linux-kernel - [PATCH 2/2] scsi: core: decrease scsi_device's iorequest

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Date:   Mon, 15 May 2023 15:01:56 +0800
From:   Wenchao Hao <haowenchao2@...wei.com>
To:     "James E . J . Bottomley" <jejb@...ux.ibm.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        Ming Lei <ming.lei@...hat.com>, <linux-scsi@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC:     <linfeilong@...wei.com>, <louhongxiang@...wei.com>,
        Wenchao Hao <haowenchao2@...wei.com>
Subject: [PATCH 2/2] scsi: core: decrease scsi_device's iorequest_cnt if dispatch failed

If scsi_dispatch_cmd() failed, the SCSI command was not sent to the target,
scsi_queue_rq() would return BLK_STS_RESOURCE and the related request
would be requeued. The timeout of this request would not fire, no one would
increase iodone_cnt.

The above flow would result the iodone_cnt smaller than iorequest_cnt.
So decrease the iorequest_cnt if dispatch failed to workaround the issue.

Link:https://lore.kernel.org/linux-scsi/8e0f2d31-e6ff-ec4a-3974-450560ad49c5@huawei.com/T/#t

Signed-off-by: Wenchao Hao <haowenchao2@...wei.com>
---
 drivers/scsi/scsi_lib.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 03964b26f3f2..0226c9279cef 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1485,6 +1485,7 @@ static int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
 		 */
 		SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
 			"queuecommand : device blocked\n"));
+		atomic_dec(&cmd->device->iorequest_cnt);
 		return SCSI_MLQUEUE_DEVICE_BUSY;
 	}
 
@@ -1517,6 +1518,7 @@ static int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
 	trace_scsi_dispatch_cmd_start(cmd);
 	rtn = host->hostt->queuecommand(host, cmd);
 	if (rtn) {
+		atomic_dec(&cmd->device->iorequest_cnt);
 		trace_scsi_dispatch_cmd_error(cmd, rtn);
 		if (rtn != SCSI_MLQUEUE_DEVICE_BUSY &&
 		    rtn != SCSI_MLQUEUE_TARGET_BUSY)
-- 
2.32.0