--- From e949c64fa6acbdaab999410250855a6a4fc6bad1 Mon Sep 17 00:00:00 2001 From: Stefan Bader Date: Mon, 18 Aug 2014 20:00:13 +0200 Subject: [PATCH] bcache: prevent crash on changing writeback_running commit a664d0f05a2e ("bcache: fix crash on shutdown in passthrough mode") 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 --- drivers/md/bcache/writeback.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/md/bcache/writeback.h +++ b/drivers/md/bcache/writeback.h @@ -63,7 +63,8 @@ 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)