Re: [PATCH] Protect prefetch macro arguments.

From: Linus Torvalds
Date: Fri Mar 26 2010 - 17:09:14 EST




On Fri, 26 Mar 2010, David Daney wrote:
>
> The GCC built-in __builtin_prefetch() is a vargs function. If we
> don't wrap the macro parameter in parentheses, a comma operator in the
> actual argument list might cause unintended parameters to be passed to
> __builtin_prefetch().

This seems totally pointless and actively wrong.

You cannot have a comma operator in the actual argument list to the
#define, because if you did, then you'd get a

macro "prefetch()" passed 2 arguments, but takes just 1

so the only way I see to pass a comma operator is to _already_ have the
macro parameter in parenthesis.

Linus
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