On 2023/9/22 17:36, Wenchao Hao wrote:
SDEV_CANCEL is set when removing device and scsi_device_online() should
return false if sdev_state is SDEV_CANCEL.
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)
scsi_eh_flush_done_q()
if (scsi_device_online(sdev))
scsi_queue_insert(scmd,...)
The command added by scsi_queue_insert() would never be handled any
more.
Signed-off-by: Wenchao Hao <haowenchao2@xxxxxxxxxx>
---
include/scsi/scsi_device.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index 75b2235b99e2..c498a12f7715 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -517,7 +517,8 @@ static inline int scsi_device_online(struct scsi_device *sdev)
{
return (sdev->sdev_state != SDEV_OFFLINE &&
sdev->sdev_state != SDEV_TRANSPORT_OFFLINE &&
- sdev->sdev_state != SDEV_DEL);
+ sdev->sdev_state != SDEV_DEL &&
+ sdev->sdev_state != SDEV_CANCEL);
}
static inline int scsi_device_blocked(struct scsi_device *sdev)
{
Return false when if sdev_state is SDEV_CANCEL seems change some flow in
error handle, but I don't know if we should introduce these changes.
I think it's both ok to finish the failed command or try more recovery steps.
For example, in scsi_eh_bus_device_reset(), when scsi_try_bus_device_reset()
returned SUCCEED but the sdev_state is SDEV_CANCEL, should skip TUR and just
call scsi_eh_finish_cmd() to add this LUN's error command to done_q?
We can address the issue of IO hang described in this patch by running
scsi_device's queue regardless of the scsi_device's state and it seems
a better solution because the main reason of IO hang is as following:
scsi_restart_operations()
-> scsi_run_host_queues()
-> shost_for_each_device() // skip scsi_device with SDEV_DEL
// or SDEV_CANCEL state
