From: Stefan Bader Date: Mon, 30 Nov 2015 02:44:49 +0000 (-0800) Subject: bcache: prevent crash on changing writeback_running X-Git-Tag: firefly_0821_release~176^2~475^2~350 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=9e761c1b436d04823baa161c294fddc524750015;p=firefly-linux-kernel-4.4.55.git bcache: prevent crash on changing writeback_running commit 8d16ce540c94c9d366eb36fc91b7154d92d6397b upstream. 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 Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/md/bcache/writeback.h b/drivers/md/bcache/writeback.h index 0a9dab187b79..073a042aed24 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)