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authorEric Dumazet <edumazet@google.com>2012-05-31 11:35:18 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-31 11:59:41 -0700
commitfde86d310886372a377213251e72fb87aaa406c9 (patch)
treed0131cf044535b71710dd61ee78b4810f5545ac3 /drivers
parent1d59d61f606547f0712aa6971f91f71154071c99 (diff)
downloadlinux-fde86d310886372a377213251e72fb87aaa406c9.tar.gz
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 <edumazet@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/tty/tty_mutex.c19
1 files changed, 15 insertions, 4 deletions
diff --git a/drivers/tty/tty_mutex.c b/drivers/tty/tty_mutex.c
index 69adc80c98c..67feac9e6eb 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);