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authorPeter Zijlstra <peterz@infradead.org>2017-03-01 16:23:30 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-10-21 17:21:33 +0200
commit8b0be545deba980344915b67ee39dd6b5b0b2e76 (patch)
treedf87fe3fb121cb9764180694a0fdec38b5cd201c /kernel
parent43588be0735f78b4fbbcbae1e8234a5d4620c191 (diff)
locking/lockdep: Add nest_lock integrity test
[ 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.feng@gmail.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Nicolai Hähnle <Nicolai.Haehnle@amd.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/locking/lockdep.c11
1 files changed, 9 insertions, 2 deletions
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 4d7ffc0a0d00..6599c7f3071d 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -3260,10 +3260,17 @@ 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;
}