Re: [PATCH 00/18] x86: Ticket lock + cmpxchg cleanup

[Linus Torvalds]

On Wed, Aug 24, 2011 at 4:09 PM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> However, the reason I disagree with it is that I don't think that it's
> any prettier at all to have the two barriers than it is to just have
> the asm.

.. and btw, we probably do need *both* barriers. We definitely need
the one before. The one after is a bit less obvious, since it is
technically legal for code to move into the locked region. However,
it's not necessarily a *good* idea for code to move into the locked
region, so the two barriers are likely the RightThing(tm). But the two
barriers are what makes me think that the C version really isn't any
better. And the OOSTORE case then just clinches the deal for me.

                         Linus
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