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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Ming Lei <ming.lei@redhat.com>,
	linux-scsi@vger.kernel.org,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	luojiaxing <luojiaxing@huawei.com>, Jens Axboe <axboe@kernel.dk>,
	Sasha Levin <sashal@kernel.org>,
	linux-block@vger.kernel.org
Subject: [PATCH AUTOSEL 5.10 05/26] blk-mq: avoid to iterate over stale request
Date: Wed, 22 Sep 2021 23:38:18 -0400	[thread overview]
Message-ID: <20210923033839.1421034-5-sashal@kernel.org> (raw)
In-Reply-To: <20210923033839.1421034-1-sashal@kernel.org>

From: Ming Lei <ming.lei@redhat.com>

[ Upstream commit 67f3b2f822b7e71cfc9b42dbd9f3144fa2933e0b ]

blk-mq can't run allocating driver tag and updating ->rqs[tag]
atomically, meantime blk-mq doesn't clear ->rqs[tag] after the driver
tag is released.

So there is chance to iterating over one stale request just after the
tag is allocated and before updating ->rqs[tag].

scsi_host_busy_iter() calls scsi_host_check_in_flight() to count scsi
in-flight requests after scsi host is blocked, so no new scsi command can
be marked as SCMD_STATE_INFLIGHT. However, driver tag allocation still can
be run by blk-mq core. One request is marked as SCMD_STATE_INFLIGHT,
but this request may have been kept in another slot of ->rqs[], meantime
the slot can be allocated out but ->rqs[] isn't updated yet. Then this
in-flight request is counted twice as SCMD_STATE_INFLIGHT. This way causes
trouble in handling scsi error.

Fixes the issue by not iterating over stale request.

Cc: linux-scsi@vger.kernel.org
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Reported-by: luojiaxing <luojiaxing@huawei.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20210906065003.439019-1-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 block/blk-mq-tag.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index c4f2f6c123ae..16ad9e656610 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -207,7 +207,7 @@ static struct request *blk_mq_find_and_get_req(struct blk_mq_tags *tags,
 
 	spin_lock_irqsave(&tags->lock, flags);
 	rq = tags->rqs[bitnr];
-	if (!rq || !refcount_inc_not_zero(&rq->ref))
+	if (!rq || rq->tag != bitnr || !refcount_inc_not_zero(&rq->ref))
 		rq = NULL;
 	spin_unlock_irqrestore(&tags->lock, flags);
 	return rq;
-- 
2.30.2


  parent reply	other threads:[~2021-09-23  3:39 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-23  3:38 [PATCH AUTOSEL 5.10 01/26] ibmvnic: check failover_pending in login response Sasha Levin
2021-09-23  3:38 ` [PATCH AUTOSEL 5.10 02/26] net: phylink: Update SFP selected interface on advertising changes Sasha Levin
2021-09-23  3:38 ` [PATCH AUTOSEL 5.10 03/26] net: macb: fix use after free on rmmod Sasha Levin
2021-09-23  3:38 ` [PATCH AUTOSEL 5.10 04/26] net: stmmac: allow CSR clock of 300MHz Sasha Levin
2021-09-23  3:38 ` Sasha Levin [this message]
2021-09-23  3:38 ` [PATCH AUTOSEL 5.10 06/26] m68k: Double cast io functions to unsigned long Sasha Levin
2021-09-23  3:38 ` [PATCH AUTOSEL 5.10 07/26] ipv6: delay fib6_sernum increase in fib6_add Sasha Levin
2021-09-23  7:33 ` [PATCH AUTOSEL 5.10 01/26] ibmvnic: check failover_pending in login response Pavel Machek
2021-09-24 11:47   ` Sasha Levin

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