Messages in this thread Patch in this message | | | Date | Thu, 29 Dec 2005 22:03:46 +0100 | From | Ingo Molnar <> | Subject | [patch 04/13] mutex subsystem, add include/asm-x86_64/mutex.h |
| |
add the x86_64 version of mutex.h, optimized in assembly.
Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@infradead.org>
----
include/asm-x86_64/mutex.h | 97 +++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 97 insertions(+)
Index: linux/include/asm-x86_64/mutex.h =================================================================== --- /dev/null +++ linux/include/asm-x86_64/mutex.h @@ -0,0 +1,97 @@ +/* + * Assembly implementation of the mutex fastpath, based on atomic + * decrement/increment. + * + * started by Ingo Molnar: + * + * Copyright (C) 2004, 2005 Red Hat, Inc., Ingo Molnar <mingo@redhat.com> + */ +#ifndef _ASM_MUTEX_H +#define _ASM_MUTEX_H + +/** + * __mutex_fastpath_lock - decrement and call function if negative + * @v: pointer of type atomic_t + * @fn: function to call if the result is negative + * + * Atomically decrements @v and calls <fn> if the result is negative. + */ +#define __mutex_fastpath_lock(v, fn_name) \ +do { \ + /* type-check the function too: */ \ + fastcall void (*__tmp)(atomic_t *) = fn_name; \ + unsigned long dummy; \ + \ + (void)__tmp; \ + typecheck(atomic_t *, v); \ + \ + __asm__ __volatile__( \ + LOCK " decl (%%rdi) \n" \ + " js 2f \n" \ + "1: \n" \ + \ + LOCK_SECTION_START("") \ + "2: call "#fn_name" \n" \ + " jmp 1b \n" \ + LOCK_SECTION_END \ + \ + :"=D" (dummy) \ + : "D" (v) \ + : "rax", "rsi", "rdx", "rcx", \ + "r8", "r9", "r10", "r11", "memory"); \ +} while (0) + +/** + * __mutex_fastpath_unlock - increment and call function if nonpositive + * @v: pointer of type atomic_t + * @fn: function to call if the result is nonpositive + * + * Atomically increments @v and calls <fn> if the result is nonpositive. + */ +#define __mutex_fastpath_unlock(v, fn_name) \ +do { \ + /* type-check the function too: */ \ + fastcall void (*__tmp)(atomic_t *) = fn_name; \ + unsigned long dummy; \ + \ + (void)__tmp; \ + typecheck(atomic_t *, v); \ + \ + __asm__ __volatile__( \ + LOCK " incl (%%rdi) \n" \ + " jle 2f \n" \ + "1: \n" \ + \ + LOCK_SECTION_START("") \ + "2: call "#fn_name" \n" \ + " jmp 1b \n" \ + LOCK_SECTION_END \ + \ + :"=D" (dummy) \ + : "D" (v) \ + : "rax", "rsi", "rdx", "rcx", \ + "r8", "r9", "r10", "r11", "memory"); \ +} while (0) + +#define __mutex_slowpath_needs_to_unlock() 1 + +/** + * __mutex_fastpath_trylock - try to acquire the mutex, without waiting + * + * @count: pointer of type atomic_t + * @fn: fallback function + * + * Change the count from 1 to 0 and return 1 (success), or return 0 (failure) + * if it wasn't 1 originally. [the fallback function is never used on + * x86_64, because all x86_64 CPUs have a CMPXCHG instruction.] + */ +static inline int +__mutex_fastpath_trylock(atomic_t *count, int (*fn)(atomic_t *)) +{ + if (likely(atomic_cmpxchg(count, 1, 0)) == 1) + return 1; + else + return 0; +} + +#endif - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |