From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kent Overstreet Subject: [PATCH 12/12] closures: fix a race on wakeup from closure_sync Date: Mon, 10 Jun 2019 15:14:20 -0400 Message-ID: <20190610191420.27007-13-kent.overstreet@gmail.com> References: <20190610191420.27007-1-kent.overstreet@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190610191420.27007-1-kent.overstreet@gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-bcache@vger.kernel.org Cc: Kent Overstreet List-Id: linux-bcache@vger.kernel.org Signed-off-by: Kent Overstreet --- lib/closure.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/lib/closure.c b/lib/closure.c index 46cfe4c382..3e6366c262 100644 --- a/lib/closure.c +++ b/lib/closure.c @@ -104,8 +104,14 @@ struct closure_syncer { static void closure_sync_fn(struct closure *cl) { - cl->s->done = 1; - wake_up_process(cl->s->task); + struct closure_syncer *s = cl->s; + struct task_struct *p; + + rcu_read_lock(); + p = READ_ONCE(s->task); + s->done = 1; + wake_up_process(p); + rcu_read_unlock(); } void __sched __closure_sync(struct closure *cl) -- 2.20.1