Re: [RFC 3/3] kernel.h: use new typechecking macros in min()/max()and friends
From: Linus Torvalds
Date: Sat Apr 14 2012 - 17:18:11 EST
On Sat, Apr 14, 2012 at 3:14 PM, Sasha Levin <levinsasha928@xxxxxxxxx> wrote:
> Convert to using new typechecking macros in kernel.h. This prevents code
> duplication and makes the modified macros (easily) readable again.
>
> #define min(x, y) ({ \
> - typeof(x) _min1 = (x); \
> - typeof(y) _min2 = (y); \
> - (void) (&_min1 == &_min2); \
> - _min1 < _min2 ? _min1 : _min2; })
> + typecmp2((x), (y)); \
> + (x) < (y) ? (x) : (y); })
They may be readable, but they are total shit.
You now evaluate 'x' and 'y' multiple times, so if they are function
calls or contain other side effects (like "a++" etc), you get the
wrong result.
So no. Hell no.
Linus
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