linux-kernel - [PATCH 5.4 34/34] scsi: core: Fix race between handling STS

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Date:   Mon,  1 Aug 2022 13:47:14 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Hannes Reinecke <hare@...e.com>,
        Sumit Saxena <sumit.saxena@...adcom.com>,
        Kashyap Desai <kashyap.desai@...adcom.com>,
        Bart Van Assche <bvanassche@....org>,
        Ewan Milne <emilne@...hat.com>, Long Li <longli@...rosoft.com>,
        John Garry <john.garry@...wei.com>,
        "chenxiang (M)" <chenxiang66@...ilicon.com>,
        Ming Lei <ming.lei@...hat.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Yu Kuai <yukuai3@...wei.com>
Subject: [PATCH 5.4 34/34] scsi: core: Fix race between handling STS_RESOURCE and completion

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

commit 673235f915318ced5d7ec4b2bfd8cb909e6a4a55 upstream.

When queuing I/O request to LLD, STS_RESOURCE may be returned because:

 - Host is in recovery or blocked

 - Target queue throttling or target is blocked

 - LLD rejection

In these scenarios BLK_STS_DEV_RESOURCE is returned to the block layer to
avoid an unnecessary re-run of the queue. However, all of the requests
queued to this SCSI device may complete immediately after reading
'sdev->device_busy' and BLK_STS_DEV_RESOURCE is returned to block layer. In
that case the current I/O won't get a chance to get queued since it is
invisible at that time for both scsi_run_queue_async() and blk-mq's
RESTART.

Fix the issue by not returning BLK_STS_DEV_RESOURCE in this situation.

Link: https://lore.kernel.org/r/20201202100419.525144-1-ming.lei@redhat.com
Fixes: 86ff7c2a80cd ("blk-mq: introduce BLK_STS_DEV_RESOURCE")
Cc: Hannes Reinecke <hare@...e.com>
Cc: Sumit Saxena <sumit.saxena@...adcom.com>
Cc: Kashyap Desai <kashyap.desai@...adcom.com>
Cc: Bart Van Assche <bvanassche@....org>
Cc: Ewan Milne <emilne@...hat.com>
Cc: Long Li <longli@...rosoft.com>
Reported-by: John Garry <john.garry@...wei.com>
Tested-by: "chenxiang (M)" <chenxiang66@...ilicon.com>
Signed-off-by: Ming Lei <ming.lei@...hat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Yu Kuai <yukuai3@...wei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/scsi/scsi_lib.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1719,8 +1719,7 @@ out_put_budget:
 	case BLK_STS_OK:
 		break;
 	case BLK_STS_RESOURCE:
-		if (atomic_read(&sdev->device_busy) ||
-		    scsi_device_blocked(sdev))
+		if (scsi_device_blocked(sdev))
 			ret = BLK_STS_DEV_RESOURCE;
 		break;
 	default: