From f309532bf3e1cc1b787403d84e3039812a7dbe50 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sat, 2 Jun 2012 15:21:43 -0700 Subject: tty: Revert the tty locking series, it needs more work This reverts the tty layer change to use per-tty locking, because it's not correct yet, and fixing it will require some more deep surgery. The main revert is d29f3ef39be4 ("tty_lock: Localise the lock"), but there are several smaller commits that built upon it, they also get reverted here. The list of reverted commits is: fde86d310886 - tty: add lockdep annotations 8f6576ad476b - tty: fix ldisc lock inversion trace d3ca8b64b97e - pty: Fix lock inversion b1d679afd766 - tty: drop the pty lock during hangup abcefe5fc357 - tty/amiserial: Add missing argument for tty_unlock() fd11b42e3598 - cris: fix missing tty arg in wait_event_interruptible_tty call d29f3ef39be4 - tty_lock: Localise the lock The revert had a trivial conflict in the 68360serial.c staging driver that got removed in the meantime. Signed-off-by: Linus Torvalds --- drivers/tty/tty_mutex.c | 71 +++++++++++-------------------------------------- 1 file changed, 15 insertions(+), 56 deletions(-) (limited to 'drivers/tty/tty_mutex.c') diff --git a/drivers/tty/tty_mutex.c b/drivers/tty/tty_mutex.c index 67feac9e6ebb..9ff986c32a21 100644 --- a/drivers/tty/tty_mutex.c +++ b/drivers/tty/tty_mutex.c @@ -4,70 +4,29 @@ #include #include -/* Legacy tty mutex glue */ - -enum { - TTY_MUTEX_NORMAL, - TTY_MUTEX_NESTED, -}; +/* + * The 'big tty mutex' + * + * This mutex is taken and released by tty_lock() and tty_unlock(), + * replacing the older big kernel lock. + * It can no longer be taken recursively, and does not get + * released implicitly while sleeping. + * + * Don't use in new code. + */ +static DEFINE_MUTEX(big_tty_mutex); /* * Getting the big tty mutex. */ - -static void __lockfunc tty_lock_nested(struct tty_struct *tty, - unsigned int subclass) +void __lockfunc tty_lock(void) { - if (tty->magic != TTY_MAGIC) { - printk(KERN_ERR "L Bad %p\n", tty); - WARN_ON(1); - return; - } - tty_kref_get(tty); - mutex_lock_nested(&tty->legacy_mutex, subclass); -} - -void __lockfunc tty_lock(struct tty_struct *tty) -{ - return tty_lock_nested(tty, TTY_MUTEX_NORMAL); + mutex_lock(&big_tty_mutex); } EXPORT_SYMBOL(tty_lock); -void __lockfunc tty_unlock(struct tty_struct *tty) +void __lockfunc tty_unlock(void) { - if (tty->magic != TTY_MAGIC) { - printk(KERN_ERR "U Bad %p\n", tty); - WARN_ON(1); - return; - } - mutex_unlock(&tty->legacy_mutex); - tty_kref_put(tty); + mutex_unlock(&big_tty_mutex); } EXPORT_SYMBOL(tty_unlock); - -/* - * Getting the big tty mutex for a pair of ttys with lock ordering - * On a non pty/tty pair tty2 can be NULL which is just fine. - */ -void __lockfunc tty_lock_pair(struct tty_struct *tty, - struct tty_struct *tty2) -{ - if (tty < tty2) { - tty_lock(tty); - tty_lock_nested(tty2, TTY_MUTEX_NESTED); - } else { - if (tty2 && tty2 != tty) - tty_lock(tty2); - tty_lock_nested(tty, TTY_MUTEX_NESTED); - } -} -EXPORT_SYMBOL(tty_lock_pair); - -void __lockfunc tty_unlock_pair(struct tty_struct *tty, - struct tty_struct *tty2) -{ - tty_unlock(tty); - if (tty2 && tty2 != tty) - tty_unlock(tty2); -} -EXPORT_SYMBOL(tty_unlock_pair); -- cgit v1.2.3