Commit c38425df authored by Guo Ren's avatar Guo Ren
Browse files

csky: Fixup asm/cmpxchg.h with correct ordering barrier 



Optimize the performance of cmpxchg by using more fine-grained
acquire/release barriers.

Signed-off-by: default avatarGuo Ren <guoren@linux.alibaba.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Paul E. McKenney <paulmck@kernel.org>
parent d6c5cb9f

arch/csky/include/asm/cmpxchg.h

+17 −10
Original line number Diff line number Diff line
@@ -3,12 +3,12 @@ 
#ifndef __ASM_CSKY_CMPXCHG_H

#define __ASM_CSKY_CMPXCHG_H



#ifdef CONFIG_CPU_HAS_LDSTEX

#ifdef CONFIG_SMP

#include <asm/barrier.h>



extern void __bad_xchg(void);



#define __xchg(new, ptr, size)					\

#define __xchg_relaxed(new, ptr, size)				\

({								\

	__typeof__(ptr) __ptr = (ptr);				\

	__typeof__(new) __new = (new);				\
@@ -16,7 +16,6 @@ extern void __bad_xchg(void); 
	unsigned long tmp;					\

	switch (size) {						\

	case 4:							\

		smp_mb();					\

		asm volatile (					\

		"1:	ldex.w		%0, (%3) \n"		\

		"	mov		%1, %2   \n"		\
@@ -25,7 +24,6 @@ extern void __bad_xchg(void); 
			: "=&r" (__ret), "=&r" (tmp)		\

			: "r" (__new), "r"(__ptr)		\

			:);					\

		smp_mb();					\

		break;						\

	default:						\

		__bad_xchg();					\
@@ -33,9 +31,10 @@ extern void __bad_xchg(void); 
	__ret;							\

})



#define xchg(ptr, x)	(__xchg((x), (ptr), sizeof(*(ptr))))

#define xchg_relaxed(ptr, x) \

		(__xchg_relaxed((x), (ptr), sizeof(*(ptr))))



#define __cmpxchg(ptr, old, new, size)				\

#define __cmpxchg_relaxed(ptr, old, new, size)			\

({								\

	__typeof__(ptr) __ptr = (ptr);				\

	__typeof__(new) __new = (new);				\
@@ -44,7 +43,6 @@ extern void __bad_xchg(void); 
	__typeof__(*(ptr)) __ret;				\

	switch (size) {						\

	case 4:							\

		smp_mb();					\

		asm volatile (					\

		"1:	ldex.w		%0, (%3) \n"		\

		"	cmpne		%0, %4   \n"		\
@@ -56,7 +54,6 @@ extern void __bad_xchg(void); 
			: "=&r" (__ret), "=&r" (__tmp)		\

			: "r" (__new), "r"(__ptr), "r"(__old)	\

			:);					\

		smp_mb();					\

		break;						\

	default:						\

		__bad_xchg();					\
@@ -64,8 +61,18 @@ extern void __bad_xchg(void); 
	__ret;							\

})



#define cmpxchg_relaxed(ptr, o, n) \

	(__cmpxchg_relaxed((ptr), (o), (n), sizeof(*(ptr))))



#define cmpxchg(ptr, o, n) 					\

	(__cmpxchg((ptr), (o), (n), sizeof(*(ptr))))

({								\

	__typeof__(*(ptr)) __ret;				\

	__smp_release_fence();					\

	__ret = cmpxchg_relaxed(ptr, o, n);			\

	__smp_acquire_fence();					\

	__ret;							\

})



#else

#include <asm-generic/cmpxchg.h>

#endif