1f7..d80e9d4c974b4 100644
--- a/drivers/tty/tty_ldisc.c
+++ b/drivers/tty/tty_ldisc.c
@@ -545,6 +545,12 @@ int tty_set_ldisc(struct tty_struct *tty, int disc)
 		goto out;
 	}
 
+	if (tty->ops->ldisc_ok) {
+		retval = tty->ops->ldisc_ok(tty, disc);
+		if (retval)
+			goto out;
+	}
+
 	old_ldisc = tty->ldisc;
 
 	/* Shutdown the old discipline. */
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index e66ff9c11dade..a22da757ca6d1 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -3390,6 +3390,15 @@ static void con_cleanup(struct tty_struct *tty)
 	tty_port_put(&vc->port);
 }
 
+/*
+ * We can't deal with anything but the N_TTY ldisc,
+ * because we can sleep in our write() routine.
+ */
+static int con_ldisc_ok(struct tty_struct *tty, int ldisc)
+{
+	return ldisc == N_TTY ? 0 : -EINVAL;
+}
+
 static int default_color           = 7; /* white */
 static int default_italic_color    = 2; // green (ASCII)
 static int default_underline_color = 3; // cyan (ASCII)
@@ -3509,6 +3518,7 @@ static const struct tty_operations con_ops = {
 	.resize = vt_resize,
 	.shutdown = con_shutdown,
 	.cleanup = con_cleanup,
+	.ldisc_ok = con_ldisc_ok,
 };
 
 static struct cdev vc0_cdev;
diff --git a/include/linux/tty_driver.h b/include/linux/tty_driver.h
index 18beff0cec1ab..b4f99f6a5385a 100644
--- a/include/linux/tty_driver.h
+++ b/include/linux/tty_driver.h
@@ -155,6 +155,13 @@ struct serial_struct;
  *
  *	Optional. Called under the @tty->termios_rwsem. May sleep.
  *
+ * @ldisc_ok: ``int ()(struct tty_struct *tty, int ldisc)``
+ *
+ *	This routine allows the @tty driver to decide if it can deal
+ *	with a particular @ldisc.
+ *
+ *	Optional. Called under the @tty->ldisc_sem and @tty->termios_rwsem.
+ *
  * @set_ldisc: ``void ()(struct tty_struct *tty)``
  *
  *	This routine allows the @tty driver to be notified when the device's
@@ -373,6 +380,7 @@ struct tty_operations {
 	void (*hangup)(struct tty_struct *tty);
 	int (*break_ctl)(struct tty_struct *tty, int state);
 	void (*flush_buffer)(struct tty_struct *tty);
+	int (*ldisc_ok)(struct tty_struct *tty, int ldisc);
 	void (*set_ldisc)(struct tty_struct *tty);
 	void (*wait_until_sent)(struct tty_struct *tty, int timeout);
 	void (*send_xchar)(struct tty_struct *tty, char ch);
-- 
2.43.0