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glibc/nptl/pthread_mutex_lock.c
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/* 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. | |
The GNU C Library is free software; you can redistribute it and/or | |
modify it under the terms of the GNU Lesser General Public | |
License as published by the Free Software Foundation; either | |
version 2.1 of the License, or (at your option) any later version. | |
The GNU C Library is distributed in the hope that it will be useful, | |
but WITHOUT ANY WARRANTY; without even the implied warranty of | |
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
Lesser General Public License for more details. | |
You should have received a copy of the GNU Lesser General Public | |
License along with the GNU C Library; if not, write to the Free | |
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | |
02111-1307 USA. */ | |
#include <assert.h> | |
#include <errno.h> | |
#include "pthreadP.h" | |
#include <lowlevellock.h> | |
#ifndef LLL_MUTEX_LOCK | |
# define LLL_MUTEX_LOCK(mutex) lll_mutex_lock (mutex) | |
# define LLL_MUTEX_TRYLOCK(mutex) lll_mutex_trylock (mutex) | |
#endif | |
int | |
__pthread_mutex_lock (mutex) | |
pthread_mutex_t *mutex; | |
{ | |
assert (sizeof (mutex->__size) >= sizeof (mutex->__data)); | |
pid_t id = THREAD_GETMEM (THREAD_SELF, tid); | |
switch (__builtin_expect (mutex->__data.__kind, PTHREAD_MUTEX_TIMED_NP)) | |
{ | |
/* Recursive mutex. */ | |
case PTHREAD_MUTEX_RECURSIVE_NP: | |
/* Check whether we already hold the mutex. */ | |
if (mutex->__data.__owner == id) | |
{ | |
/* Just bump the counter. */ | |
if (__builtin_expect (mutex->__data.__count + 1 == 0, 0)) | |
/* Overflow of the counter. */ | |
return EAGAIN; | |
++mutex->__data.__count; | |
return 0; | |
} | |
/* We have to get the mutex. */ | |
LLL_MUTEX_LOCK (mutex->__data.__lock); | |
mutex->__data.__count = 1; | |
break; | |
/* Error checking mutex. */ | |
case PTHREAD_MUTEX_ERRORCHECK_NP: | |
/* Check whether we already hold the mutex. */ | |
if (mutex->__data.__owner == id) | |
return EDEADLK; | |
/* FALLTHROUGH */ | |
default: | |
/* Correct code cannot set any other type. */ | |
case PTHREAD_MUTEX_TIMED_NP: | |
simple: | |
/* Normal mutex. */ | |
LLL_MUTEX_LOCK (mutex->__data.__lock); | |
break; | |
case PTHREAD_MUTEX_ADAPTIVE_NP: | |
if (! __is_smp) | |
goto simple; | |
if (LLL_MUTEX_TRYLOCK (mutex->__data.__lock) != 0) | |
{ | |
int cnt = 0; | |
int max_cnt = MIN (MAX_ADAPTIVE_COUNT, | |
mutex->__data.__spins * 2 + 10); | |
do | |
{ | |
if (cnt++ >= max_cnt) | |
{ | |
LLL_MUTEX_LOCK (mutex->__data.__lock); | |
break; | |
} | |
#ifdef BUSY_WAIT_NOP | |
BUSY_WAIT_NOP; | |
#endif | |
} | |
while (LLL_MUTEX_TRYLOCK (mutex->__data.__lock) != 0); | |
mutex->__data.__spins += (cnt - mutex->__data.__spins) / 8; | |
} | |
break; | |
} | |
/* Record the ownership. */ | |
assert (mutex->__data.__owner == 0); | |
mutex->__data.__owner = id; | |
#ifndef NO_INCR | |
++mutex->__data.__nusers; | |
#endif | |
return 0; | |
} | |
#ifndef __pthread_mutex_lock | |
strong_alias (__pthread_mutex_lock, pthread_mutex_lock) | |
strong_alias (__pthread_mutex_lock, __pthread_mutex_lock_internal) | |
#endif |