[PATCH 13/13] tty: turn ldisc_mutex into a regular mutex
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From: Arnd Bergmann on 4 May 2010 18:40 This fixes the lock order of the BTM and ldisc_mutex so that we never take the BTM while holding ldisc_mutex, which means we no longer have to use mutex_lock_tty when getting ldisc_mutex. Signed-off-by: Arnd Bergmann <arnd(a)arndb.de> --- drivers/char/tty_io.c | 2 +- drivers/char/tty_ldisc.c | 15 ++++++++------- 2 files changed, 9 insertions(+), 8 deletions(-) diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c index 4e16b34..80178cc 100644 --- a/drivers/char/tty_io.c +++ b/drivers/char/tty_io.c @@ -1289,7 +1289,7 @@ static int tty_reopen(struct tty_struct *tty) tty->count++; tty->driver = driver; /* N.B. why do this every time?? */ - mutex_lock_tty_on(&tty->ldisc_mutex); + mutex_lock(&tty->ldisc_mutex); WARN_ON(!test_bit(TTY_LDISC, &tty->flags)); mutex_unlock(&tty->ldisc_mutex); diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c index 0c0e935..dda31b0 100644 --- a/drivers/char/tty_ldisc.c +++ b/drivers/char/tty_ldisc.c @@ -598,7 +598,8 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc) tty_wait_until_sent(tty, 0); - mutex_lock_tty_off(&tty->ldisc_mutex); + tty_lock(); + mutex_lock(&tty->ldisc_mutex); /* * We could be midstream of another ldisc change which has @@ -607,13 +608,13 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc) while (test_bit(TTY_LDISC_CHANGING, &tty->flags)) { mutex_unlock(&tty->ldisc_mutex); + tty_unlock(); wait_event(tty_ldisc_wait, test_bit(TTY_LDISC_CHANGING, &tty->flags) == 0); - mutex_lock_tty_off(&tty->ldisc_mutex); + tty_lock(); + mutex_lock(&tty->ldisc_mutex); } - tty_lock(); - set_bit(TTY_LDISC_CHANGING, &tty->flags); /* @@ -650,8 +651,8 @@ int tty_set_ldisc(struct tty_struct *tty, int ldisc) flush_scheduled_work(); - mutex_lock_tty_off(&tty->ldisc_mutex); tty_lock(); + mutex_lock(&tty->ldisc_mutex); if (test_bit(TTY_HUPPED, &tty->flags)) { /* We were raced by the hangup method. It will have stomped the ldisc data and closed the ldisc down */ @@ -797,7 +798,7 @@ void tty_ldisc_hangup(struct tty_struct *tty) * * Avoid racing set_ldisc or tty_ldisc_release */ - mutex_lock_tty_on(&tty->ldisc_mutex); + mutex_lock(&tty->ldisc_mutex); tty_ldisc_halt(tty); /* At this point we have a closed ldisc and we want to reopen it. We could defer this to the next open but @@ -873,7 +874,7 @@ void tty_ldisc_release(struct tty_struct *tty, struct tty_struct *o_tty) tty_unlock(); flush_scheduled_work(); tty_lock(); - mutex_lock_tty_on(&tty->ldisc_mutex); + mutex_lock(&tty->ldisc_mutex); /* * Now kill off the ldisc */ -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |