From: Ming Lei <ming.lei@redhat.com>
To: John Garry <john.garry@huawei.com>
Cc: axboe@kernel.dk, osandov@fb.com, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] blk-mq-sched: Fix blk_mq_sched_alloc_tags() error handling
Date: Tue, 27 Jul 2021 18:06:46 +0800 [thread overview]
Message-ID: <YP/atlyuacbHF/sp@T590> (raw)
In-Reply-To: <1627378373-148090-1-git-send-email-john.garry@huawei.com>
On Tue, Jul 27, 2021 at 05:32:53PM +0800, John Garry wrote:
> If the blk_mq_sched_alloc_tags() -> blk_mq_alloc_rqs() call fails, then we
> call blk_mq_sched_free_tags() -> blk_mq_free_rqs().
>
> It is incorrect to do so, as any rqs would have already been freed in the
> blk_mq_alloc_rqs() call.
>
> Fix by calling blk_mq_free_rq_map() only directly.
>
> Fixes: 6917ff0b5bd41 ("blk-mq-sched: refactor scheduler initialization")
> Signed-off-by: John Garry <john.garry@huawei.com>
Not sure it is one fix, because blk_mq_free_rqs() does nothing when
->static_rqs[] isn't filled, so 'Fixes' tag isn't needed, IMO.
>
> diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
> index c838d81ac058..0f006cabfd91 100644
> --- a/block/blk-mq-sched.c
> +++ b/block/blk-mq-sched.c
> @@ -515,17 +515,6 @@ void blk_mq_sched_insert_requests(struct blk_mq_hw_ctx *hctx,
> percpu_ref_put(&q->q_usage_counter);
> }
>
> -static void blk_mq_sched_free_tags(struct blk_mq_tag_set *set,
> - struct blk_mq_hw_ctx *hctx,
> - unsigned int hctx_idx)
> -{
> - if (hctx->sched_tags) {
> - blk_mq_free_rqs(set, hctx->sched_tags, hctx_idx);
> - blk_mq_free_rq_map(hctx->sched_tags, set->flags);
> - hctx->sched_tags = NULL;
> - }
> -}
> -
> static int blk_mq_sched_alloc_tags(struct request_queue *q,
> struct blk_mq_hw_ctx *hctx,
> unsigned int hctx_idx)
> @@ -539,8 +528,10 @@ static int blk_mq_sched_alloc_tags(struct request_queue *q,
> return -ENOMEM;
>
> ret = blk_mq_alloc_rqs(set, hctx->sched_tags, hctx_idx, q->nr_requests);
> - if (ret)
> - blk_mq_sched_free_tags(set, hctx, hctx_idx);
> + if (ret) {
> + blk_mq_free_rq_map(hctx->sched_tags, set->flags);
> + hctx->sched_tags = NULL;
> + }
The patch itself looks fine:
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Thanks,
Ming
next prev parent reply other threads:[~2021-07-27 10:06 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-27 9:32 [PATCH] blk-mq-sched: Fix blk_mq_sched_alloc_tags() error handling John Garry
2021-07-27 10:06 ` Ming Lei [this message]
2021-07-27 10:30 ` John Garry
2021-07-27 10:43 ` Ming Lei
2021-07-27 22:44 ` Jens Axboe
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