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locking/lockdep: Add nest_lock integrity test

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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>
This commit is contained in:
Peter Zijlstra 2017-03-01 16:23:30 +01:00 committed by Ingo Molnar
parent 2b232e0c3b
commit 7fb4a2cea6
1 changed files with 9 additions and 2 deletions
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11
kernel/locking/lockdep.c
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@ -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;
}