linux-kernel - Re: [PATCH] time: Add locking to xtime access in get

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Date:	Thu, 5 May 2011 19:57:13 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	john stultz <johnstul@...ibm.com>
Cc:	Andi Kleen <andi@...stfloor.org>,
	lkml <linux-kernel@...r.kernel.org>,
	Paul Mackerras <paulus@...ba.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Anton Blanchard <anton@...ba.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH] time: Add locking to xtime access in get_seconds()

> I suspect the reason this hasn't been triggered on x86 or power6 is due
> to compiler or processor optimizations reordering the assignment to in
> effect make it atomic. Or maybe the timing window to see the issue is
> harder to observe?

On x86 all aligned stores are atomic. So I don't see how this 
could be a problem ever.

Are you saying that on P6 only atomic stores are atomic?

If that's the case again I suspect other code will be affected
too.

-Andi
> 
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