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

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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@xxxxxxx			      +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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