[PATCHv3 9/9] nvme-pci: Don't wait for HMB completion on shutdown

[jianchao.w.wang@oracle.com (jianchao.wang)]

Hi Keith

On 05/25/2018 05:15 AM, Keith Busch wrote:
>> Also if we really need to reset the controller submitting any command
>> just doesn't seem very helpful.  We might as well just skip trying
>> to disable the HMB, as the controller needs to come up in a clean
>> state anyway.
> That's also fine with me.
> 

Does it mean just need to disable the controller with transiting CC.EN ?1? to ?0?
without sending any admin commands including deleting cq/sq ?
The specification indeed says that
when Controller Reset (CC.EN transitions from ?1? to ?0
 - The controller stops processing any outstanding Admin or I/O commands.
 - All I/O Submission Queues are deleted.
 - All I/O Completion Queues are deleted.
 - The controller is brought to an Idle state. When this is complete, CSTS.RDY is cleared to ?0?.
 - The Admin Queue registers (AQA, ASQ, or ACQ) are not reset as part of a controller reset. All
other controller registers defined in section 3 and internal controller state are reset.

Then for the timeout case at least, for LIVE state, nvme_timeout could hand over all the things to
reset_work and return BLK_EH_RESET_TIMER, when reset_work is ongoing, just  disable the controller
with setting CC.EN and disable the related pci things and return BLK_EH_HANDLED to complete the
admin commands to wake up the reset_work. (certainly with your patch to move update_hw_nr to scan_work)
nvme_timeout doesn't need to invoke nvme_dev_disable any more and life will be simpler :).

Thanks
jianchao