Re: [PATCH v2 04/15] IB/srp: Fail I/O fast if target offline

[Sebastian Riemer <sebastian.riemer-EIkl63zCoXaH+58JC4qpiA@public.gmane.org>]

On 01.07.2013 13:38, Bart Van Assche wrote:
>>> --- a/drivers/infiniband/ulp/srp/ib_srp.c
>>> +++ b/drivers/infiniband/ulp/srp/ib_srp.c
>>> @@ -1755,6 +1755,8 @@ static int srp_abort(struct scsi_cmnd *scmnd)
>>>       if (srp_send_tsk_mgmt(target, req->index, scmnd->device->lun,
>>>                     SRP_TSK_ABORT_TASK) == 0)
>>>           ret = SUCCESS;
>>> +    else if (target->transport_offline)
>>> +        ret = FAST_IO_FAIL;
>>>       else
>>>           ret = FAILED;
>>>       srp_free_req(target, req, scmnd, 0);
>>
>> I'm also missing the concept for srp_reset_device(). There is a very
>> common case that the SCSI error handling and the transport layer error
>> handling run in parallel: Congestion.
> 
> Can you explain this comment further, and also how this comment relates
> to patch 04/15 ?

Sorry, found it. Even if only one srp_reset_device() fails, then
srp_reset_host() is called anyway. So there this check + returning
FAST_IO_FAIL doesn't make so much sense.

>> In congestion some LUNs are blocked while others can still transmit. A
>> little bit later the QP timeout triggers in the middle of the SCSI error
>> handling in srp_abort(), srp_reset_device() or less likely in
>> srp_reset_host().
> 
> I am aware this can result in concurrent srp_reconnect_rport() calls.
> However, such concurrent calls are serialized via rport->mutex.

I put my comment regarding this to patch 10.

Cheers,
Sebastian
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