sbitmap: Protect swap_lock from hardirq

fe76fc6a · Ming Lei <[email protected]> · 2019-01-15 11:59:52 +08:00

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 <[email protected]>
Fixes: ab53dcfb3e7b ("sbitmap: Protect swap_lock from hardirq")
Cc: Jens Axboe <[email protected]>
Cc: Ming Lei <[email protected]>
Cc: Guenter Roeck <[email protected]>
Cc: Steven Rostedt (VMware) <[email protected]>
Signed-off-by: Ming Lei <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: fe76fc6aaf538df27708ffa3e5d549a6c8e16142
Parents: 37198768

Changes

1 files changed · +3 −2

File	Status	Add	Del	Content
lib/sbitmap.c	modified	+3	−2	View file

lib/sbitmap.c

View file

diff --git a/lib/sbitmap.c b/lib/sbitmap.c
index 8643540..5b382c1 100644
--- 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;
 }
 