linux-kernel - Re: [gcv v3 27/35] arm: Replace __get_cpu

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Message-ID: <20130828195415.GP6617@n2100.arm.linux.org.uk>
Date:	Wed, 28 Aug 2013 20:54:15 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Christoph Lameter <cl@...ux.com>
Cc:	Tejun Heo <tj@...nel.org>, akpm@...uxfoundation.org,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>, linux-arch@...r.kernel.org,
	Steven Rostedt <srostedt@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [gcv v3 27/35] arm: Replace __get_cpu_var uses

On Wed, Aug 28, 2013 at 07:48:23PM +0000, Christoph Lameter wrote:
> 3. Retrieve the content of the current processors instance of a per cpu variable.
> 
> 	DEFINE_PER_CPU(int, u);

Shouldn't this be 'y' ?

> 	int x = __get_cpu_var(y)
> 
>    Converts to
> 
> 	int x = __this_cpu_read(y);
> 
> 
> 4. Retrieve the content of a percpu struct
> 
> 	DEFINE_PER_CPU(struct mystruct, y);
> 	struct mystruct x = __get_cpu_var(y);
> 
>    Converts to
> 
> 	memcpy(this_cpu_ptr(&x), y, sizeof(x));

Are you sure this one's correct?  Isn't 'y' the per-cpu variable?
Even though I don't see any in this patch, it's probably a good thing to
get the patch description correct.

I think you need Will Deacon's ack for this, but I think he's away for
a while.
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