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Message-ID: <20131107111741.GD13139@mudshark.cambridge.arm.com>
Date: Thu, 7 Nov 2013 11:17:41 +0000
From: Will Deacon <will.deacon@....com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Geert Uytterhoeven <geert@...ux-m68k.org>,
"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Victor Kaplansky <VICTORK@...ibm.com>,
Oleg Nesterov <oleg@...hat.com>,
Anton Blanchard <anton@...ba.org>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Frederic Weisbecker <fweisbec@...il.com>,
LKML <linux-kernel@...r.kernel.org>,
Linux PPC dev <linuxppc-dev@...abs.org>,
Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
Michael Ellerman <michael@...erman.id.au>,
Michael Neuling <mikey@...ling.org>,
Russell King <linux@....linux.org.uk>,
Martin Schwidefsky <schwidefsky@...ibm.com>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Tony Luck <tony.luck@...el.com>
Subject: Re: [RFC] arch: Introduce new TSO memory barrier smp_tmb()
Hi Peter,
Couple of minor fixes on the arm64 side...
On Wed, Nov 06, 2013 at 01:57:36PM +0000, Peter Zijlstra wrote:
> --- a/arch/arm64/include/asm/barrier.h
> +++ b/arch/arm64/include/asm/barrier.h
> @@ -35,11 +35,59 @@
> #define smp_mb() barrier()
> #define smp_rmb() barrier()
> #define smp_wmb() barrier()
> +
> +#define smp_store_release(p, v) \
> +do { \
> + compiletime_assert_atomic_type(*p); \
> + smp_mb(); \
> + ACCESS_ONCE(*p) = (v); \
> +} while (0)
> +
> +#define smp_load_acquire(p) \
> +({ \
> + typeof(*p) ___p1 = ACCESS_ONCE(*p); \
> + compiletime_assert_atomic_type(*p); \
> + smp_mb(); \
> + ___p1; \
> +})
> +
> #else
> +
> #define smp_mb() asm volatile("dmb ish" : : : "memory")
> #define smp_rmb() asm volatile("dmb ishld" : : : "memory")
> #define smp_wmb() asm volatile("dmb ishst" : : : "memory")
> -#endif
Why are you getting rid of this #endif?
> +#define smp_store_release(p, v) \
> +do { \
> + compiletime_assert_atomic_type(*p); \
> + switch (sizeof(*p)) { \
> + case 4: \
> + asm volatile ("stlr %w1, [%0]" \
> + : "=Q" (*p) : "r" (v) : "memory"); \
> + break; \
> + case 8: \
> + asm volatile ("stlr %1, [%0]" \
> + : "=Q" (*p) : "r" (v) : "memory"); \
> + break; \
> + } \
> +} while (0)
> +
> +#define smp_load_acquire(p) \
> +({ \
> + typeof(*p) ___p1; \
> + compiletime_assert_atomic_type(*p); \
> + switch (sizeof(*p)) { \
> + case 4: \
> + asm volatile ("ldar %w0, [%1]" \
> + : "=r" (___p1) : "Q" (*p) : "memory"); \
> + break; \
> + case 8: \
> + asm volatile ("ldar %0, [%1]" \
> + : "=r" (___p1) : "Q" (*p) : "memory"); \
> + break; \
> + } \
> + ___p1; \
> +})
You don't need the square brackets when using the "Q" constraint (otherwise
it will expand to something like [[x0]], which gas won't accept).
With those changes, for the general idea and arm/arm64 parts:
Acked-by: Will Deacon <will.deacon@....com>
Will
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