Merge tag 'v5.9-rc4' into drm-next

Backmerge 5.9-rc4 as there is a nasty qxl conflict
that needs to be resolved.

Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index a19cdf159b75..d2790e5b06d1 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -78,6 +78,15 @@ void blk_mq_sched_restart(struct blk_mq_hw_ctx *hctx)
 		return;
 	clear_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
 
+	/*
+	 * Order clearing SCHED_RESTART and list_empty_careful(&hctx->dispatch)
+	 * in blk_mq_run_hw_queue(). Its pair is the barrier in
+	 * blk_mq_dispatch_rq_list(). So dispatch code won't see SCHED_RESTART,
+	 * meantime new request added to hctx->dispatch is missed to check in
+	 * blk_mq_run_hw_queue().
+	 */
+	smp_mb();
+
 	blk_mq_run_hw_queue(hctx, true);
 }