[PATCH v3 4/4] scsi: scsi_core: Fix IO hang when device removing

From: Wenchao Hao <haowenchao2@huawei.com>
To: "James E . J . Bottomley" <jejb@linux.ibm.com>,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	<linux-scsi@vger.kernel.org>
Cc: <linux-kernel@vger.kernel.org>, <louhongxiang@huawei.com>,
	Wenchao Hao <haowenchao2@huawei.com>
Subject: [PATCH v3 4/4] scsi: scsi_core: Fix IO hang when device removing
Date: Mon, 16 Oct 2023 10:03:14 +0800	[thread overview]
Message-ID: <20231016020314.1269636-5-haowenchao2@huawei.com> (raw)
In-Reply-To: <20231016020314.1269636-1-haowenchao2@huawei.com>

shost_for_each_device() would skip devices which is in progress of
removing, so scsi_run_queue() for these devices would be skipped in
scsi_run_host_queues() after blocking hosts' IO.

IO hang would be caused if return true when state is SDEV_CANCEL with
following order:

T1:					    T2:scsi_error_handler
__scsi_remove_device()
  scsi_device_set_state(sdev, SDEV_CANCEL)
  ...
  sd_remove()
  del_gendisk()
  blk_mq_freeze_queue_wait()
  					    scsi_eh_flush_done_q()
					      scsi_queue_insert(scmd,...)

scsi_queue_insert() would not kick device's queue since commit
8b566edbdbfb ("scsi: core: Only kick the requeue list if necessary")

After scsi_unjam_host(), the scsi error handler would call
scsi_run_host_queues() to trigger run queue for devices, while it
would not run queue for devices which is in progress of removing
because shost_for_each_device() would skip them.

So the requests added to these queues would not be handled any more,
and the removing device process would hang too.

Fix this issue by using shost_for_each_device_include_deleted() in
scsi_run_host_queues() to trigger a run queue for devices in removing.

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

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 195ca80667d0..40f407ffd26f 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -466,7 +466,7 @@ void scsi_run_host_queues(struct Scsi_Host *shost)
 {
 	struct scsi_device *sdev;
 
-	shost_for_each_device(sdev, shost)
+	shost_for_each_device_include_deleted(sdev, shost)
 		scsi_run_queue(sdev->request_queue);
 }
 
-- 
2.32.0

