Device is not becoming offline on failed TUR

Device is not becoming offline on failed TUR

[Lev Vainblat]

Hello,

We have a virtual target that under some circumstances returns 
HARDWARE_ERROR (4/44) on TUR. Previously on initiator side 
scsi_check_sense() returned TARGET_ERROR, that in scsi_eh_tur() was 
converted to 1 (device not ready). And then scsi_eh_ready_devs() called 
scsi_eh_offline_sdevs to move device to the OFFLINE state.

In commit 
http://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=87f14e6 
this logic has been changed. Now on HARDWARE_ERROR scsi_check_sense() only 
sets DID_TARGET_FAILURE and returns SUCCESS. As a result device remains 
"running", and scsi_eh_flush_done_q() doesn't finish the command but retries 
it. So in this case it takes for the stuck command much more time to finish.

Am I missing something? Is it a bug or intentional new behavior?

Thanks,
    Lev. 

Re: Device is not becoming offline on failed TUR

[Hannes Reinecke]

On 01/17/2016 11:54 AM, Lev Vainblat wrote:
> Hello,
> 
> We have a virtual target that under some circumstances returns
> HARDWARE_ERROR (4/44) on TUR. Previously on initiator side
> scsi_check_sense() returned TARGET_ERROR, that in scsi_eh_tur() was
> converted to 1 (device not ready). And then scsi_eh_ready_devs()
> called scsi_eh_offline_sdevs to move device to the OFFLINE state.
> 
> In commit
> http://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=87f14e6
> this logic has been changed. Now on HARDWARE_ERROR
> scsi_check_sense() only sets DID_TARGET_FAILURE and returns SUCCESS.
> As a result device remains "running", and scsi_eh_flush_done_q()
> doesn't finish the command but retries it. So in this case it takes
> for the stuck command much more time to finish.
> 
> Am I missing something? Is it a bug or intentional new behavior?
> 
That is intentional.
We should only ever set the device to 'offline' is we cannot
communicate with it.
If we can (and that is the case here, as the drive returns a sense
code) the communication is okay, and the device should not be set to
offline.

It's up to the driver/calling application to correctly handle the
sense code.
As usual.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
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SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
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