Re: [PATCH 01/11] libiscsi: Convert to host_lock less w/ interrupts disabled internally

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

On 11/18/2010 03:59 AM, Boaz Harrosh wrote:
> On 11/18/2010 03:06 AM, Mike Christie wrote:
>> On 11/17/2010 04:18 PM, Nicholas A. Bellinger wrote:
>>>    prepd_fault:
>>>    	sc->scsi_done = NULL;
>>
>>> -	done(sc);
>>> -	spin_lock(host->host_lock);
>>> +	sc->scsi_done(sc);
>>>    	return 0;
>>
>> This will NULL pointer. See a couple lines above where we NULL it.
>> iscsi_free_task checks if the scsi_done pointer is set and if it is it
>> will call scsi_done.
>>
>> It is a hack to prevent the normal completion path from calling
>> scsi_done. For the case where we return SCSI_MLQUEUE_TARGET_BUSY (the
>> prepd_reject case) we need something to prevent scsi_done from getting
>> called.
>>
>> For the return 0/prepd_fault case we can just call sc->scsi_done, but we
>> have to move some code around.
>>
>> I do not like how the code does the NULLing and testing. Let me work on
>> this and send a tested patch.
>
> Mike if you are on this. Do you think we need the _irqsave locking.
> I always thought that the network receive is not on the HW interrupt
> but on a completion thread. Could you verify?
>

Yeah, we do not need the irqsave locking, because for software iscsi the 
session lock is just locked in softirqs/timers and the iscsi xmit 
thread. For offload and iser (be2iscsi, bnx2i, iser and cxgb*) we have 
similar combinations (some drivers have a tasklet thrown in there too) 
and no real interrupts.

qla4xxx does not use the iscsi_queuecommand function.