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

[Hannes Reinecke <hare@suse.de>]

On 11/09/2013 09:35 AM, James Bottomley wrote:
> On Thu, 2013-11-07 at 07:45 +0100, Hannes Reinecke wrote:
>> 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_.
>
> So when were you going to send the redo?  The merge window is now open
> and Linus was shirty with me about a late merge last time ...
>
Patch is prepared, I'll just have to run a verification on it.
Will be sending the updated patchset on Monday.

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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