Re: [PATCH] blk-mq-sched: Fix blk_mq_sched_alloc_tags() error handling
From: Ming Lei <hidden>
Date: 2021-07-27 10:07:02
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lkml
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 <redacted>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.
quoted hunk ↗ jump to hunk
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 <redacted> Thanks, Ming