From: Julien Grall <julien.grall@linaro.org>
To: Ian Campbell <ian.campbell@citrix.com>
Cc: stefano.stabellini@eu.citrix.com, tim@xen.org, xen-devel@lists.xen.org
Subject: Re: [PATCH 03/17] xen: arm32: ensure cmpxchg has full barrier semantics
Date: Thu, 20 Mar 2014 17:22:20 +0000 [thread overview]
Message-ID: <532B23CC.4090204@linaro.org> (raw)
In-Reply-To: <1395330365-9901-3-git-send-email-ian.campbell@citrix.com>
Hi Ian,
On 03/20/2014 03:45 PM, Ian Campbell wrote:
> Unrelated reads/writes should not pass the xchg.
>
> Provide cmpxchg_local for parity with arm64, although it appears to be unused.
> It also helps make the reason for the separation of __cmpxchg_mb more
> apparent.
>
> With this our cmpxchg is in sync with Linux v3.14-rc7.
>
> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> ---
> We got our cmpxchg implementation from Linux which AFAICS has always had these
> additional barriers. I don't recall us having decided that Xen barriers should
> not have this property as well, and if we did we were remiss in not adding a
> comment etc... If my memory is faulty then I am happy to replace thispatch
> with one which adds a comment instead.
I think the barrier is good for Xen. We may have some place where both
of this macro are used as a "barrier".
Acked-by: Julien Grall <julien.grall@linaro.org>
Regards,
--
Julien Grall
next prev parent reply other threads:[~2014-03-20 17:22 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-20 15:45 [PATCH 00/17] xen: arm: resync low level asm primitive from Linux Ian Campbell
2014-03-20 15:45 ` [PATCH 01/17] xen: x86 & generic: change to __builtin_prefetch() Ian Campbell
2014-03-20 16:12 ` Jan Beulich
2014-03-20 15:45 ` [PATCH 02/17] xen: arm32: resync bitops with Linux v3.14-rc7 Ian Campbell
2014-03-20 17:13 ` Julien Grall
2014-03-20 15:45 ` [PATCH 03/17] xen: arm32: ensure cmpxchg has full barrier semantics Ian Campbell
2014-03-20 17:22 ` Julien Grall [this message]
2014-03-20 15:45 ` [PATCH 04/17] xen: arm32: replace hard tabs in atomics.h Ian Campbell
2014-03-20 17:23 ` Julien Grall
2014-03-20 15:45 ` [PATCH 05/17] xen: arm32: resync atomics with (almost) v3.14-rc7 Ian Campbell
2014-03-20 17:27 ` Julien Grall
2014-03-21 8:41 ` Ian Campbell
2014-03-20 15:45 ` [PATCH 06/17] xen: arm32: resync mem* with Linux v3.14-rc7 Ian Campbell
2014-03-20 17:29 ` Julien Grall
2014-03-20 15:45 ` [PATCH 07/17] xen: arm32: add optimised memchr routine Ian Campbell
2014-03-20 17:32 ` Julien Grall
2014-03-20 15:45 ` [PATCH 08/17] xen: arm32: add optimised strchr and strrchr routines Ian Campbell
2014-03-20 17:33 ` Julien Grall
2014-03-20 15:45 ` [PATCH 09/17] xen: arm: remove atomic_clear_mask() Ian Campbell
2014-03-20 17:35 ` Julien Grall
2014-03-20 15:45 ` [PATCH 10/17] xen: arm64: disable alignment traps Ian Campbell
2014-03-20 15:57 ` Andrew Cooper
2014-03-20 15:59 ` Ian Campbell
2014-03-20 16:21 ` Gordan Bobic
2014-03-20 16:27 ` Ian Campbell
2014-03-20 16:43 ` Gordan Bobic
2014-03-20 16:54 ` Ian Campbell
2014-03-20 17:54 ` Julien Grall
2014-03-20 15:45 ` [PATCH 11/17] xen: arm64: atomics: fix use of acquire + release for full barrier semantics Ian Campbell
2014-03-20 17:43 ` Julien Grall
2014-03-20 15:46 ` [PATCH 12/17] xen: arm64: reinstate hard tabs in system.h cmpxchg Ian Campbell
2014-03-20 17:44 ` Julien Grall
2014-03-20 15:46 ` [PATCH 13/17] xen: arm64: asm: remove redundant "cc" clobbers Ian Campbell
2014-03-20 17:45 ` Julien Grall
2014-03-20 15:46 ` [PATCH 14/17] xen: arm64: assembly optimised mem* and str* Ian Campbell
2014-03-20 17:48 ` Julien Grall
2014-03-20 15:46 ` [PATCH 15/17] xen: arm64: optimised clear_page Ian Campbell
2014-03-20 15:46 ` [PATCH 16/17] xen: arm: refactor xchg and cmpxchg into their own headers Ian Campbell
2014-03-20 17:52 ` Julien Grall
2014-03-21 8:42 ` Ian Campbell
2014-03-20 15:46 ` [PATCH 17/17] xen: arm: document what low level primitives we have imported from Linux Ian Campbell
2014-03-20 16:23 ` Ian Campbell
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