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

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Message-ID: <20130905130359.GA22351@mudshark.cambridge.arm.com>
Date:	Thu, 5 Sep 2013 14:03:59 +0100
From:	Will Deacon <will.deacon@....com>
To:	Christoph Lameter <cl@...ux.com>
Cc:	Tejun Heo <tj@...nel.org>,
	"akpm@...uxfoundation.org" <akpm@...uxfoundation.org>,
	Russell King <linux@....linux.org.uk>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
	Steven Rostedt <srostedt@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [gcv v3 27/35] arm: Replace __get_cpu_var uses

Hi again Christoph,

On Wed, Sep 04, 2013 at 09:58:31PM +0100, Christoph Lameter wrote:
> Here is a patch to be applied after the earlier one to convert the local_t
> use to this_cpu. Not sure if I got the local_dec_and_test conversion
> right.

[...]

> @@ -118,11 +117,11 @@ void disable_debug_monitors(enum debug_e
> 
>  	WARN_ON(preemptible());
> 
> -	if (local_dec_and_test(this_cpu_ptr(&mde_ref_count)))
> +	if (this_cpu_dec_return(mde_ref_count))
>  		disable = ~DBG_MDSCR_MDE;
> 
>  	if (el == DBG_ACTIVE_EL1 &&
> -	    local_dec_and_test(this_cpu_ptr(&kde_ref_count)))
> +	    this_cpu_dec_return(kde_ref_count))
>  		disable &= ~DBG_MDSCR_KDE;

Almost! I think we just need an '== 0' check on the result from the
decrement, since local_dec_and_test is simply a way to check that we've
decremented to zero, so this patch would otherwise invert the meaning.

Will
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