Re: [RESEND, tip/locking/core, v5, 1/6] powerpc: atomic: Make _return atomics and *{cmp}xchg fully ordered

From: Boqun Feng
Date: Mon Oct 26 2015 - 23:07:25 EST

On Tue, Oct 27, 2015 at 01:33:47PM +1100, Michael Ellerman wrote:
> On Mon, 2015-26-10 at 10:15:36 UTC, Boqun Feng wrote:
> > This patch fixes two problems to make value-returning atomics and
> > {cmp}xchg fully ordered on PPC.
> Hi Boqun,
> Can you please split this into two patches. One that does the cmpxchg change
> and one that changes PPC_ATOMIC_ENTRY_BARRIER.

OK, make sense ;-)

> Also given how pervasive this change is I'd like to take it via the powerpc
> next tree, so can you please send this patch (which will be two after you split
> it) as powerpc patches. And the rest can go via tip?

One problem is that patch 5 will remove __xchg_u32 and __xchg_64
entirely, which are modified in this patch(patch 1), so there will be
some conflicts if two branch get merged, I think.

Alternative way is that all this series go to powerpc next tree as most
of the dependent patches are already there. I just need to remove
inc/dec related code and resend them when appropriate. Besides, I can
pull patch 2 out and send it as a tip patch because it's general code
and no one depends on this in this series.

To summerize:

patch 1(split to two), 3, 4(remove inc/dec implementation), 5, 6 sent as
powerpc patches for powerpc next, patch 2(unmodified) sent as tip patch
for locking/core.

Peter and Michael, this works for you both?


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