From 83506c85f8d4332b3edfdc8f1fd07aa691415350 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 8 May 2024 19:45:29 +0200 Subject: Adding upstream version 5.10.216. Signed-off-by: Daniel Baumann --- block/blk-mq.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'block/blk-mq.c') diff --git a/block/blk-mq.c b/block/blk-mq.c index e153a36c9..a7a31d709 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1188,6 +1188,22 @@ static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx *hctx, wait->flags &= ~WQ_FLAG_EXCLUSIVE; __add_wait_queue(wq, wait); + /* + * Add one explicit barrier since blk_mq_get_driver_tag() may + * not imply barrier in case of failure. + * + * Order adding us to wait queue and allocating driver tag. + * + * The pair is the one implied in sbitmap_queue_wake_up() which + * orders clearing sbitmap tag bits and waitqueue_active() in + * __sbitmap_queue_wake_up(), since waitqueue_active() is lockless + * + * Otherwise, re-order of adding wait queue and getting driver tag + * may cause __sbitmap_queue_wake_up() to wake up nothing because + * the waitqueue_active() may not observe us in wait queue. + */ + smp_mb(); + /* * It's possible that a tag was freed in the window between the * allocation failure and adding the hardware queue to the wait -- cgit v1.2.3