Re: [PATCH] scsi: avoid a permanent stop of the scsi device's request queue

[Wei Fang <fangwei1@huawei.com>]

Hi, Bart,

On 2016/12/6 23:51, Bart Van Assche wrote:
> On 12/06/16 01:12, Wei Fang wrote:
>> The scsi device is being setted to the SDEV_RUNNING state at the end of
>> the scan work. When the remote port reappears, scsi_target_unblock()
>> will be called, but the QUEUE_FLAG_STOPPED flag will not be cleared,
>> since scsi_internal_device_unblock() ignores SCSI devices in SDEV_RUNNING
>> state. It results in a permanent stop of the scsi device's request
>> queue. Every requests sended to it will be blocked.
> 
> Hello Wei,
> 
> scsi_device_set_state() does not allow the transition from 
> SDEV_CREATED_BLOCK to SDEV_RUNNING. If a SCSI device is blocked after it 
> has been added to the __devices list and before scsi_add_lun() finishes 
> then I think the scan code will change its state into SDEV_BLOCK. Are 
> you sure what you described above is what happened?

Yes, we already encountered this case on out machine:

The state of the scsi device first is changed to SDEV_BLOCK in
scsi_add_lun() as you metioned, then it will be changed to SDEV_RUNNING
in scsi_sysfs_add_sdev().

Thanks,
Wei