Re: [Open-FCoE] [v2 PATCH 4/5] bnx2fc: Broadcom FCoE Offload driver submission - part 2

[Mike Christie <michaelc@cs.wisc.edu>]

On 02/02/2011 10:05 PM, Mike Christie wrote:
> On 02/02/2011 09:42 PM, Bhanu Gollapudi wrote:
>>>
>>> Actually you do not have to wait for the scsi eh to run, right. It
>>> looks
>>> like bnx2fc would log out the port, which ends up calling
>>> fc_remote_port_delete and that would cause the fc timed out function
>>> to
>>> return BLK_EH_RESET_TIMER to prevent the scsi eh from running. Is
>>> that
>>> right? That type of eh strategy behavior seems like something you
>>> want
>>> to sync up with libfc or the fc class so all drivers do something
>>> similar.
>>
>> As per FCP-4, if the ABTS times out, we will have to explicitly LOGO the
>
> What section is that in?
>

Ok read it (12.5.1, right).

>> target and relogin back. If we rely on 60 sec eh_abort_handler, and if
>> ABTS times out, SCSI error handling will go to LUN RESET, TGT reset
>> path, which is a generic error handling than transport specific error
>> handling.
>
> If that is right, then it seems the other FC drivers are doing it wrong
> then, and you hit that problem if someone sets the scsi cmd timer lower
> than BNX2FC_IO_TIMEOUT. If that is right, that just does not seem right
> to hack around the issue in the driver too.

So if your reading of 12.5.1 is right then libfc is wrong and it seems 
other drivers (if they are not doing some magic in firmware) are wrong too.

My confidence in my FCP skills are very shaken right now :) I am not 
sure I what I was thinking when I read it and reviewed libfc. I think 
you need to discuss this out the fcoe list people and James Smart and 
Andrew Vasquez.

I think some of them disagree with the other aborting commands (or maybe 
just disagree about some of the details), so that should be discussed too.

But if you are right then you cannot work around this in a driver 
specific way. You need to change libfc and the fc class in a way that 
the error strategy is correct. For example from fc_timed_out you could 
kick off the abort. I was slightly off on the other comment about libfc 
not doing a abort from their internal timeout handler. They do an abort 
still, but if that fails they let the scsi eh run eventually. I thought 
they were going to clean that up too when they removed their internal 
timer value in the "libfc: use rport timeout values for fcp recovery" patch.