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164 lines
5.2 KiB
C
164 lines
5.2 KiB
C
/* Copyright (C) 2002-2024 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <assert.h>
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#include <errno.h>
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#include <stdbool.h>
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#include <string.h>
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#include <kernel-features.h>
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#include "pthreadP.h"
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#include <atomic.h>
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#include <pthread-offsets.h>
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#include <futex-internal.h>
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#include <shlib-compat.h>
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#include <stap-probe.h>
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static const struct pthread_mutexattr default_mutexattr =
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{
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/* Default is a normal mutex, not shared between processes. */
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.mutexkind = PTHREAD_MUTEX_NORMAL
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};
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static bool
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prio_inherit_missing (void)
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{
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static int tpi_supported;
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if (__glibc_unlikely (atomic_load_relaxed (&tpi_supported) == 0))
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{
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int e = futex_unlock_pi (&(unsigned int){0}, 0);
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atomic_store_relaxed (&tpi_supported, e == ENOSYS ? -1 : 1);
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}
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return __glibc_unlikely (tpi_supported < 0);
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}
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int
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___pthread_mutex_init (pthread_mutex_t *mutex,
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const pthread_mutexattr_t *mutexattr)
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{
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const struct pthread_mutexattr *imutexattr;
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ASSERT_TYPE_SIZE (pthread_mutex_t, __SIZEOF_PTHREAD_MUTEX_T);
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/* __kind is the only field where its offset should be checked to
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avoid ABI breakage with static initializers. */
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ASSERT_PTHREAD_INTERNAL_OFFSET (pthread_mutex_t, __data.__kind,
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__PTHREAD_MUTEX_KIND_OFFSET);
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ASSERT_PTHREAD_INTERNAL_MEMBER_SIZE (pthread_mutex_t, __data.__kind, int);
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imutexattr = ((const struct pthread_mutexattr *) mutexattr
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?: &default_mutexattr);
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/* Sanity checks. */
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switch (__builtin_expect (imutexattr->mutexkind
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& PTHREAD_MUTEXATTR_PROTOCOL_MASK,
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PTHREAD_PRIO_NONE
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<< PTHREAD_MUTEXATTR_PROTOCOL_SHIFT))
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{
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case PTHREAD_PRIO_NONE << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
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break;
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case PTHREAD_PRIO_INHERIT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
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if (__glibc_unlikely (prio_inherit_missing ()))
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return ENOTSUP;
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break;
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default:
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/* XXX: For now we don't support robust priority protected mutexes. */
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if (imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_ROBUST)
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return ENOTSUP;
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break;
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}
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/* Clear the whole variable. */
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memset (mutex, '\0', __SIZEOF_PTHREAD_MUTEX_T);
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/* Copy the values from the attribute. */
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int mutex_kind = imutexattr->mutexkind & ~PTHREAD_MUTEXATTR_FLAG_BITS;
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if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_ROBUST) != 0)
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{
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#ifndef __ASSUME_SET_ROBUST_LIST
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if ((imutexattr->mutexkind & PTHREAD_MUTEXATTR_FLAG_PSHARED) != 0
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&& !__nptl_set_robust_list_avail)
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return ENOTSUP;
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#endif
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mutex_kind |= PTHREAD_MUTEX_ROBUST_NORMAL_NP;
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}
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switch (imutexattr->mutexkind & PTHREAD_MUTEXATTR_PROTOCOL_MASK)
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{
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case PTHREAD_PRIO_INHERIT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
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mutex_kind |= PTHREAD_MUTEX_PRIO_INHERIT_NP;
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break;
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case PTHREAD_PRIO_PROTECT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
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mutex_kind |= PTHREAD_MUTEX_PRIO_PROTECT_NP;
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int ceiling = (imutexattr->mutexkind
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& PTHREAD_MUTEXATTR_PRIO_CEILING_MASK)
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>> PTHREAD_MUTEXATTR_PRIO_CEILING_SHIFT;
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if (! ceiling)
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{
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/* See __init_sched_fifo_prio. */
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if (atomic_load_relaxed (&__sched_fifo_min_prio) == -1)
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__init_sched_fifo_prio ();
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if (ceiling < atomic_load_relaxed (&__sched_fifo_min_prio))
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ceiling = atomic_load_relaxed (&__sched_fifo_min_prio);
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}
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mutex->__data.__lock = ceiling << PTHREAD_MUTEX_PRIO_CEILING_SHIFT;
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break;
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default:
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break;
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}
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/* The kernel when waking robust mutexes on exit never uses
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FUTEX_PRIVATE_FLAG FUTEX_WAKE. */
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if ((imutexattr->mutexkind & (PTHREAD_MUTEXATTR_FLAG_PSHARED
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| PTHREAD_MUTEXATTR_FLAG_ROBUST)) != 0)
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mutex_kind |= PTHREAD_MUTEX_PSHARED_BIT;
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/* See concurrency notes regarding __kind in struct __pthread_mutex_s
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in sysdeps/nptl/bits/thread-shared-types.h. */
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atomic_store_relaxed (&(mutex->__data.__kind), mutex_kind);
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/* Default values: mutex not used yet. */
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// mutex->__count = 0; already done by memset
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// mutex->__owner = 0; already done by memset
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// mutex->__nusers = 0; already done by memset
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// mutex->__spins = 0; already done by memset
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// mutex->__next = NULL; already done by memset
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LIBC_PROBE (mutex_init, 1, mutex);
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return 0;
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}
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versioned_symbol (libpthread, ___pthread_mutex_init, pthread_mutex_init,
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GLIBC_2_0);
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libc_hidden_ver (___pthread_mutex_init, __pthread_mutex_init)
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#ifndef SHARED
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strong_alias (___pthread_mutex_init, __pthread_mutex_init)
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#endif
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#if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_34)
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compat_symbol (libpthread, ___pthread_mutex_init, __pthread_mutex_init,
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GLIBC_2_0);
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#endif
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