[PATCH] bcache: prevent crash on changing writeback_running

From: Stefan Bader
Date: Mon Aug 18 2014 - 14:00:13 EST


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 <stefan.bader@xxxxxxxxxxxxx>
---
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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/