[PATCH 5.10 078/118] block, bfq: protect bfqd->queued by bfqd->lock

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From: Yu Kuai <yukuai3@xxxxxxxxxx>

commit 181490d5321806e537dc5386db5ea640b826bf78 upstream.

If bfq_schedule_dispatch() is called from bfq_idle_slice_timer_body(),
then 'bfqd->queued' is read without holding 'bfqd->lock'. This is
wrong since it can be wrote concurrently.

Fix the problem by holding 'bfqd->lock' in such case.

Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Reviewed-by: Chaitanya Kulkarni <kch@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220513023507.2625717-2-yukuai3@xxxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Cc: Khazhy Kumykov <khazhy@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 block/bfq-iosched.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -421,6 +421,8 @@ static struct bfq_io_cq *bfq_bic_lookup(
  */
 void bfq_schedule_dispatch(struct bfq_data *bfqd)
 {
+	lockdep_assert_held(&bfqd->lock);
+
 	if (bfqd->queued != 0) {
 		bfq_log(bfqd, "schedule dispatch");
 		blk_mq_run_hw_queues(bfqd->queue, true);
@@ -6269,8 +6271,8 @@ bfq_idle_slice_timer_body(struct bfq_dat
 	bfq_bfqq_expire(bfqd, bfqq, true, reason);
 
 schedule_dispatch:
-	spin_unlock_irqrestore(&bfqd->lock, flags);
 	bfq_schedule_dispatch(bfqd);
+	spin_unlock_irqrestore(&bfqd->lock, flags);
 }
 
 /*





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