From: "H. Peter Anvin" <hpa@zytor.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@elte.hu>,
the arch/x86 maintainers <x86@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Nick Piggin <npiggin@kernel.dk>,
Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Subject: Re: [PATCH 07/15] x86: add xadd helper macro
Date: Mon, 22 Aug 2011 21:41:09 -0700 [thread overview]
Message-ID: <4E532F65.7010609@zytor.com> (raw)
In-Reply-To: <4E52E9BF.3050904@goop.org>
On 08/22/2011 04:43 PM, Jeremy Fitzhardinge wrote:
> On 08/22/2011 04:29 PM, H. Peter Anvin wrote:
>> On 08/22/2011 04:15 PM, Jeremy Fitzhardinge wrote:
>>> From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
>>>
>>> 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.
>
> OK, but the "standard of care" here is the old "calling undefined
> function" link error; getting a bad asm instruction is a little more
> helpful, in a sense. But agreed on the default: case. I'll see if I
> can fix up xadd and cmpxchg to fail better as well.
>
__compiletime_error() is better than either, obviously...
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
next prev parent reply other threads:[~2011-08-23 4:42 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-22 23:14 [PATCH 00/12] x86: Ticket lock cleanup Jeremy Fitzhardinge
[not found] ` <cover.1314054734.git.jeremy.fitzhardinge@citrix.com>
2011-08-22 23:14 ` [PATCH 01/15] x86/ticketlock: clean up types and accessors Jeremy Fitzhardinge
2011-08-22 23:14 ` [PATCH 02/15] x86/ticketlock: convert spin loop to C Jeremy Fitzhardinge
2011-08-22 23:14 ` [PATCH 03/15] x86/ticketlock: Use C for __ticket_spin_unlock Jeremy Fitzhardinge
2011-08-22 23:15 ` [PATCH 04/15] x86/ticketlock: make large and small ticket versions of spin_lock the same Jeremy Fitzhardinge
2011-08-22 23:15 ` [PATCH 05/15] x86/ticketlock: make __ticket_spin_lock common Jeremy Fitzhardinge
2011-08-22 23:15 ` [PATCH 06/15] x86/ticketlock: make __ticket_spin_trylock common Jeremy Fitzhardinge
2011-08-22 23:15 ` [PATCH 07/15] x86: add xadd helper macro Jeremy Fitzhardinge
2011-08-22 23:29 ` H. Peter Anvin
2011-08-22 23:43 ` Jeremy Fitzhardinge
2011-08-23 4:41 ` H. Peter Anvin [this message]
2011-08-23 10:59 ` Peter Zijlstra
2011-08-23 16:34 ` Jeremy Fitzhardinge
2011-08-22 23:15 ` [PATCH 08/15] x86/ticketlock: use xadd helper Jeremy Fitzhardinge
2011-08-22 23:15 ` [PATCH 09/15] x86/cmpxchg: linux/alternative.h has LOCK_PREFIX Jeremy Fitzhardinge
2011-08-22 23:15 ` [PATCH 10/15] x86/cmpxchg: move 32-bit __cmpxchg_wrong_size to match 64 bit Jeremy Fitzhardinge
2011-08-22 23:15 ` [PATCH 11/15] x86/cmpxchg: move 64-bit set64_bit() to match 32-bit Jeremy Fitzhardinge
2011-08-22 23:15 ` [PATCH 12/15] x86/cmpxchg: unify cmpxchg into cmpxchg.h Jeremy Fitzhardinge
2011-08-22 23:15 ` [PATCH 13/15] x86: add cmpxchg_flag() variant Jeremy Fitzhardinge
2011-08-23 19:01 ` Christoph Lameter
2011-08-23 19:22 ` H. Peter Anvin
2011-08-23 19:52 ` Christoph Lameter
2011-08-23 21:03 ` H. Peter Anvin
2011-08-23 19:53 ` Jeremy Fitzhardinge
2011-08-23 20:45 ` H. Peter Anvin
2011-08-23 22:15 ` Jeremy Fitzhardinge
2011-08-23 22:43 ` H. Peter Anvin
2011-08-24 13:54 ` Christoph Lameter
2011-08-24 13:53 ` Christoph Lameter
2011-08-24 16:33 ` Jeremy Fitzhardinge
2011-08-24 19:27 ` Christoph Lameter
2011-08-24 20:15 ` Jeremy Fitzhardinge
2011-08-24 20:31 ` H. Peter Anvin
2011-08-24 20:38 ` Jeremy Fitzhardinge
2011-08-24 23:04 ` H. Peter Anvin
2011-08-24 23:11 ` Linus Torvalds
2011-08-24 23:19 ` Jeremy Fitzhardinge
2011-08-25 14:07 ` Christoph Lameter
2011-08-22 23:15 ` [PATCH 14/15] x86/ticketlocks: use cmpxchg_flag for trylock Jeremy Fitzhardinge
2011-08-22 23:15 ` [PATCH 15/15] x86: use cmpxchg_flag() where applicable Jeremy Fitzhardinge
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