Re: [PATCH 2/5] - fusion - target reset when drive is being removed

[James Smart <James.Smart@Emulex.Com>]

Yep - makes sense.

So, where I was driving to, Target Reset is a f/w command, not the actual
Task Management Function "Target Reset". No need to follow up..

Thanks.

-- james

Moore, Eric wrote:
> On Thursday, January 26, 2006 7:40 AM, James Smart wrote:
>> Interesting that you took this path.  I'm working on something similar
>> for the FC transport. When we finally decide the device is gone, we
>> want to kill the outstanding i/o. First thought in my mind was to use
>> a TMF - but this implies that you can contact the device to 
>> do the TMF.
>> Are you sending this before the device has actually gone away 
>> ?  If it's
>> after, I assume this then is a firmware function that handles things
>> accordingly at the link layer (e.g. may not send the TMF, 
>> will internally
>> abort the outstanding io's, may note the TR request and do it when the
>> device is later detected.... and so on).
>>
> 
> The target reset is issued from the device driver slave_destroy entry
> point.
> 
> This occurs after the device has been removed.   Meaning the driver
> receives a firmware event saying a device was deleted, then the driver
> calls the sas_transport layer to report the deleted device.  Then
> the scsi mid-layer calls the slave_destroy entry point, then the
> target reset is called.
> 
> This sole purpose is merely telling the firmware to complete the
> outstanding 
> commands back to the driver, so the mid-layer is getting all completed
> io
> for the device, thus preventing any future driver eh_threads from being
> called.
> 
> This was implemented in the LSI internal drivers some time ago, at that
> time
> when the driver received the "device delete" event, the device could
> still be
> getting io from above, and/or still have io pending in its queue.  The
> target
> reset will flush the queue, and thus return all the io's with abort'd
> status back
> to the driver.  That is why I had the target reset from the
> slave_destroy. 
> 
> Eric
>