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Date: Thu, 12 Oct 2017 19:43:37 -0500
From: Segher Boessenkool <segher@kernel.crashing.org>
To: Santosh Sivaraj <santosh@fossix.org>
Cc: linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
 "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
 Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
 John Stultz <john.stultz@linaro.org>, Thomas Gleixner <tglx@linutronix.de>,
 Frederic Weisbecker <fweisbec@gmail.com>, paul@samba.org
Subject: Re: [PATCH v5] powerpc/vdso64: Add support for
 CLOCK_{REALTIME/MONOTONIC}_COARSE
Message-ID: <20171013004336.GV4406@gate.crashing.org>
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 <20171011170216.GR4406@gate.crashing.org>
 <20171012043317.xtfhwpf4dmnvu3bj@santosiv.in.ibm.com>
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Hi!

On Thu, Oct 12, 2017 at 10:03:17AM +0530, Santosh Sivaraj wrote:
> * Segher Boessenkool <segher@kernel.crashing.org> wrote (on 2017-10-11 17:02:16 +0000):
> > On Wed, Oct 11, 2017 at 02:05:02PM +0530, Santosh Sivaraj wrote:
> > > +70:	ld      r8,CFG_TB_UPDATE_COUNT(r3)
> > > +	andi.   r0,r8,1                 /* pending update ? loop */
> > > +	bne-    70b
> > > +	xor     r0,r8,r8                /* create dependency */
> > 
> > r0 already is 0 here, and already depends on r8.  Or is this trying
> > to do something else?
> 
> The function from which this piece was borrowed from had a similar
> implementation, didn't figure out why the extra dependency, kept it the way it
> was. See __do_get_tspec function in the same file
> (arch/powerpc/kernel/vdso64/gettimeofday.S).

The xor there is superfluous, too.


Segher