linux-kernel - Re: [PATCH tip/core/rcu 1/4] mce: Stop using array-index-based RCU primitives

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Message-ID: <20150513103157.GF1517@pd.tnic>
Date:	Wed, 13 May 2015 12:31:57 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc:	linux-kernel@...r.kernel.org, mingo@...nel.org,
	laijs@...fujitsu.com, dipankar@...ibm.com,
	akpm@...ux-foundation.org, mathieu.desnoyers@...icios.com,
	josh@...htriplett.org, tglx@...utronix.de, peterz@...radead.org,
	rostedt@...dmis.org, dhowells@...hat.com, edumazet@...gle.com,
	dvhart@...ux.intel.com, fweisbec@...il.com, oleg@...hat.com,
	bobby.prani@...il.com, linux-edac@...r.kernel.org,
	Tony Luck <tony.luck@...el.com>
Subject: Re: [PATCH tip/core/rcu 1/4] mce: Stop using array-index-based RCU
 primitives

On Tue, May 12, 2015 at 02:18:41PM -0700, Paul E. McKenney wrote:
> From: "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
> 
> Because mce is arch-specific x86 code, there is little or no
> performance benefit of using rcu_dereference_index_check() over using
> smp_load_acquire().  It also turns out that mce is the only place that
> array-index-based RCU is used, and it would be convenient to drop
> this portion of the RCU API.
> 
> This patch therefore changes rcu_dereference_index_check() uses to
> smp_load_acquire(), but keeping the lockdep diagnostics, and also
> changes rcu_access_index() uses to READ_ONCE().
> 
> Signed-off-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com>
> Cc: linux-edac@...r.kernel.org
> Cc: Tony Luck <tony.luck@...el.com>
> Cc: Borislav Petkov <bp@...en8.de>

Looks good to me.

If it is easier for you carrying it in your tree:

Acked-by: Borislav Petkov <bp@...e.de>

Otherwise, let me know.

Thanks.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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