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 <stable@xxxxxxxxxxxxxxx> know about it.
>From 0bfd464d3fdd5bb322f9cace4cc47f1796545cf7 Mon Sep 17 00:00:00 2001
From: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
Date: Sat, 9 Jan 2016 21:13:44 -0800
Subject: tty: Wait interruptibly for tty lock on reopen
From: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
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 <peter@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/tty_io.c | 8 +++++++-
drivers/tty/tty_mutex.c | 8 ++++++++
include/linux/tty.h | 1 +
3 files changed, 16 insertions(+), 1 deletion(-)
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -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);
--- a/drivers/tty/tty_mutex.c
+++ b/drivers/tty/tty_mutex.c
@@ -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) {
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -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 peter@xxxxxxxxxxxxxxxxxx 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
--
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