Commit 8578bdf8 authored by Andi Kleen's avatar Andi Kleen Committed by Andi Kleen
Browse files

[PATCH] Don't use lock section for mutexes and semaphores 



Lock sections cannot be handled by the dwarf2 unwinder.

Disadvantage is a taken branch in the hot path.

Signed-off-by: default avatarAndi Kleen <ak@suse.de>
parent 7ca2b49b

include/asm-x86_64/mutex.h

+6 −14
Original line number Diff line number Diff line
@@ -25,13 +25,9 @@ do { \ 
									\

	__asm__ __volatile__(						\

		LOCK_PREFIX "   decl (%%rdi)	\n"			\

			"   js 2f		\n"			\

			"1:			\n"			\

									\

		LOCK_SECTION_START("")					\

			"2: call "#fail_fn"	\n"			\

			"   jmp 1b		\n"			\

		LOCK_SECTION_END					\

			"   jns 1f		\n"			\

			"   call "#fail_fn"	\n"			\

			"1:"						\

									\

		:"=D" (dummy)						\

		: "D" (v)						\
@@ -75,13 +71,9 @@ do { \ 
									\

	__asm__ __volatile__(						\

		LOCK_PREFIX "   incl (%%rdi)	\n"			\

			"   jle 2f		\n"			\

			"1:			\n"			\

									\

		LOCK_SECTION_START("")					\

			"2: call "#fail_fn"	\n"			\

			"   jmp 1b		\n"			\

		LOCK_SECTION_END					\

			"   jg 1f		\n"			\

			"   call "#fail_fn"	\n"			\

			"1:			  "			\

									\

		:"=D" (dummy)						\

		: "D" (v)						\

include/asm-x86_64/semaphore.h

+14 −26
Original line number Diff line number Diff line
@@ -107,12 +107,9 @@ static inline void down(struct semaphore * sem) 
	__asm__ __volatile__(

		"# atomic down operation\n\t"

		LOCK_PREFIX "decl %0\n\t"     /* --sem->count */

		"js 2f\n"

		"1:\n"

		LOCK_SECTION_START("")

		"2:\tcall __down_failed\n\t"

		"jmp 1b\n"

		LOCK_SECTION_END

		"jns 1f\n\t"

		"call __down_failed\n"

		"1:"

		:"=m" (sem->count)

		:"D" (sem)

		:"memory");
@@ -130,14 +127,11 @@ static inline int down_interruptible(struct semaphore * sem) 


	__asm__ __volatile__(

		"# atomic interruptible down operation\n\t"

		"xorl %0,%0\n\t"

		LOCK_PREFIX "decl %1\n\t"     /* --sem->count */

		"js 2f\n\t"

		"xorl %0,%0\n"

		"1:\n"

		LOCK_SECTION_START("")

		"2:\tcall __down_failed_interruptible\n\t"

		"jmp 1b\n"

		LOCK_SECTION_END

		"jns 2f\n\t"

		"call __down_failed_interruptible\n"

		"2:\n"

		:"=a" (result), "=m" (sem->count)

		:"D" (sem)

		:"memory");
@@ -154,14 +148,11 @@ static inline int down_trylock(struct semaphore * sem) 


	__asm__ __volatile__(

		"# atomic interruptible down operation\n\t"

		"xorl %0,%0\n\t"

		LOCK_PREFIX "decl %1\n\t"     /* --sem->count */

		"js 2f\n\t"

		"xorl %0,%0\n"

		"1:\n"

		LOCK_SECTION_START("")

		"2:\tcall __down_failed_trylock\n\t"

		"jmp 1b\n"

		LOCK_SECTION_END

		"jns 2f\n\t"

		"call __down_failed_trylock\n\t"

		"2:\n"

		:"=a" (result), "=m" (sem->count)

		:"D" (sem)

		:"memory","cc");
@@ -179,12 +170,9 @@ static inline void up(struct semaphore * sem) 
	__asm__ __volatile__(

		"# atomic up operation\n\t"

		LOCK_PREFIX "incl %0\n\t"     /* ++sem->count */

		"jle 2f\n"

		"1:\n"

		LOCK_SECTION_START("")

		"2:\tcall __up_wakeup\n\t"

		"jmp 1b\n"

		LOCK_SECTION_END

		"jg 1f\n\t"

		"call __up_wakeup\n"

		"1:"

		:"=m" (sem->count)

		:"D" (sem)

		:"memory");

include/asm-x86_64/spinlock.h

+4 −5
Original line number Diff line number Diff line
@@ -22,14 +22,13 @@ 
#define __raw_spin_lock_string \

	"\n1:\t" \

	LOCK_PREFIX " ; decl %0\n\t" \

	"js 2f\n" \

	LOCK_SECTION_START("") \

	"2:\t" \

	"jns 2f\n" \

	"3:\n" \

	"rep;nop\n\t" \

	"cmpl $0,%0\n\t" \

	"jle 2b\n\t" \

	"jle 3b\n\t" \

	"jmp 1b\n" \

	LOCK_SECTION_END

	"2:\t" \



#define __raw_spin_lock_string_up \

	"\n\tdecl %0"