From fde86d310886372a377213251e72fb87aaa406c9 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 31 May 2012 11:35:18 +0200 Subject: [PATCH] tty: add lockdep annotations tty_lock_pair() do the right thing to avoid deadlocks, but should instruct LOCKDEP of this to avoid a splat. Signed-off-by: Eric Dumazet Signed-off-by: Linus Torvalds --- drivers/tty/tty_mutex.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/drivers/tty/tty_mutex.c b/drivers/tty/tty_mutex.c index 69adc80c98cd..67feac9e6ebb 100644 --- a/drivers/tty/tty_mutex.c +++ b/drivers/tty/tty_mutex.c @@ -6,11 +6,17 @@ /* Legacy tty mutex glue */ +enum { + TTY_MUTEX_NORMAL, + TTY_MUTEX_NESTED, +}; + /* * Getting the big tty mutex. */ -void __lockfunc tty_lock(struct tty_struct *tty) +static void __lockfunc tty_lock_nested(struct tty_struct *tty, + unsigned int subclass) { if (tty->magic != TTY_MAGIC) { printk(KERN_ERR "L Bad %p\n", tty); @@ -18,7 +24,12 @@ void __lockfunc tty_lock(struct tty_struct *tty) return; } tty_kref_get(tty); - mutex_lock(&tty->legacy_mutex); + mutex_lock_nested(&tty->legacy_mutex, subclass); +} + +void __lockfunc tty_lock(struct tty_struct *tty) +{ + return tty_lock_nested(tty, TTY_MUTEX_NORMAL); } EXPORT_SYMBOL(tty_lock); @@ -43,11 +54,11 @@ void __lockfunc tty_lock_pair(struct tty_struct *tty, { if (tty < tty2) { tty_lock(tty); - tty_lock(tty2); + tty_lock_nested(tty2, TTY_MUTEX_NESTED); } else { if (tty2 && tty2 != tty) tty_lock(tty2); - tty_lock(tty); + tty_lock_nested(tty, TTY_MUTEX_NESTED); } } EXPORT_SYMBOL(tty_lock_pair); -- 2.34.1