Commit 687b0ad2 authored by Kent Overstreet's avatar Kent Overstreet Committed by Tejun Heo

percpu-refcount: Add a WARN() for ref going negative

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.

tj: Used WARN_ONCE() instead of WARN().
Signed-off-by: default avatarKent Overstreet <kmo@daterainc.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
parent 6ce4eac1
...@@ -120,6 +120,9 @@ static void percpu_ref_kill_rcu(struct rcu_head *rcu) ...@@ -120,6 +120,9 @@ static void percpu_ref_kill_rcu(struct rcu_head *rcu)
atomic_add((int) count - PCPU_COUNT_BIAS, &ref->count); atomic_add((int) count - PCPU_COUNT_BIAS, &ref->count);
WARN_ONCE(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 */ /* @ref is viewed as dead on all CPUs, send out kill confirmation */
if (ref->confirm_kill) if (ref->confirm_kill)
ref->confirm_kill(ref); ref->confirm_kill(ref);
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment