2023-09-28 07:50:07

by Wenchao Hao

[permalink] [raw]
Subject: [PATCH v2 4/4] scsi: scsi_core: Fix IO hang when device removing

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,...)

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

After scsi_unjam_host(), the scsi error handler would call scsi_run_queue()
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_queue() to trigger a run queue for devices in removing.

Signed-off-by: Wenchao Hao <[email protected]>
---
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 c2f647a7c1b0..34b408d182e2 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