diff options
| -rw-r--r-- | drivers/tty/tty_ldisc.c | 42 |
1 files changed, 24 insertions, 18 deletions
diff --git a/drivers/tty/tty_ldisc.c b/drivers/tty/tty_ldisc.c index f691c7604d9a..525ee535c10d 100644 --- a/drivers/tty/tty_ldisc.c +++ b/drivers/tty/tty_ldisc.c @@ -530,24 +530,38 @@ static int tty_ldisc_wait_idle(struct tty_struct *tty, long timeout) /** * tty_ldisc_halt - shut down the line discipline * @tty: tty device + * @pending: returns true if work was scheduled when cancelled + * (can be set to NULL) + * @timeout: # of jiffies to wait for ldisc refs to be released * * Shut down the line discipline and work queue for this tty device. * The TTY_LDISC flag being cleared ensures no further references can * be obtained while the delayed work queue halt ensures that no more * data is fed to the ldisc. * + * Furthermore, guarantee that existing ldisc references have been + * released, which in turn, guarantees that no future buffer work + * can be rescheduled. + * * You need to do a 'flush_scheduled_work()' (outside the ldisc_mutex) * in order to make sure any currently executing ldisc work is also * flushed. */ -static int tty_ldisc_halt(struct tty_struct *tty) +static int tty_ldisc_halt(struct tty_struct *tty, int *pending, long timeout) { - int scheduled; + int scheduled, retval; + clear_bit(TTY_LDISC, &tty->flags); + retval = tty_ldisc_wait_idle(tty, timeout); + if (retval) + return retval; + scheduled = cancel_work_sync(&tty->port->buf.work); set_bit(TTY_LDISC_HALTED, &tty->flags); - return scheduled; + if (pending) + *pending = scheduled; + return 0; } /** @@ -688,9 +702,9 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc) * parallel to the change and re-referencing the tty. */ - work = tty_ldisc_halt(tty); - if (o_tty) - o_work = tty_ldisc_halt(o_tty); + retval = tty_ldisc_halt(tty, &work, 5 * HZ); + if (!retval && o_tty) + retval = tty_ldisc_halt(o_tty, &o_work, 5 * HZ); /* * Wait for ->hangup_work and ->buf.work handlers to terminate. @@ -701,8 +715,6 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc) tty_ldisc_flush_works(tty); - retval = tty_ldisc_wait_idle(tty, 5 * HZ); - tty_lock(tty); mutex_lock(&tty->ldisc_mutex); @@ -921,11 +933,6 @@ int tty_ldisc_setup(struct tty_struct *tty, struct tty_struct *o_tty) static void tty_ldisc_kill(struct tty_struct *tty) { - /* There cannot be users from userspace now. But there still might be - * drivers holding a reference via tty_ldisc_ref. Do not steal them the - * ldisc until they are done. */ - tty_ldisc_wait_idle(tty, MAX_SCHEDULE_TIMEOUT); - mutex_lock(&tty->ldisc_mutex); /* * Now kill off the ldisc @@ -958,13 +965,12 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty) * race with the set_ldisc code path. */ - tty_ldisc_halt(tty); - if (o_tty) - tty_ldisc_halt(o_tty); - + tty_ldisc_halt(tty, NULL, MAX_SCHEDULE_TIMEOUT); tty_ldisc_flush_works(tty); - if (o_tty) + if (o_tty) { + tty_ldisc_halt(o_tty, NULL, MAX_SCHEDULE_TIMEOUT); tty_ldisc_flush_works(o_tty); + } tty_lock_pair(tty, o_tty); /* This will need doing differently if we need to lock */ |