linux-kernel - Re: [PATCH 4/6] Hexagon: check to if we will overflow the signal stack

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Date:	Thu, 04 Apr 2013 11:58:58 -0500
From:	Richard Kuo <rkuo@...eaurora.org>
To:	linasvepstas@...il.com
CC:	linux-arch@...r.kernel.org, linux-hexagon@...r.kernel.org,
	linux-kernel@...r.kernel.org, viro@...iv.linux.org.uk
Subject: Re: [PATCH 4/6] Hexagon: check to if we will overflow the signal
 stack

On 04/04/2013 11:25 AM, Linas Vepstas wrote:
> On 3 April 2013 19:02, Richard Kuo <rkuo@...eaurora.org> wrote:
>
>> +       /* check if we would overflow the alt stack */
>> +       if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
>> +               return (void __user __force *)-1UL;
> I found the !likely construction confusing, as its doing both a
> 'unlikely' (right?) and inverting the argument. It seems clearer,
> to idiots like me, to write this as:
>
> if (on_sig_stack(sp) && unlikely(!on_sig_stack(sp - frame_size)))
>
> since where checking for overflow, and its unlikely that the overflow happened.
>
> -- Linas

I'm not sure if putting a double negative in there will make it less not 
easy to understand...


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