From fe76fc6aaf538df27708ffa3e5d549a6c8e16142 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Tue, 15 Jan 2019 11:59:52 +0800 Subject: [PATCH] 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 Fixes: ab53dcfb3e7b ("sbitmap: Protect swap_lock from hardirq") Cc: Jens Axboe Cc: Ming Lei Cc: Guenter Roeck Cc: Steven Rostedt (VMware) Signed-off-by: Ming Lei Signed-off-by: Linus Torvalds --- lib/sbitmap.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/lib/sbitmap.c b/lib/sbitmap.c index 864354000e04..5b382c1244ed 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; }