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Patch "tty: Wait interruptibly for tty lock on reopen" has been added to the 4.4-stable tree

PATCH [email protected] 1 participant 1 message Feb 14, 2016

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This is a note to let you know that I've just added the patch titled

tty: Wait interruptibly for tty lock on reopen

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
tty-wait-interruptibly-for-tty-lock-on-reopen.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Quoted 1 line

From 0bfd464d3fdd5bb322f9cace4cc47f1796545cf7 Mon Sep 17 00:00:00 2001

From: Peter Hurley <[email protected]>
Date: Sat, 9 Jan 2016 21:13:44 -0800
Subject: tty: Wait interruptibly for tty lock on reopen

From: Peter Hurley <[email protected]>

commit 0bfd464d3fdd5bb322f9cace4cc47f1796545cf7 upstream.

Allow a signal to interrupt the wait for a tty reopen; eg., if the tty has starting final close and is waiting for the device to drain.

Signed-off-by Peter Hurley <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 drivers/tty/tty_io.c    |    8 +++++++-
 drivers/tty/tty_mutex.c |    8 ++++++++
 include/linux/tty.h     |    1 +
 3 files changed, 16 insertions(+), 1 deletion(-)
drivers/tty/tty_io.c +7 -1
@@ -2069,7 +2069,12 @@ retry_open:
 
 		if (tty) {
 			mutex_unlock(&tty_mutex);
-			tty_lock(tty);
+			retval = tty_lock_interruptible(tty);
+			if (retval) {
+				if (retval == -EINTR)
+					retval = -ERESTARTSYS;
+				goto err_unref;
+			}
 			/* safe to drop the kref from tty_driver_lookup_tty() */
 			tty_kref_put(tty);
 			retval = tty_reopen(tty);

@@ -2156,6 +2161,7 @@ retry_open:
 	return 0;
 err_unlock:
 	mutex_unlock(&tty_mutex);
+err_unref:
 	/* after locks to avoid deadlock */
 	if (!IS_ERR_OR_NULL(driver))
 		tty_driver_kref_put(driver);
drivers/tty/tty_mutex.c +8 -0
@@ -22,6 +22,14 @@ void __lockfunc tty_lock(struct tty_stru
 }
 EXPORT_SYMBOL(tty_lock);
 
+int tty_lock_interruptible(struct tty_struct *tty)
+{
+	if (WARN(tty->magic != TTY_MAGIC, "L Bad %p\n", tty))
+		return -EIO;
+	tty_kref_get(tty);
+	return mutex_lock_interruptible(&tty->legacy_mutex);
+}
+
 void __lockfunc tty_unlock(struct tty_struct *tty)
 {
 	if (tty->magic != TTY_MAGIC) {
include/linux/tty.h +1 -0
@@ -654,6 +654,7 @@ extern long vt_compat_ioctl(struct tty_s
 /* tty_mutex.c */
 /* functions for preparation of BKL removal */
 extern void __lockfunc tty_lock(struct tty_struct *tty);
+extern int  tty_lock_interruptible(struct tty_struct *tty);
 extern void __lockfunc tty_unlock(struct tty_struct *tty);
 extern void __lockfunc tty_lock_slave(struct tty_struct *tty);
 extern void __lockfunc tty_unlock_slave(struct tty_struct *tty);

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/tty-wait-interruptibly-for-tty-lock-on-reopen.patch queue-4.4/n_tty-fix-unsafe-reference-to-other-ldisc.patch queue-4.4/tty-fix-unsafe-ldisc-reference-via-ioctl-tiocgetd.patch queue-4.4/tty-retry-failed-reopen-if-tty-teardown-in-progress.patch