linux-kernel - Re: [PATCH] Fix the x86 specializations of atomic_[set|clear]

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Message-ID: <20141016080209.GE7369@worktop.fdxtended.com>
Date:	Thu, 16 Oct 2014 10:02:09 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Patrick Palka <patrick@...cs.ath.cx>
Cc:	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Hans-Christian Egtvedt <egtvedt@...fundet.no>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	Pranith Kumar <bobby.prani@...il.com>
Subject: Re: [PATCH] Fix the x86 specializations of atomic_[set|clear]_mask

On Wed, Oct 15, 2014 at 04:38:01PM -0400, Patrick Palka wrote:
> This patch fixes a number of issues with these specializations:
> 
>   1. The memory operand inside the asm specification is erroneously
>   declared read-only instead of read-write.
> 
>   2. There is no reason to require the 1st operand of andl/orl to be
>   inside a register; the 1st operand could also be an immediate operand.
>   So change its specification from "r" to "ir".
> 
>   3. Since addr is supposed to be an atomic_t *, the memory operand
>   should be addr->counter and not *addr.
> 
>   4. These specializations should be inline functions instead of macros.
> 
>   5. Finally, the "memory" clobbers are unnecessary, so they should be
>   removed.  (This is in line with the other atomic functions such as
>   atomic_add and atomic_sub, the likes of which do not have a "memory"
>   clobber.)

No real problem with this, but I'm going to kill off these functions
when I get a little time :)
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