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

[Hannes Reinecke <hare@suse.de>]

On 02/12/2014 08:45 AM, Christoph Hellwig wrote:
> On Tue, Feb 11, 2014 at 03:29:10PM +0100, Hannes Reinecke wrote:
>> Well, _actually_ the cancel_delayed_work should be pointless; I've
>> just added it as a terminal measure here.
>> (It'd actually be an idea to insert a BUG_ON() here ...)
>>
>> Thing is whenever the eh_timeout thingie kicks in we most definitely
>> know there's a command in flight, and hence scsi_command_put()
>> should _never_ be called.
>> Only after eh_abort has finished the command will be returned via
>> scsi_command_put(), but then eh_abort is done for, too, and no item
>> should remain in the workqueue.
> 
> The issue I saw actually was with a different workqueue, sorry for the
> noise.  I have to say I really hate the generic workqueue workers which
> make it almost impossible to debug issues before they hit the actual
> worker function..
> 
Oh, workqueues are fun, no doubt.

_Especially_ when some poor deluded soul executes I/O from userspace
tasks running with RT priorities.

Handling that properly would be a fitting subject for LSF ...

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
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