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authorAlan Cox <alan@linux.intel.com>2009-07-16 16:05:08 +0100
committerLinus Torvalds <torvalds@linux-foundation.org>2009-07-16 09:19:16 -0700
commitc8d50041734534e0a4b0ea13df36ed5857fccd56 (patch)
treec654fde94ba2fbf1eb936f017d687860aed0deed /drivers/char
parenta3ca86aea507904148870946d599e07a340b39bf (diff)
tty: fix close/hangup race
We can get a situation where a hangup occurs during or after a close. In that case the ldisc gets disposed of by the close and the hangup then explodes. Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/tty_ldisc.c25
1 files changed, 15 insertions, 10 deletions
diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index 0ef0dc97ba2..acd76b767d4 100644
--- a/drivers/char/tty_ldisc.c
+++ b/drivers/char/tty_ldisc.c
@@ -790,17 +790,20 @@ void tty_ldisc_hangup(struct tty_struct *tty)
* N_TTY.
*/
if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
- /* Avoid racing set_ldisc */
+ /* Avoid racing set_ldisc or tty_ldisc_release */
mutex_lock(&tty->ldisc_mutex);
- /* Switch back to N_TTY */
- tty_ldisc_halt(tty);
- tty_ldisc_wait_idle(tty);
- tty_ldisc_reinit(tty);
- /* At this point we have a closed ldisc and we want to
- reopen it. We could defer this to the next open but
- it means auditing a lot of other paths so this is a FIXME */
- WARN_ON(tty_ldisc_open(tty, tty->ldisc));
- tty_ldisc_enable(tty);
+ if (tty->ldisc) { /* Not yet closed */
+ /* Switch back to N_TTY */
+ tty_ldisc_halt(tty);
+ tty_ldisc_wait_idle(tty);
+ tty_ldisc_reinit(tty);
+ /* At this point we have a closed ldisc and we want to
+ reopen it. We could defer this to the next open but
+ it means auditing a lot of other paths so this is
+ a FIXME */
+ WARN_ON(tty_ldisc_open(tty, tty->ldisc));
+ tty_ldisc_enable(tty);
+ }
mutex_unlock(&tty->ldisc_mutex);
tty_reset_termios(tty);
}
@@ -865,6 +868,7 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
tty_ldisc_wait_idle(tty);
+ mutex_lock(&tty->ldisc_mutex);
/*
* Now kill off the ldisc
*/
@@ -875,6 +879,7 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty)
/* Ensure the next open requests the N_TTY ldisc */
tty_set_termios_ldisc(tty, N_TTY);
+ mutex_unlock(&tty->ldisc_mutex);
/* This will need doing differently if we need to lock */
if (o_tty)