linux-kernel - Re: [PATCH] ieee1394: nodemgr: fix deadlock in shutdown

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Message-ID: <4564AE86.2020905@s5r6.in-berlin.de>
Date:	Wed, 22 Nov 2006 21:09:42 +0100
From:	Stefan Richter <stefanr@...6.in-berlin.de>
To:	Alan Stern <stern@...land.harvard.edu>
CC:	linux1394-devel@...ts.sourceforge.net,
	Greg Kroah-Hartman <gregkh@...e.de>,
	linux-kernel@...r.kernel.org, Dmitry Torokhov <dtor@...ightbb.com>
Subject: Re: [PATCH] ieee1394: nodemgr: fix deadlock in shutdown

Alan Stern wrote:
> On Tue, 21 Nov 2006, Stefan Richter wrote:
>> There is now a /sys/bus/ieee1394/drivers/ieee1394,

(I'll rename it to nodemgr when I commit this patch.)

>> whose "bind" and "unbind" attributes are not welcome.  Is there a way
>> to disable them?
> 
> You can always prevent "bind" from operating by returning an error code
> from the driver's probe routine (although it's not clear why you would
> want to do that).  I don't think there's any way to make the "unbind"
> attribute stop working.
> 
> You could violate the layering and remove the attribute files directly.  
> But that would be a race; there would remain a brief interval between the 
> time the files were created and the time you removed them.

Does this matter if there is no device which can be unbound?

Anyway, I don't think I will go this route unless a real problem with
the attributes turns up.

> Lastly, you could remove source of your deadlock by having the unbind 
> routine for the new driver delete all the child device structures.

Hmm, I won't believe you until I actually try it. :-)

> In fact, just to make things more symmetric and logical you could have 
> the probe routine create those child devices in the first place!

Sounds good. It's on my .plan now.
-- 
Stefan Richter
-=====-=-==- =-== =-==-
http://arcgraph.de/sr/
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