Commit 365bf8ac authored by Nicolas Pitre's avatar Nicolas Pitre Committed by Russell King
Browse files

[ARM] 3311/1: clean up include/asm-arm/mutex.h 



Patch from Nicolas Pitre

Since:

	if (unlikely(__res || __ex_flag))

produces worse code on ARM than:

	if (unlikely(__res | __ex_flag))

I therefore made it more explicit:

	__res |= __ex_flag;
	if (unlikely(__res != 0))

so it is not seen as a typo again.

Also made everything static inline rather than macros for better readability
(both produce the same code after all).

And finally added missing \t from multi-line assembly code.

Signed-off-by: default avatarNicolas Pitre <nico@cam.org>
Acked-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 5964eae8

include/asm-arm/mutex.h

+65 −66
Original line number Diff line number Diff line
@@ -23,72 +23,71 @@ 
 * simply bail out immediately through the slow path where the lock will be

 * reattempted until it succeeds.

 */

#define __mutex_fastpath_lock(count, fail_fn)				\

do {									\

	int __ex_flag, __res;						\

									\

	typecheck(atomic_t *, count);					\

	typecheck_fn(fastcall void (*)(atomic_t *), fail_fn);		\

									\

	__asm__ (							\

		"ldrex	%0, [%2]	\n"				\

		"sub	%0, %0, #1	\n"				\

		"strex	%1, %0, [%2]	\n"				\

									\

		: "=&r" (__res), "=&r" (__ex_flag)			\

		: "r" (&(count)->counter)				\

		: "cc","memory" );					\

									\

	if (unlikely(__res || __ex_flag))				\

		fail_fn(count);						\

} while (0)



#define __mutex_fastpath_lock_retval(count, fail_fn)			\

({									\

	int __ex_flag, __res;						\

									\

	typecheck(atomic_t *, count);					\

	typecheck_fn(fastcall int (*)(atomic_t *), fail_fn);		\

									\

	__asm__ (							\

		"ldrex	%0, [%2]	\n"				\

		"sub	%0, %0, #1	\n"				\

		"strex	%1, %0, [%2]	\n"				\

									\

		: "=&r" (__res), "=&r" (__ex_flag)			\

		: "r" (&(count)->counter)				\

		: "cc","memory" );					\

									\

	__res |= __ex_flag;						\

	if (unlikely(__res != 0))					\

		__res = fail_fn(count);					\

	__res;								\

})

static inline void

__mutex_fastpath_lock(atomic_t *count, fastcall void (*fail_fn)(atomic_t *))

{

	int __ex_flag, __res;



	__asm__ (



		"ldrex	%0, [%2]	\n\t"

		"sub	%0, %0, #1	\n\t"

		"strex	%1, %0, [%2]	"



		: "=&r" (__res), "=&r" (__ex_flag)

		: "r" (&(count)->counter)

		: "cc","memory" );



	__res |= __ex_flag;

	if (unlikely(__res != 0))

		fail_fn(count);

}



static inline int

__mutex_fastpath_lock_retval(atomic_t *count, fastcall int (*fail_fn)(atomic_t *))

{

	int __ex_flag, __res;



	__asm__ (



		"ldrex	%0, [%2]	\n\t"

		"sub	%0, %0, #1	\n\t"

		"strex	%1, %0, [%2]	"



		: "=&r" (__res), "=&r" (__ex_flag)

		: "r" (&(count)->counter)

		: "cc","memory" );



	__res |= __ex_flag;

	if (unlikely(__res != 0))

		__res = fail_fn(count);

	return __res;

}



/*

 * Same trick is used for the unlock fast path. However the original value,

 * rather than the result, is used to test for success in order to have

 * better generated assembly.

 */

#define __mutex_fastpath_unlock(count, fail_fn)				\

do {									\

	int __ex_flag, __res, __orig;					\

									\

	typecheck(atomic_t *, count);					\

	typecheck_fn(fastcall void (*)(atomic_t *), fail_fn);		\

									\

	__asm__ (							\

		"ldrex	%0, [%3]	\n"				\

		"add	%1, %0, #1	\n"				\

		"strex	%2, %1, [%3]	\n"				\

									\

		: "=&r" (__orig), "=&r" (__res), "=&r" (__ex_flag)	\

		: "r" (&(count)->counter)				\

		: "cc","memory" );					\

									\

	if (unlikely(__orig || __ex_flag))				\

		fail_fn(count);						\

} while (0)

static inline void

__mutex_fastpath_unlock(atomic_t *count, fastcall void (*fail_fn)(atomic_t *))

{

	int __ex_flag, __res, __orig;



	__asm__ (



		"ldrex	%0, [%3]	\n\t"

		"add	%1, %0, #1	\n\t"

		"strex	%2, %1, [%3]	"



		: "=&r" (__orig), "=&r" (__res), "=&r" (__ex_flag)

		: "r" (&(count)->counter)

		: "cc","memory" );



	__orig |= __ex_flag;

	if (unlikely(__orig != 0))

		fail_fn(count);

}



/*

 * If the unlock was done on a contended lock, or if the unlock simply fails
@@ -110,12 +109,12 @@ __mutex_fastpath_trylock(atomic_t *count, int (*fail_fn)(atomic_t *)) 


	__asm__ (



		"1: ldrex	%0, [%3]	\n"

		"subs		%1, %0, #1	\n"

		"strexeq	%2, %1, [%3]	\n"

		"movlt		%0, #0		\n"

		"cmpeq		%2, #0		\n"

		"bgt		1b		\n"

		"1: ldrex	%0, [%3]	\n\t"

		"subs		%1, %0, #1	\n\t"

		"strexeq	%2, %1, [%3]	\n\t"

		"movlt		%0, #0		\n\t"

		"cmpeq		%2, #0		\n\t"

		"bgt		1b		"



		: "=&r" (__orig), "=&r" (__res), "=&r" (__ex_flag)

		: "r" (&count->counter)

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