| From | Kamal Mostafa <> | Subject | [PATCH 3.19.y-ckt 062/210] bcache: prevent crash on changing writeback_running | Date | Thu, 28 Jan 2016 17:16:40 -0800 |
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3.19.8-ckt14 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: Stefan Bader <stefan.bader@canonical.com>
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 <stefan.bader@canonical.com> Cc: Kent Overstreet <kent.overstreet@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/md/bcache/writeback.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
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) -- 1.9.1
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