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glibc/nptl/pthread_mutex_init.c
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/* Copyright (C) 2002-2016 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, see | |
<http://www.gnu.org/licenses/>. */ | |
#include <assert.h> | |
#include <errno.h> | |
#include <stdbool.h> | |
#include <string.h> | |
#include <kernel-features.h> | |
#include "pthreadP.h" | |
#include <atomic.h> | |
#include <stap-probe.h> | |
static const struct pthread_mutexattr default_mutexattr = | |
{ | |
/* Default is a normal mutex, not shared between processes. */ | |
.mutexkind = PTHREAD_MUTEX_NORMAL | |
}; | |
static bool | |
prio_inherit_missing (void) | |
{ | |
#ifdef __NR_futex | |
# ifndef __ASSUME_FUTEX_LOCK_PI | |
static int tpi_supported; | |
if (__glibc_unlikely (tpi_supported == 0)) | |
{ | |
int lock = 0; | |
INTERNAL_SYSCALL_DECL (err); | |
int ret = INTERNAL_SYSCALL (futex, err, 4, &lock, FUTEX_UNLOCK_PI, 0, 0); | |
assert (INTERNAL_SYSCALL_ERROR_P (ret, err)); | |
tpi_supported = INTERNAL_SYSCALL_ERRNO (ret, err) == ENOSYS ? -1 : 1; | |
} | |
return __glibc_unlikely (tpi_supported < 0); | |
# endif | |
return false; | |
#endif | |
return true; | |
} | |
int | |
__pthread_mutex_init (pthread_mutex_t *mutex, | |
const pthread_mutexattr_t *mutexattr) | |
{ | |
const struct pthread_mutexattr *imutexattr; | |
assert (sizeof (pthread_mutex_t) <= __SIZEOF_PTHREAD_MUTEX_T); | |
imutexattr = ((const struct pthread_mutexattr *) mutexattr | |
?: &default_mutexattr); | |
/* Sanity checks. */ | |
switch (__builtin_expect (imutexattr->mutexkind | |
& PTHREAD_MUTEXATTR_PROTOCOL_MASK, | |
PTHREAD_PRIO_NONE | |
<< PTHREAD_MUTEXATTR_PROTOCOL_SHIFT)) | |
{ | |
case PTHREAD_PRIO_NONE << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT: | |
break; | |
case PTHREAD_PRIO_INHERIT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT: | |
if (__glibc_unlikely (prio_inherit_missing ())) | |
return ENOTSUP; | |
break; | |
default: | |
/* XXX: For now we don't support robust priority protected mutexes. */ | |
if (imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_ROBUST) | |
return ENOTSUP; | |
break; | |
} | |
/* Clear the whole variable. */ | |
memset (mutex, '\0', __SIZEOF_PTHREAD_MUTEX_T); | |
/* Copy the values from the attribute. */ | |
mutex->__data.__kind = imutexattr->mutexkind & ~PTHREAD_MUTEXATTR_FLAG_BITS; | |
if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_ROBUST) != 0) | |
{ | |
#ifndef __ASSUME_SET_ROBUST_LIST | |
if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_PSHARED) != 0 | |
&& __set_robust_list_avail < 0) | |
return ENOTSUP; | |
#endif | |
mutex->__data.__kind |= PTHREAD_MUTEX_ROBUST_NORMAL_NP; | |
} | |
switch (imutexattr->mutexkind & PTHREAD_MUTEXATTR_PROTOCOL_MASK) | |
{ | |
case PTHREAD_PRIO_INHERIT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT: | |
mutex->__data.__kind |= PTHREAD_MUTEX_PRIO_INHERIT_NP; | |
break; | |
case PTHREAD_PRIO_PROTECT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT: | |
mutex->__data.__kind |= PTHREAD_MUTEX_PRIO_PROTECT_NP; | |
int ceiling = (imutexattr->mutexkind | |
& PTHREAD_MUTEXATTR_PRIO_CEILING_MASK) | |
>> PTHREAD_MUTEXATTR_PRIO_CEILING_SHIFT; | |
if (! ceiling) | |
{ | |
/* See __init_sched_fifo_prio. */ | |
if (atomic_load_relaxed (&__sched_fifo_min_prio) == -1) | |
__init_sched_fifo_prio (); | |
if (ceiling < atomic_load_relaxed (&__sched_fifo_min_prio)) | |
ceiling = atomic_load_relaxed (&__sched_fifo_min_prio); | |
} | |
mutex->__data.__lock = ceiling << PTHREAD_MUTEX_PRIO_CEILING_SHIFT; | |
break; | |
default: | |
break; | |
} | |
/* The kernel when waking robust mutexes on exit never uses | |
FUTEX_PRIVATE_FLAG FUTEX_WAKE. */ | |
if ((imutexattr->mutexkind & (PTHREAD_MUTEXATTR_FLAG_PSHARED | |
| PTHREAD_MUTEXATTR_FLAG_ROBUST)) != 0) | |
mutex->__data.__kind |= PTHREAD_MUTEX_PSHARED_BIT; | |
/* Default values: mutex not used yet. */ | |
// mutex->__count = 0; already done by memset | |
// mutex->__owner = 0; already done by memset | |
// mutex->__nusers = 0; already done by memset | |
// mutex->__spins = 0; already done by memset | |
// mutex->__next = NULL; already done by memset | |
LIBC_PROBE (mutex_init, 1, mutex); | |
return 0; | |
} | |
strong_alias (__pthread_mutex_init, pthread_mutex_init) | |
hidden_def (__pthread_mutex_init) |