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authorKent Overstreet <kmo@daterainc.com>2014-01-06 13:13:26 -0800
committerTejun Heo <tj@kernel.org>2014-01-21 04:40:56 -0500
commit687b0ad2751ca8ea418396fa780e22571fba76a8 (patch)
tree5603037cfd39eef273ec61186e37f9df000fce6f
parent6ce4eac1f600b34f2f7f58f9cd8f0503d79e42ae (diff)
downloadlinux-stericsson-687b0ad2751ca8ea418396fa780e22571fba76a8.tar.gz
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>
-rw-r--r--lib/percpu-refcount.c3
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);