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Commit 79d44246 authored by Andrea Parri's avatar Andrea Parri Committed by Ingo Molnar
Browse files

locking/xchg/alpha: Clean up barrier usage by using smp_mb() in place of __ASM__MB 



Replace each occurrence of __ASM__MB with a (trailing) smp_mb() in
xchg(), cmpxchg(), and remove the now unused __ASM__MB definitions;
this improves readability, with no additional synchronization cost.

Suggested-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarAndrea Parri <parri.andrea@gmail.com>
Acked-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-alpha@vger.kernel.org
Link: http://lkml.kernel.org/r/1519291469-5702-1-git-send-email-parri.andrea@gmail.com


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent cb13b424

arch/alpha/include/asm/cmpxchg.h

+0 −6
Original line number Diff line number Diff line
@@ -6,7 +6,6 @@ 
 * Atomic exchange routines.

 */



#define __ASM__MB

#define ____xchg(type, args...)		__xchg ## type ## _local(args)

#define ____cmpxchg(type, args...)	__cmpxchg ## type ## _local(args)

#include <asm/xchg.h>
@@ -33,10 +32,6 @@ 
	cmpxchg_local((ptr), (o), (n));					\

})



#ifdef CONFIG_SMP

#undef __ASM__MB

#define __ASM__MB	"\tmb\n"

#endif

#undef ____xchg

#undef ____cmpxchg

#define ____xchg(type, args...)		__xchg ##type(args)
@@ -64,7 +59,6 @@ 
	cmpxchg((ptr), (o), (n));					\

})



#undef __ASM__MB

#undef ____cmpxchg



#endif /* _ALPHA_CMPXCHG_H */

arch/alpha/include/asm/xchg.h

+8 −8
Original line number Diff line number Diff line
@@ -28,12 +28,12 @@ ____xchg(_u8, volatile char *m, unsigned long val) 
	"	or	%1,%2,%2\n"

	"	stq_c	%2,0(%3)\n"

	"	beq	%2,2f\n"

		__ASM__MB

	".subsection 2\n"

	"2:	br	1b\n"

	".previous"

	: "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64)

	: "r" ((long)m), "1" (val) : "memory");

	smp_mb();



	return ret;

}
@@ -52,12 +52,12 @@ ____xchg(_u16, volatile short *m, unsigned long val) 
	"	or	%1,%2,%2\n"

	"	stq_c	%2,0(%3)\n"

	"	beq	%2,2f\n"

		__ASM__MB

	".subsection 2\n"

	"2:	br	1b\n"

	".previous"

	: "=&r" (ret), "=&r" (val), "=&r" (tmp), "=&r" (addr64)

	: "r" ((long)m), "1" (val) : "memory");

	smp_mb();



	return ret;

}
@@ -72,12 +72,12 @@ ____xchg(_u32, volatile int *m, unsigned long val) 
	"	bis $31,%3,%1\n"

	"	stl_c %1,%2\n"

	"	beq %1,2f\n"

		__ASM__MB

	".subsection 2\n"

	"2:	br 1b\n"

	".previous"

	: "=&r" (val), "=&r" (dummy), "=m" (*m)

	: "rI" (val), "m" (*m) : "memory");

	smp_mb();



	return val;

}
@@ -92,12 +92,12 @@ ____xchg(_u64, volatile long *m, unsigned long val) 
	"	bis $31,%3,%1\n"

	"	stq_c %1,%2\n"

	"	beq %1,2f\n"

		__ASM__MB

	".subsection 2\n"

	"2:	br 1b\n"

	".previous"

	: "=&r" (val), "=&r" (dummy), "=m" (*m)

	: "rI" (val), "m" (*m) : "memory");

	smp_mb();



	return val;

}
@@ -150,12 +150,12 @@ ____cmpxchg(_u8, volatile char *m, unsigned char old, unsigned char new) 
	"	stq_c	%2,0(%4)\n"

	"	beq	%2,3f\n"

	"2:\n"

		__ASM__MB

	".subsection 2\n"

	"3:	br	1b\n"

	".previous"

	: "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64)

	: "r" ((long)m), "Ir" (old), "1" (new) : "memory");

	smp_mb();



	return prev;

}
@@ -177,12 +177,12 @@ ____cmpxchg(_u16, volatile short *m, unsigned short old, unsigned short new) 
	"	stq_c	%2,0(%4)\n"

	"	beq	%2,3f\n"

	"2:\n"

		__ASM__MB

	".subsection 2\n"

	"3:	br	1b\n"

	".previous"

	: "=&r" (prev), "=&r" (new), "=&r" (tmp), "=&r" (cmp), "=&r" (addr64)

	: "r" ((long)m), "Ir" (old), "1" (new) : "memory");

	smp_mb();



	return prev;

}
@@ -200,12 +200,12 @@ ____cmpxchg(_u32, volatile int *m, int old, int new) 
	"	stl_c %1,%2\n"

	"	beq %1,3f\n"

	"2:\n"

		__ASM__MB

	".subsection 2\n"

	"3:	br 1b\n"

	".previous"

	: "=&r"(prev), "=&r"(cmp), "=m"(*m)

	: "r"((long) old), "r"(new), "m"(*m) : "memory");

	smp_mb();



	return prev;

}
@@ -223,12 +223,12 @@ ____cmpxchg(_u64, volatile long *m, unsigned long old, unsigned long new) 
	"	stq_c %1,%2\n"

	"	beq %1,3f\n"

	"2:\n"

		__ASM__MB

	".subsection 2\n"

	"3:	br 1b\n"

	".previous"

	: "=&r"(prev), "=&r"(cmp), "=m"(*m)

	: "r"((long) old), "r"(new), "m"(*m) : "memory");

	smp_mb();



	return prev;

}