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

[James Bottomley <jbottomley@parallels.com>]

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 ...

James