[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] [PATCH 03/17] xen: arm32: ensure cmpxchg has full barrier semantics

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@xxxxxxxxxx>
> ---
> 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@xxxxxxxxxx>


Julien Grall

Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.