[PATCH 3.16 115/370] scsi: avoid a permanent stop of the scsi device's request queue

Ben Hutchings
2017-03-10T14:02:24Z

From: Wei Fang <fangwei1@huawei.com>

commit d2a145252c52792bc59e4767b486b26c430af4bb upstream.

A race between scanning and fc_remote_port_delete() may result in a
permanent stop if the device gets blocked before scsi_sysfs_add_sdev()
and unblocked after. The reason is that blocking a device sets both the
SDEV_BLOCKED state and the QUEUE_FLAG_STOPPED. However,
scsi_sysfs_add_sdev() unconditionally sets SDEV_RUNNING which causes the
device to be ignored by scsi_target_unblock() and thus never have its
QUEUE_FLAG_STOPPED cleared leading to a device which is apparently
running but has a stopped queue.

We actually have two places where SDEV_RUNNING is set: once in
scsi_add_lun() which respects the blocked flag and once in
scsi_sysfs_add_sdev() which doesn't. Since the second set is entirely
spurious, simply remove it to fix the problem.

Reported-by: Zengxi Chen <chenzengxi@huawei.com>
Signed-off-by: Wei Fang <fangwei1@huawei.com>
Reviewed-by: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/scsi/scsi_sysfs.c | 4 ----
1 file changed, 4 deletions(-)

--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -1002,10 +1002,6 @@ int scsi_sysfs_add_sdev(struct scsi_devi
struct request_queue *rq = sdev->request_queue;
struct scsi_target *starget = sdev->sdev_target;

- error = scsi_device_set_state(sdev, SDEV_RUNNING);
- if (error)
- return error;
-
error = scsi_target_add(starget);
if (error)
return error;