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From: Peter Zijlstra <peterz@infradead.org>
To: stern@rowland.harvard.edu, akiyks@gmail.com,
	andrea.parri@amarulasolutions.com, boqun.feng@gmail.com,
	dlustig@nvidia.com, dhowells@redhat.com, j.alglave@ucl.ac.uk,
	luc.maranget@inria.fr, npiggin@gmail.com, paulmck@linux.ibm.com,
	peterz@infradead.org, will.deacon@arm.com
Cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
	Huacai Chen <chenhc@lemote.com>, Huang Pei <huangpei@loongson.cn>,
	Paul Burton <paul.burton@mips.com>
Subject: [RFC][PATCH 3/5] mips/atomic: Optimize loongson3_llsc_mb()
Date: Wed, 24 Apr 2019 14:36:59 +0200
Message-ID: <20190424124421.693353463@infradead.org> (raw)
In-Reply-To: <20190424123656.484227701@infradead.org>

Now that every single LL/SC loop has loongson_llsc_mb() in front, we
can NO-OP smp_mb__before_llsc() in that case.

While there, remove the superfluous __smp_mb__before_llsc().

Cc: Huacai Chen <chenhc@lemote.com>
Cc: Huang Pei <huangpei@loongson.cn>
Cc: Paul Burton <paul.burton@mips.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/mips/include/asm/barrier.h |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

--- a/arch/mips/include/asm/barrier.h
+++ b/arch/mips/include/asm/barrier.h
@@ -221,15 +221,12 @@
 
 #ifdef CONFIG_CPU_CAVIUM_OCTEON
 #define smp_mb__before_llsc() smp_wmb()
-#define __smp_mb__before_llsc() __smp_wmb()
 /* Cause previous writes to become visible on all CPUs as soon as possible */
 #define nudge_writes() __asm__ __volatile__(".set push\n\t"		\
 					    ".set arch=octeon\n\t"	\
 					    "syncw\n\t"			\
 					    ".set pop" : : : "memory")
 #else
-#define smp_mb__before_llsc() smp_llsc_mb()
-#define __smp_mb__before_llsc() smp_llsc_mb()
 #define nudge_writes() mb()
 #endif
 
@@ -264,11 +261,19 @@
  *    This case affects all current Loongson 3 CPUs.
  */
 #ifdef CONFIG_CPU_LOONGSON3_WORKAROUNDS /* Loongson-3's LLSC workaround */
+#define smp_mb__before_llsc()	do { } while (0)
 #define loongson_llsc_mb()	__asm__ __volatile__("sync" : : :"memory")
 #else
 #define loongson_llsc_mb()	do { } while (0)
 #endif
 
+#ifndef smp_mb__before_llsc
+#define smp_mb__before_llsc() smp_llsc_mb()
+#endif
+
+#define __smp_mb__before_atomic()	smp_mb__before_llsc()
+#define __smp_mb__after_atomic()	smp_llsc_mb()
+
 static inline void sync_ginv(void)
 {
 	asm volatile("sync\t%0" :: "i"(STYPE_GINV));



  parent reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-24 12:36 [RFC][PATCH 0/5] atomic: Fixes to smp_mb__{before,after}_atomic() and mips Peter Zijlstra
2019-04-24 12:36 ` [RFC][PATCH 1/5] mips/atomic: Fix cmpxchg64 barriers Peter Zijlstra
2019-04-24 21:00   ` Paul Burton
2019-04-25  6:59     ` Peter Zijlstra
2019-04-24 12:36 ` [RFC][PATCH 2/5] mips/atomic: Fix loongson_llsc_mb() wreckage Peter Zijlstra
2019-04-24 12:59   ` Peter Zijlstra
2019-04-24 21:18   ` Paul Burton
2019-04-25  4:58     ` huangpei
2019-04-25  7:33       ` Peter Zijlstra
2019-04-25  9:09         ` Peter Zijlstra
2019-04-25 12:14           ` huangpei
2019-04-25  9:12         ` Peter Zijlstra
2019-05-14 15:58           ` Peter Zijlstra
2019-05-14 16:10             ` Linus Torvalds
2019-05-14 16:56               ` Peter Zijlstra
2019-05-14 17:07                 ` Linus Torvalds
2019-05-15 13:50               ` huangpei
2019-04-25 11:32         ` huangpei
2019-04-25 12:26           ` Peter Zijlstra
2019-04-25 12:51             ` huangpei
2019-04-25 13:31               ` Peter Zijlstra
2019-04-26  2:57                 ` huangpei
2019-05-14 15:46                   ` Peter Zijlstra
2019-04-25 16:12       ` Linus Torvalds
2019-04-25  7:15     ` Peter Zijlstra
2019-04-24 12:36 ` Peter Zijlstra [this message]
2019-04-24 12:37 ` [RFC][PATCH 4/5] mips/atomic: Fix smp_mb__{before,after}_atomic() Peter Zijlstra
2019-04-24 21:24   ` Paul Burton
2019-04-25  7:34     ` Peter Zijlstra
2019-04-24 12:37 ` [RFC][PATCH 5/5] x86/atomic: " Peter Zijlstra
2019-04-24 13:41   ` Will Deacon

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