linux-kernel - Re: 2.6.30: hald crashes on resume from STR apparently on LED device

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Message-Id: <200906280034.51738.arvidjaar@mail.ru>
Date:	Sun, 28 Jun 2009 00:34:48 +0400
From:	Andrey Borzenkov <arvidjaar@...l.ru>
To:	Richard Purdie <rpurdie@...ys.net>
Cc:	hal@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: 2.6.30: hald crashes on resume from STR apparently on LED device

On Monday 22 of June 2009 17:57:24 Richard Purdie wrote:
> On Sun, 2009-06-21 at 18:17 +0400, Andrey Borzenkov wrote:
> > So what happens is simple. During suspend led device is removed;
> > during resume it is recreated. Apparently removing led device cause
> > hald-addon- leds to exit (thus disconnecting D-Bus connection); and
> > sometimes next "add" event comes too early, before hald had chance
> > to notice missing addon.
>
> Note that its the underlying device that is being removed here and
> since the LED is connected to that its removed as well. The LED
> subsystem hasn't changed in how it works. I don't think that has any
> bearing on your patch though.
>

Yes, looking more closely there is inherent race condition between 
tearing down existing helper and processing ADD event for it. Most 
likely some timing was changed in current kernel that made it more 
easily exposed. If Mandriva had not compiled D-Bus with assertions 
enabled, this would simply fail silently without anyone noticing.

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