Re: [PATCH 2/5] scsi: improved eh timeout handler

[Hannes Reinecke <hare@suse.de>]

On 11/06/2013 06:23 PM, Mike Christie wrote:
> On 11/05/2013 10:48 PM, Hannes Reinecke wrote:
>> On 11/05/2013 08:19 PM, Mike Christie wrote:
>>> On 11/04/2013 11:05 PM, Hannes Reinecke wrote:
>>>> +
>>>> +	scmd->eh_eflags |= SCSI_EH_ABORT_SCHEDULED;
>>>> +	SCSI_LOG_ERROR_RECOVERY(3,
>>>> +		scmd_printk(KERN_INFO, scmd,
>>>> +			    "scmd %p abort scheduled\n", scmd));
>>>> +	schedule_delayed_work(&scmd->abort_work, HZ / 100);
>>>> +	return SUCCESS;
>>>> +}
>>>
>>> Do we want to use our own workqueue_struct with WQ_MEM_RECLAIM set?
>>>
>> Errm. Yes, why?
>>
>> I must admit I'm not _that_ familiar with workqueues ...
>> Care to explain?
>>
> 
> We all share the above workqueue_structs pool of threads, so if we get
> stuck behind code doing GFP_KERNEL allocs that end up needing to write
> data to the disk we are now trying to aborts on, then we could get
> stuck. With WQ_MEM_RECLAIM, we have our own backup thread that gets
> created at workqueue_struct create time which can get used in cases like
> that so we can always make forward progress.
> 
Ah. Right. Yes, that makes sense.

I guess I'll have to redo the patches _yet again_.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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