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: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index 864354000e04d65f12e9586a6cf80cad463a7117..5b382c1244ede33c14016142ac2d7fec4d0608da 100644 (file)
--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -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;
 }