diff options
Diffstat (limited to 'nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.h')
| -rw-r--r-- | nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.h | 25 |
1 files changed, 22 insertions, 3 deletions
diff --git a/nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.h b/nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.h index 156d1f7c64..ca8d568038 100644 --- a/nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.h +++ b/nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.h @@ -1,4 +1,4 @@ -/* Copyright (C) 2002, 2003 Free Software Foundation, Inc. +/* Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc. This file is part of the GNU C Library. Contributed by Ulrich Drepper <drepper@redhat.com>, 2002. @@ -40,6 +40,10 @@ /* Initializer for compatibility lock. */ #define LLL_MUTEX_LOCK_INITIALIZER (0) #define LLL_MUTEX_LOCK_INITIALIZER_LOCKED (1) +#define LLL_MUTEX_LOCK_INITIALIZER_WAITERS (2) + +/* Delay in spinlock loop. */ +#define BUSY_WAIT_NOP asm ("rep; nop") #define lll_futex_wait(futex, val) \ @@ -77,9 +81,14 @@ extern int __lll_mutex_timedlock_wait (int *__futex, int __val, extern int __lll_mutex_unlock_wait (int *__futex) attribute_hidden; +/* NB: in the lll_mutex_trylock macro we simply return the value in %eax + after the cmpxchg instruction. In case the operation succeded this + value is zero. In case the operation failed, the cmpxchg instruction + has loaded the current value of the memory work which is guaranteed + to be nonzero. */ #define lll_mutex_trylock(futex) \ - ({ unsigned char ret; \ - __asm __volatile (LOCK_INSTR "cmpxchgl %2, %1; setne %0" \ + ({ int ret; \ + __asm __volatile (LOCK_INSTR "cmpxchgl %2, %1" \ : "=a" (ret), "=m" (futex) \ : "r" (LLL_MUTEX_LOCK_INITIALIZER_LOCKED), "m" (futex),\ "0" (LLL_MUTEX_LOCK_INITIALIZER) \ @@ -87,6 +96,16 @@ extern int __lll_mutex_unlock_wait (int *__futex) attribute_hidden; ret; }) +#define lll_mutex_cond_trylock(futex) \ + ({ int ret; \ + __asm __volatile (LOCK_INSTR "cmpxchgl %2, %1" \ + : "=a" (ret), "=m" (futex) \ + : "r" (LLL_MUTEX_LOCK_INITIALIZER_WAITERS), \ + "m" (futex), "0" (LLL_MUTEX_LOCK_INITIALIZER) \ + : "memory"); \ + ret; }) + + #define lll_mutex_lock(futex) \ (void) ({ int ignore1, ignore2, ignore3; \ __asm __volatile (LOCK_INSTR "cmpxchgl %0, %2\n\t" \ |