Messages in this thread Patch in this message | | | From | Kent Overstreet <> | Subject | [PATCH] percpu-refcount: Add a WARN() for ref going negative | Date | Mon, 6 Jan 2014 13:13:26 -0800 |
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AIO had a missing get, which led to an ioctx leak - after percpu_ref_kill() the ref was 0 so percpu_ref_put() never saw it hit 0.
This wasn't noticed at the time because it all happened completely silently, this adds a WARN() which would've caught the aio bug.
Signed-off-by: Kent Overstreet <kmo@daterainc.com> Cc: Tejun Heo <tj@kernel.org> --- lib/percpu-refcount.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c index 1a53d497a8..32538f12f8 100644 --- a/lib/percpu-refcount.c +++ b/lib/percpu-refcount.c @@ -120,6 +120,9 @@ static void percpu_ref_kill_rcu(struct rcu_head *rcu) atomic_add((int) count - PCPU_COUNT_BIAS, &ref->count); + WARN(atomic_read(&ref->count) <= 0, + "percpu ref <= 0 (%i)", atomic_read(&ref->count)); + /* @ref is viewed as dead on all CPUs, send out kill confirmation */ if (ref->confirm_kill) ref->confirm_kill(ref); -- 1.8.5.2
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