aboutsummaryrefslogtreecommitdiff
path: root/linuxthreads/mutex.c
diff options
context:
space:
mode:
Diffstat (limited to 'linuxthreads/mutex.c')
-rw-r--r--linuxthreads/mutex.c362
1 files changed, 362 insertions, 0 deletions
diff --git a/linuxthreads/mutex.c b/linuxthreads/mutex.c
new file mode 100644
index 0000000000..d5f7a335cc
--- /dev/null
+++ b/linuxthreads/mutex.c
@@ -0,0 +1,362 @@
+/* Linuxthreads - a simple clone()-based implementation of Posix */
+/* threads for Linux. */
+/* Copyright (C) 1996 Xavier Leroy (Xavier.Leroy@inria.fr) */
+/* */
+/* This program is free software; you can redistribute it and/or */
+/* modify it under the terms of the GNU Library General Public License */
+/* as published by the Free Software Foundation; either version 2 */
+/* of the License, or (at your option) any later version. */
+/* */
+/* This program 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 Library General Public License for more details. */
+
+/* Mutexes */
+
+#include <bits/libc-lock.h>
+#include <errno.h>
+#include <sched.h>
+#include <stddef.h>
+#include <limits.h>
+#include "pthread.h"
+#include "internals.h"
+#include "spinlock.h"
+#include "queue.h"
+#include "restart.h"
+
+int __pthread_mutex_init(pthread_mutex_t * mutex,
+ const pthread_mutexattr_t * mutex_attr)
+{
+ __pthread_init_lock(&mutex->__m_lock);
+ mutex->__m_kind =
+ mutex_attr == NULL ? PTHREAD_MUTEX_TIMED_NP : mutex_attr->__mutexkind;
+ mutex->__m_count = 0;
+ mutex->__m_owner = NULL;
+ return 0;
+}
+strong_alias (__pthread_mutex_init, pthread_mutex_init)
+hidden_def (__pthread_mutex_init)
+
+int __pthread_mutex_destroy(pthread_mutex_t * mutex)
+{
+ switch (mutex->__m_kind) {
+ case PTHREAD_MUTEX_ADAPTIVE_NP:
+ case PTHREAD_MUTEX_RECURSIVE_NP:
+ if ((mutex->__m_lock.__status & 1) != 0)
+ return EBUSY;
+ return 0;
+ case PTHREAD_MUTEX_ERRORCHECK_NP:
+ case PTHREAD_MUTEX_TIMED_NP:
+ if (mutex->__m_lock.__status != 0)
+ return EBUSY;
+ return 0;
+ default:
+ return EINVAL;
+ }
+}
+strong_alias (__pthread_mutex_destroy, pthread_mutex_destroy)
+hidden_def (__pthread_mutex_destroy)
+
+int __pthread_mutex_trylock(pthread_mutex_t * mutex)
+{
+ pthread_descr self;
+ int retcode;
+
+ switch(mutex->__m_kind) {
+ case PTHREAD_MUTEX_ADAPTIVE_NP:
+ retcode = __pthread_trylock(&mutex->__m_lock);
+ return retcode;
+ case PTHREAD_MUTEX_RECURSIVE_NP:
+ self = thread_self();
+ if (mutex->__m_owner == self) {
+ mutex->__m_count++;
+ return 0;
+ }
+ retcode = __pthread_trylock(&mutex->__m_lock);
+ if (retcode == 0) {
+ mutex->__m_owner = self;
+ mutex->__m_count = 0;
+ }
+ return retcode;
+ case PTHREAD_MUTEX_ERRORCHECK_NP:
+ retcode = __pthread_alt_trylock(&mutex->__m_lock);
+ if (retcode == 0) {
+ mutex->__m_owner = thread_self();
+ }
+ return retcode;
+ case PTHREAD_MUTEX_TIMED_NP:
+ retcode = __pthread_alt_trylock(&mutex->__m_lock);
+ return retcode;
+ default:
+ return EINVAL;
+ }
+}
+strong_alias (__pthread_mutex_trylock, pthread_mutex_trylock)
+hidden_def (__pthread_mutex_trylock)
+
+int __pthread_mutex_lock(pthread_mutex_t * mutex)
+{
+ pthread_descr self;
+
+ switch(mutex->__m_kind) {
+ case PTHREAD_MUTEX_ADAPTIVE_NP:
+ __pthread_lock(&mutex->__m_lock, NULL);
+ return 0;
+ case PTHREAD_MUTEX_RECURSIVE_NP:
+ self = thread_self();
+ if (mutex->__m_owner == self) {
+ mutex->__m_count++;
+ return 0;
+ }
+ __pthread_lock(&mutex->__m_lock, self);
+ mutex->__m_owner = self;
+ mutex->__m_count = 0;
+ return 0;
+ case PTHREAD_MUTEX_ERRORCHECK_NP:
+ self = thread_self();
+ if (mutex->__m_owner == self) return EDEADLK;
+ __pthread_alt_lock(&mutex->__m_lock, self);
+ mutex->__m_owner = self;
+ return 0;
+ case PTHREAD_MUTEX_TIMED_NP:
+ __pthread_alt_lock(&mutex->__m_lock, NULL);
+ return 0;
+ default:
+ return EINVAL;
+ }
+}
+strong_alias (__pthread_mutex_lock, pthread_mutex_lock)
+hidden_def (__pthread_mutex_lock)
+
+int __pthread_mutex_timedlock (pthread_mutex_t *mutex,
+ const struct timespec *abstime)
+{
+ pthread_descr self;
+ int res;
+
+ if (__builtin_expect (abstime->tv_nsec, 0) < 0
+ || __builtin_expect (abstime->tv_nsec, 0) >= 1000000000)
+ return EINVAL;
+
+ switch(mutex->__m_kind) {
+ case PTHREAD_MUTEX_ADAPTIVE_NP:
+ __pthread_lock(&mutex->__m_lock, NULL);
+ return 0;
+ case PTHREAD_MUTEX_RECURSIVE_NP:
+ self = thread_self();
+ if (mutex->__m_owner == self) {
+ mutex->__m_count++;
+ return 0;
+ }
+ __pthread_lock(&mutex->__m_lock, self);
+ mutex->__m_owner = self;
+ mutex->__m_count = 0;
+ return 0;
+ case PTHREAD_MUTEX_ERRORCHECK_NP:
+ self = thread_self();
+ if (mutex->__m_owner == self) return EDEADLK;
+ res = __pthread_alt_timedlock(&mutex->__m_lock, self, abstime);
+ if (res != 0)
+ {
+ mutex->__m_owner = self;
+ return 0;
+ }
+ return ETIMEDOUT;
+ case PTHREAD_MUTEX_TIMED_NP:
+ /* Only this type supports timed out lock. */
+ return (__pthread_alt_timedlock(&mutex->__m_lock, NULL, abstime)
+ ? 0 : ETIMEDOUT);
+ default:
+ return EINVAL;
+ }
+}
+strong_alias (__pthread_mutex_timedlock, pthread_mutex_timedlock)
+
+int __pthread_mutex_unlock(pthread_mutex_t * mutex)
+{
+ switch (mutex->__m_kind) {
+ case PTHREAD_MUTEX_ADAPTIVE_NP:
+ __pthread_unlock(&mutex->__m_lock);
+ return 0;
+ case PTHREAD_MUTEX_RECURSIVE_NP:
+ if (mutex->__m_owner != thread_self())
+ return EPERM;
+ if (mutex->__m_count > 0) {
+ mutex->__m_count--;
+ return 0;
+ }
+ mutex->__m_owner = NULL;
+ __pthread_unlock(&mutex->__m_lock);
+ return 0;
+ case PTHREAD_MUTEX_ERRORCHECK_NP:
+ if (mutex->__m_owner != thread_self() || mutex->__m_lock.__status == 0)
+ return EPERM;
+ mutex->__m_owner = NULL;
+ __pthread_alt_unlock(&mutex->__m_lock);
+ return 0;
+ case PTHREAD_MUTEX_TIMED_NP:
+ __pthread_alt_unlock(&mutex->__m_lock);
+ return 0;
+ default:
+ return EINVAL;
+ }
+}
+strong_alias (__pthread_mutex_unlock, pthread_mutex_unlock)
+hidden_def (__pthread_mutex_unlock)
+
+int __pthread_mutexattr_init(pthread_mutexattr_t *attr)
+{
+ attr->__mutexkind = PTHREAD_MUTEX_TIMED_NP;
+ return 0;
+}
+strong_alias (__pthread_mutexattr_init, pthread_mutexattr_init)
+
+int __pthread_mutexattr_destroy(pthread_mutexattr_t *attr)
+{
+ return 0;
+}
+strong_alias (__pthread_mutexattr_destroy, pthread_mutexattr_destroy)
+
+int __pthread_mutexattr_settype(pthread_mutexattr_t *attr, int kind)
+{
+ if (kind != PTHREAD_MUTEX_ADAPTIVE_NP
+ && kind != PTHREAD_MUTEX_RECURSIVE_NP
+ && kind != PTHREAD_MUTEX_ERRORCHECK_NP
+ && kind != PTHREAD_MUTEX_TIMED_NP)
+ return EINVAL;
+ attr->__mutexkind = kind;
+ return 0;
+}
+weak_alias (__pthread_mutexattr_settype, pthread_mutexattr_settype)
+strong_alias ( __pthread_mutexattr_settype, __pthread_mutexattr_setkind_np)
+weak_alias (__pthread_mutexattr_setkind_np, pthread_mutexattr_setkind_np)
+
+int __pthread_mutexattr_gettype(const pthread_mutexattr_t *attr, int *kind)
+{
+ *kind = attr->__mutexkind;
+ return 0;
+}
+weak_alias (__pthread_mutexattr_gettype, pthread_mutexattr_gettype)
+strong_alias (__pthread_mutexattr_gettype, __pthread_mutexattr_getkind_np)
+weak_alias (__pthread_mutexattr_getkind_np, pthread_mutexattr_getkind_np)
+
+int __pthread_mutexattr_getpshared (const pthread_mutexattr_t *attr,
+ int *pshared)
+{
+ *pshared = PTHREAD_PROCESS_PRIVATE;
+ return 0;
+}
+weak_alias (__pthread_mutexattr_getpshared, pthread_mutexattr_getpshared)
+
+int __pthread_mutexattr_setpshared (pthread_mutexattr_t *attr, int pshared)
+{
+ if (pshared != PTHREAD_PROCESS_PRIVATE && pshared != PTHREAD_PROCESS_SHARED)
+ return EINVAL;
+
+ /* For now it is not possible to shared a conditional variable. */
+ if (pshared != PTHREAD_PROCESS_PRIVATE)
+ return ENOSYS;
+
+ return 0;
+}
+weak_alias (__pthread_mutexattr_setpshared, pthread_mutexattr_setpshared)
+
+/* Once-only execution */
+
+static pthread_mutex_t once_masterlock = PTHREAD_MUTEX_INITIALIZER;
+static pthread_cond_t once_finished = PTHREAD_COND_INITIALIZER;
+static int fork_generation = 0; /* Child process increments this after fork. */
+
+enum { NEVER = 0, IN_PROGRESS = 1, DONE = 2 };
+
+/* If a thread is canceled while calling the init_routine out of
+ pthread once, this handler will reset the once_control variable
+ to the NEVER state. */
+
+static void pthread_once_cancelhandler(void *arg)
+{
+ pthread_once_t *once_control = arg;
+
+ pthread_mutex_lock(&once_masterlock);
+ *once_control = NEVER;
+ pthread_mutex_unlock(&once_masterlock);
+ pthread_cond_broadcast(&once_finished);
+}
+
+int __pthread_once(pthread_once_t * once_control, void (*init_routine)(void))
+{
+ /* flag for doing the condition broadcast outside of mutex */
+ int state_changed;
+
+ /* Test without locking first for speed */
+ if (*once_control == DONE) {
+ READ_MEMORY_BARRIER();
+ return 0;
+ }
+ /* Lock and test again */
+
+ state_changed = 0;
+
+ pthread_mutex_lock(&once_masterlock);
+
+ /* If this object was left in an IN_PROGRESS state in a parent
+ process (indicated by stale generation field), reset it to NEVER. */
+ if ((*once_control & 3) == IN_PROGRESS && (*once_control & ~3) != fork_generation)
+ *once_control = NEVER;
+
+ /* If init_routine is being called from another routine, wait until
+ it completes. */
+ while ((*once_control & 3) == IN_PROGRESS) {
+ pthread_cond_wait(&once_finished, &once_masterlock);
+ }
+ /* Here *once_control is stable and either NEVER or DONE. */
+ if (*once_control == NEVER) {
+ *once_control = IN_PROGRESS | fork_generation;
+ pthread_mutex_unlock(&once_masterlock);
+ pthread_cleanup_push(pthread_once_cancelhandler, once_control);
+ init_routine();
+ pthread_cleanup_pop(0);
+ pthread_mutex_lock(&once_masterlock);
+ WRITE_MEMORY_BARRIER();
+ *once_control = DONE;
+ state_changed = 1;
+ }
+ pthread_mutex_unlock(&once_masterlock);
+
+ if (state_changed)
+ pthread_cond_broadcast(&once_finished);
+
+ return 0;
+}
+strong_alias (__pthread_once, pthread_once)
+
+/*
+ * Handle the state of the pthread_once mechanism across forks. The
+ * once_masterlock is acquired in the parent process prior to a fork to ensure
+ * that no thread is in the critical region protected by the lock. After the
+ * fork, the lock is released. In the child, the lock and the condition
+ * variable are simply reset. The child also increments its generation
+ * counter which lets pthread_once calls detect stale IN_PROGRESS states
+ * and reset them back to NEVER.
+ */
+
+void __pthread_once_fork_prepare(void)
+{
+ pthread_mutex_lock(&once_masterlock);
+}
+
+void __pthread_once_fork_parent(void)
+{
+ pthread_mutex_unlock(&once_masterlock);
+}
+
+void __pthread_once_fork_child(void)
+{
+ pthread_mutex_init(&once_masterlock, NULL);
+ pthread_cond_init(&once_finished, NULL);
+ if (fork_generation <= INT_MAX - 4)
+ fork_generation += 4; /* leave least significant two bits zero */
+ else
+ fork_generation = 0;
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-05 20:45:18 +0000