[PATCH] nvme: fix hang in remove path

[Christoph Hellwig]

On Tue, Jun 06, 2017 at 10:10:45AM +0300, Sagi Grimberg wrote:
>
>>>> Note 7 here is NVME_SC_ABORT_REQ.  Also we would avoid walking through
>>>> all power states inside the nvme_configure_apst as
>>>> nvme_set_latency_tolerance was called with value
>>>> PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT (-1) which sets
>>>> ctrl->ps_max_latency_us to U64_MAX and tries to send a sync command
>>>> which of course fails with error message.
>>
>> Even though this change from this patch does fix the hang, just tested
>> again and I can see above error message "failed to set APST feature 7"
>> while nvme_remove PID is getting executed.
>>
>> So, sync requests (while nvme_remove is executing) are going through
>> and not everything is handled well in .queue_rq while controller is
>> under deleting state or dead state.
>
> The error message is expected because queue_rq is failing the I/O, did
> you see it actually hang?
>
> Personally I'm not too bothered with the error log, we can suppress it
> conditional on the ctrl state if it really annoys people, but if we're
> conditioning on the ctrl state, we can do it like you suggested anyway...

Yeah.  Or just remove the error printk entirely..