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tty: Wait interruptibly for tty lock on reopen

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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@hurleysoftware.com>
Cc: stable <stable@vger.kernel.org> # 4.4
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Hurley 2016-01-09 21:13:44 -08:00 • committed by Greg Kroah-Hartman
parent 92e963f50f
commit 0bfd464d3f
3 changed files with 16 additions and 1 deletions
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8
drivers/tty/tty_io.c
View file

@ -2065,7 +2065,12 @@ retry_open:
if (tty) { if (tty) {
mutex_unlock(&tty_mutex); 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() */ /* safe to drop the kref from tty_driver_lookup_tty() */
tty_kref_put(tty); tty_kref_put(tty);
retval = tty_reopen(tty); retval = tty_reopen(tty);
@ -2152,6 +2157,7 @@ retry_open:
return 0; return 0;
err_unlock: err_unlock:
mutex_unlock(&tty_mutex); mutex_unlock(&tty_mutex);
err_unref:
/* after locks to avoid deadlock */ /* after locks to avoid deadlock */
if (!IS_ERR_OR_NULL(driver)) if (!IS_ERR_OR_NULL(driver))
tty_driver_kref_put(driver); tty_driver_kref_put(driver);

8
drivers/tty/tty_mutex.c
View file

@ -19,6 +19,14 @@ void __lockfunc tty_lock(struct tty_struct *tty)
} }
EXPORT_SYMBOL(tty_lock); 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) void __lockfunc tty_unlock(struct tty_struct *tty)
{ {
if (WARN(tty->magic != TTY_MAGIC, "U Bad %p\n", tty)) if (WARN(tty->magic != TTY_MAGIC, "U Bad %p\n", tty))

1
include/linux/tty.h
View file

@ -649,6 +649,7 @@ extern long vt_compat_ioctl(struct tty_struct *tty,
/* tty_mutex.c */ /* tty_mutex.c */
/* functions for preparation of BKL removal */ /* functions for preparation of BKL removal */
extern void __lockfunc tty_lock(struct tty_struct *tty); 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_unlock(struct tty_struct *tty);
extern void __lockfunc tty_lock_slave(struct tty_struct *tty); extern void __lockfunc tty_lock_slave(struct tty_struct *tty);
extern void __lockfunc tty_unlock_slave(struct tty_struct *tty); extern void __lockfunc tty_unlock_slave(struct tty_struct *tty);