Re: Debugging scsi abort handling ?

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 08/29/2014 12:30 PM, Hannes Reinecke wrote:
> On 08/29/2014 12:14 PM, Finn Thain wrote:
>>
>> On Fri, 29 Aug 2014, Hannes Reinecke wrote:
>>
>>> On 08/29/2014 06:39 AM, Finn Thain wrote:
>>>>
>>>> On Thu, 28 Aug 2014, Hannes Reinecke wrote:
>>>>
>>>>> What might happen, though, that the command is already dead and gone
>>>>> by the time you're calling ->scsi_done() (if you call it after
>>>>> eh_abort). So there might not _be_ a command upon which you can call
>>>>> ->scsi_done() to start with.
>>>>>
>>>>> Hence any LLDD need to clear up any internal references after a call
>>>>> to eh_XXX to ensure it doesn't call ->scsi_done() an in invalid
>>>>> command.
>>>>>
>>>>> So even if the LLDD returns 'FAILED' upon a call to eh_XXX it
>>>>> _still_ needs to clear up the internal reference.
>>>>
>>>> This is a question that has been bothering me too. If the host's
>>>> eh_abort_cmd() method returns FAILED, it seems the mid-layer is liable
>>>> to re-issue the same command to the LLD (?)
>>>>
>>> No.
>>> FAILED for any eh_abort_cmd() means that the TMF hasn't been sent.
>>
>> Makes sense, though it appears to contradict this advice about returning
>> SUCCESS in some situations:
>> http://marc.info/?l=linux-scsi&m=140923498632496&w=2
>>
> Well, if the LLDD detects an invalid command (ie if it cannot find any internal command matching the midlayer command) that's an automatic success, obviously.
> 
> So we should rephrase things to:
> 
> - The eh_XXX callback shall return 'SUCCESS' if the respective
>   TMF (or equvalent) could be initiated or if the matching command
>   reference has already been completed by the LLDD. Otherwise
>   the eh_XXX callback shall return 'FAILED'.

Your talking about "could be initiated", so that means that at this
point the abort does not yet have to be completed, do I get that
right? What should the LLDD then do when the abort finishes,
call eh_scsi_done on the cmnd ?

What about the abort never finishing (timeout), does the mid layer
track this, or should the LLDD do that?

Regards,

Hans