From: Peter Zijlstra <pet...@infradead.org>
[ Upstream commit 7fb4a2cea6b18dab56d609530d077f168169ed6b ]
Boqun reported that hlock->references can overflow. Add a debug test
for that to generate a clear error when this happens.
Without this, lockdep is likely to report a mysterious failure on
unlock.
Reported-by: Boqun Feng <boqun.f...@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Nicolai Hähnle <nicolai.haeh...@amd.com>
Cc: Paul E. McKenney <paul...@linux.vnet.ibm.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mi...@kernel.org>
Signed-off-by: Sasha Levin <alexander.le...@verizon.com>
---
kernel/locking/lockdep.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 60ace56618f6..0e2c4911ba61 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3128,10 +3128,17 @@ static int __lock_acquire(struct lockdep_map *lock,
unsigned int subclass,
if (depth) {
hlock = curr->held_locks + depth - 1;
if (hlock->class_idx == class_idx && nest_lock) {
- if (hlock->references)
+ if (hlock->references) {
+ /*
+ * Check: unsigned int references:12, overflow.
+ */
+ if (DEBUG_LOCKS_WARN_ON(hlock->references == (1
<< 12)-1))
+ return 0;
+
hlock->references++;
- else
+ } else {
hlock->references = 2;
+ }
return 1;
}
--
2.11.0
