Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit fe76fc6a authored by Ming Lei's avatar Ming Lei Committed by Linus Torvalds
Browse files

sbitmap: Protect swap_lock from hardirq 



Because we may call blk_mq_get_driver_tag() directly from
blk_mq_dispatch_rq_list() without holding any lock, then HARDIRQ may
come and the above DEADLOCK is triggered.

Commit ab53dcfb3e7b ("sbitmap: Protect swap_lock from hardirq") tries to
fix this issue by using 'spin_lock_bh', which isn't enough because we
complete request from hardirq context direclty in case of multiqueue.

Cc: Clark Williams <williams@redhat.com>
Fixes: ab53dcfb3e7b ("sbitmap: Protect swap_lock from hardirq")
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 37198768

lib/sbitmap.c

+3 −2
Original line number Diff line number Diff line
@@ -27,8 +27,9 @@ static inline bool sbitmap_deferred_clear(struct sbitmap *sb, int index) 
{

	unsigned long mask, val;

	bool ret = false;

	unsigned long flags;



	spin_lock_bh(&sb->map[index].swap_lock);

	spin_lock_irqsave(&sb->map[index].swap_lock, flags);



	if (!sb->map[index].cleared)

		goto out_unlock;
@@ -49,7 +50,7 @@ static inline bool sbitmap_deferred_clear(struct sbitmap *sb, int index) 


	ret = true;

out_unlock:

	spin_unlock_bh(&sb->map[index].swap_lock);

	spin_unlock_irqrestore(&sb->map[index].swap_lock, flags);

	return ret;

}