diff options
| author | Alan Cox <alan@linux.intel.com> | 2009-07-16 16:05:08 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-07-16 09:19:16 -0700 |
| commit | c8d50041734534e0a4b0ea13df36ed5857fccd56 (patch) | |
| tree | c654fde94ba2fbf1eb936f017d687860aed0deed | |
| parent | a3ca86aea507904148870946d599e07a340b39bf (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>
| -rw-r--r-- | drivers/char/tty_ldisc.c | 25 |
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) |