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Date: Tue, 25 May 2010 20:37:40 +0200 (CEST)
From: Thomas Gleixner <tglx@linutronix.de>
To: Linus Torvalds <torvalds@linux-foundation.org>
cc: Jeff Chua <jeff.chua.linux@gmail.com>,
       Johannes Berg <johannes.berg@intel.com>,
       Arjan van de Ven <arjan@linux.intel.com>,
       "johnstul@us.ibm.com" <johnstul@us.ibm.com>,
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       Intel Linux Wireless <ilw@linux.intel.com>,
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       Frans Pop <elendil@planet.nl>,
       "Chatre, Reinette" <reinette.chatre@intel.com>,
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Subject: Re: Wireless IBSS on Linux-2.6.34 broken by commit
 3bbb9ec946428b96657126768f65487a48dd090c
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On Mon, 24 May 2010, Linus Torvalds wrote:
> 
> On Mon, 24 May 2010, Jeff Chua wrote:
> > 
> > -	expires_limit = expires + timer->slack;
> > +	expires_limit = expires;
> > 
> > -	if (timer->slack < 0) /* auto slack: use 0.4% */
> > +	if (timer->slack > -1)
> > +		expires_limit = expires + timer->slack;
> > +	else if (time_after(expires, jiffies)) /* auto slack: use 0.4% */
> >  		expires_limit = expires + (expires - jiffies)/256;
> 
> Please don't reload 'jiffies' twice. It's volatile, and the compiler will 
> do a crap job of it. 

Grr, it's even worse. If jiffies increment between the time_after()
check and (expires - jiffies) we might run into the same problem as
before. Sigh, did not notice when I picked it up. ENOTENOUGHCOFFEE.
 
> Also, '0' is a normal number, but '-1' is a rather odd value. Please just 
> test for non-negative by doing ">= 0" rather than "> -1"

Will fix, thanks,

     tglx