From: Stefan Bader Date: Mon, 30 Nov 2015 02:44:49 +0000 (-0800) Subject: bcache: prevent crash on changing writeback_running X-Git-Tag: v4.1.18~176 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ad148665b58dcd0a4336188ce4a2194d7f353c5f;p=platform%2Fkernel%2Flinux-exynos.git bcache: prevent crash on changing writeback_running [ Upstream commit 8d16ce540c94c9d366eb36fc91b7154d92d6397b ] Added a safeguard in the shutdown case. At least while not being attached it is also possible to trigger a kernel bug by writing into writeback_running. This change adds the same check before trying to wake up the thread for that case. Signed-off-by: Stefan Bader Cc: Kent Overstreet Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- diff --git a/drivers/md/bcache/writeback.h b/drivers/md/bcache/writeback.h index 0a9dab1..073a042 100644 --- a/drivers/md/bcache/writeback.h +++ b/drivers/md/bcache/writeback.h @@ -63,7 +63,8 @@ static inline bool should_writeback(struct cached_dev *dc, struct bio *bio, static inline void bch_writeback_queue(struct cached_dev *dc) { - wake_up_process(dc->writeback_thread); + if (!IS_ERR_OR_NULL(dc->writeback_thread)) + wake_up_process(dc->writeback_thread); } static inline void bch_writeback_add(struct cached_dev *dc)