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From: Segher Boessenkool <segher@kernel.crashing.org>
Subject: Re: alpha: half done futex implementation
Date: Tue, 14 Apr 2009 11:40:50 +0200
To: Richard Henderson <rth@twiddle.net>
Cc: Oliver Falk <oliver@linux-kernel.at>, linux-kernel@vger.kernel.org,
	linuxppc-dev@ozlabs.org, Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
	linux-alpha@vger.kernel.org, Matt Turner <mattst88@gmail.com>,
	Jay Estabrook <jay.estabrook@hp.com>
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> Also, there's a bug in the powerpc implementation.  It appears that  
> oparg is clobbered, and if stwcx fails the operation will be  
> repeated with incorrect inputs.

If either the lwarx or the stwcx. faults, the routine returns -EFAULT
and doesn't retry (label "3" is the end of the asm).

If the stwcx. fails because the CPU lost the reservation, %1 isn't
clobbered as far as I see?


Segher