linux-kernel - Re: [PATCH RFC] riscv/barrier: Define __smp

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Message-ID: <20180226103552.GA9138@andrea>
Date:   Mon, 26 Feb 2018 11:35:52 +0100
From:   Andrea Parri <parri.andrea@...il.com>
To:     Palmer Dabbelt <palmer@...ive.com>
Cc:     albert@...ive.com, linux-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] riscv/barrier: Define __smp_{mb,rmb,wmb}

On Thu, Feb 22, 2018 at 03:14:52PM -0800, Palmer Dabbelt wrote:
> On Tue, 20 Feb 2018 02:17:28 PST (-0800), parri.andrea@...il.com wrote:
> >Introduce __smp_{mb,rmb,wmb}, and rely on the generic definitions
> >for smp_{mb,rmb,wmb}. A first consequence is that smp_{mb,rmb,wmb}
> >map to a compiler barrier on !SMP (while their definition remains
> >unchanged on SMP). As a further consequence, smp_load_acquire and
> >smp_store_release have "fence rw,rw" instead of "fence iorw,iorw".
> >
> >Signed-off-by: Andrea Parri <parri.andrea@...il.com>
> >---
> > arch/riscv/include/asm/barrier.h | 6 +++---
> > 1 file changed, 3 insertions(+), 3 deletions(-)
> >
> >diff --git a/arch/riscv/include/asm/barrier.h b/arch/riscv/include/asm/barrier.h
> >index c0319cbf1eec5..5510366d169ae 100644
> >--- a/arch/riscv/include/asm/barrier.h
> >+++ b/arch/riscv/include/asm/barrier.h
> >@@ -34,9 +34,9 @@
> > #define wmb()		RISCV_FENCE(ow,ow)
> >
> > /* These barriers do not need to enforce ordering on devices, just memory. */
> >-#define smp_mb()	RISCV_FENCE(rw,rw)
> >-#define smp_rmb()	RISCV_FENCE(r,r)
> >-#define smp_wmb()	RISCV_FENCE(w,w)
> >+#define __smp_mb()	RISCV_FENCE(rw,rw)
> >+#define __smp_rmb()	RISCV_FENCE(r,r)
> >+#define __smp_wmb()	RISCV_FENCE(w,w)
> >
> > /*
> >  * This is a very specific barrier: it's currently only used in two places in
> 
> Thanks!  I'm going to take this for the next RC.

Thank you, Palmer.  I'm planning to post more changes to the file,
but I'd like to build on top of this change: could you point me to
the appropriate branch/repo for this?

  Andrea