From d29f3ef39be4eec0362b985305fc526d9be318cf Mon Sep 17 00:00:00 2001 From: Alan Cox Date: Thu, 3 May 2012 22:24:08 +0100 Subject: tty_lock: Localise the lock In each remaining case the tty_lock is associated with a specific tty. This means we can now lock on a per tty basis. We do need tty_lock_pair() for the pty case. Uglier but still a step in the right direction. [fixed up calls in 3 missing drivers - gregkh] Signed-off-by: Alan Cox Acked-by: Arnd Bergmann Signed-off-by: Greg Kroah-Hartman --- drivers/tty/tty_mutex.c | 60 ++++++++++++++++++++++++++++++++++++------------- 1 file changed, 45 insertions(+), 15 deletions(-) (limited to 'drivers/tty/tty_mutex.c') diff --git a/drivers/tty/tty_mutex.c b/drivers/tty/tty_mutex.c index 9ff986c32a21..69adc80c98cd 100644 --- a/drivers/tty/tty_mutex.c +++ b/drivers/tty/tty_mutex.c @@ -4,29 +4,59 @@ #include #include -/* - * 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); +/* Legacy tty mutex glue */ /* * Getting the big tty mutex. */ -void __lockfunc tty_lock(void) + +void __lockfunc tty_lock(struct tty_struct *tty) { - mutex_lock(&big_tty_mutex); + if (tty->magic != TTY_MAGIC) { + printk(KERN_ERR "L Bad %p\n", tty); + WARN_ON(1); + return; + } + tty_kref_get(tty); + mutex_lock(&tty->legacy_mutex); } EXPORT_SYMBOL(tty_lock); -void __lockfunc tty_unlock(void) +void __lockfunc tty_unlock(struct tty_struct *tty) { - mutex_unlock(&big_tty_mutex); + 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); } 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(tty2); + } else { + if (tty2 && tty2 != tty) + tty_lock(tty2); + tty_lock(tty); + } +} +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