[PATCH] disable debugging version of write_lock()
We've confirmed that the debug version of write_lock() can get stuck for long
enough to cause NMI watchdog timeouts and hence a crash.
We don't know why, yet. Disable it for now.
Also disable the similar read_lock() code. Just in case.
Thanks to Dave Olson <olson@unixfolk.com> for reporting and testing.
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/lib/spinlock_debug.c b/lib/spinlock_debug.c
index 3d9c4dc..58c577d 100644
--- a/lib/spinlock_debug.c
+++ b/lib/spinlock_debug.c
@@ -162,6 +162,7 @@
#define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
+#if 0 /* __write_lock_debug() can lock up - maybe this can too? */
static void __read_lock_debug(rwlock_t *lock)
{
int print_once = 1;
@@ -184,12 +185,12 @@
}
}
}
+#endif
void _raw_read_lock(rwlock_t *lock)
{
RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
- if (unlikely(!__raw_read_trylock(&lock->raw_lock)))
- __read_lock_debug(lock);
+ __raw_read_lock(&lock->raw_lock);
}
int _raw_read_trylock(rwlock_t *lock)
@@ -235,6 +236,7 @@
lock->owner_cpu = -1;
}
+#if 0 /* This can cause lockups */
static void __write_lock_debug(rwlock_t *lock)
{
int print_once = 1;
@@ -257,12 +259,12 @@
}
}
}
+#endif
void _raw_write_lock(rwlock_t *lock)
{
debug_write_lock_before(lock);
- if (unlikely(!__raw_write_trylock(&lock->raw_lock)))
- __write_lock_debug(lock);
+ __raw_write_lock(&lock->raw_lock);
debug_write_lock_after(lock);
}