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>
diff --git a/drivers/tty/tty_mutex.c b/drivers/tty/tty_mutex.c
index 69adc80..67feac9 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 @@
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 @@
{
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);