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| author | Kent Overstreet <kmo@daterainc.com> | 2014-01-06 13:13:26 -0800 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2014-01-21 04:40:56 -0500 |
| commit | 687b0ad2751ca8ea418396fa780e22571fba76a8 (patch) | |
| tree | 5603037cfd39eef273ec61186e37f9df000fce6f /lib/percpu-refcount.c | |
| parent | 6ce4eac1f600b34f2f7f58f9cd8f0503d79e42ae (diff) | |
| download | lwn-687b0ad2751ca8ea418396fa780e22571fba76a8.tar.gz lwn-687b0ad2751ca8ea418396fa780e22571fba76a8.zip | |
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: Kent Overstreet <kmo@daterainc.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'lib/percpu-refcount.c')
| -rw-r--r-- | lib/percpu-refcount.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c index 1a53d497a8c5..963b7034a51b 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_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 */ if (ref->confirm_kill) ref->confirm_kill(ref); |