Re: [PATCH 4/6] Hexagon: check to if we will overflow the signalstack

From: Richard Kuo
Date: Thu Apr 04 2013 - 12:59:23 EST


On 04/04/2013 11:25 AM, Linas Vepstas wrote:
On 3 April 2013 19:02, Richard Kuo <rkuo@xxxxxxxxxxxxxx> 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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