Re: [PATCH 3/4] scsi: improved eh timeout handler

[Hannes Reinecke <hare@suse.de>]

On 06/10/2013 02:12 AM, Baruch Even wrote:
> On Thu, Jun 6, 2013 at 12:43 PM, Hannes Reinecke <hare@suse.de> wrote:
>> When a command runs into a timeout we need to send an 'ABORT TASK'
>> TMF. This is typically done by the 'eh_abort_handler' LLDD callback.
>>
>> Conceptually, however, this function is a normal SCSI command, so
>> there is no need to enter the error handler.
>>
>> This patch implements a new scsi_abort_command() function which
>> invokes an asynchronous function scsi_eh_abort_handler() to
>> abort the commands via 'eh_abort_handler'.
>>
>> If the 'eh_abort_handler' returns SUCCESS or FAST_IO_FAIL the
>> command will be retried if possible. If no retries are allowed
>> the command will be returned immediately, as we have to assume
>> the TMF succeeded and the command is completed with the LLDD.
>> For any other return code from 'eh_abort_handler' the command
>> will be pushed onto the existing SCSI EH handler, or aborted
>> with DID_TIME_OUT if that fails.
>>
> 
> Why would you do a retry at this low level? We already have a bad path,
> the IO may already be rerouted through another path and continuing with this
> IO here may interfere with the multipath handling.
> 
For multipathing no retries would be set, so the command would
be returned immediately.

I checked.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
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