Re: [PATCH 07/15] x86: add xadd helper macro

From: H. Peter Anvin
Date: Mon Aug 22 2011 - 19:30:17 EST


On 08/22/2011 04:15 PM, Jeremy Fitzhardinge wrote:
> From: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
>
> Add a common xadd implementation.
>
> This has the side effect of generating a bad instruction if you try to
> use it on a 64-bit value on a 32-bit system - but don't do that.
>

It would be better to barf at that point, so we get the error with a C
line... also, there needs to be a default clause with
__compiletime_error() in it.

There are a few additional xadd users which should be converted unless
I'm mistaken:

rwsem_atomic_update() in asm/rwsem.h.

atomic_add_return() in asm/atomic.h.

atomic64_add_return() in asm/atomic64_64.h.

atom_asr() in asm/uv/uv_bau.h (*VOMIT* - the UV people have created a
whole different type in private code...)

-hpa
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