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/* 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)

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)

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)

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)

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)

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)

#if !defined(_ELIX_LEVEL) || _ELIX_LEVEL >= 2

strong_alias ( __pthread_mutexattr_settype, __pthread_mutexattr_setkind_np)

weak_alias (__pthread_mutexattr_setkind_np, pthread_mutexattr_setkind_np)

#endif /* !_ELIX_LEVEL || _ELIX_LEVEL >= 2 */

int __pthread_mutexattr_gettype(const pthread_mutexattr_t *attr, int *kind)

{

  *kind = attr->__mutexkind;

  return 0;

}

weak_alias (__pthread_mutexattr_gettype, pthread_mutexattr_gettype)

#if !defined(_ELIX_LEVEL) || _ELIX_LEVEL >= 2

strong_alias (__pthread_mutexattr_gettype, __pthread_mutexattr_getkind_np)

weak_alias (__pthread_mutexattr_getkind_np, pthread_mutexattr_getkind_np)

#endif /* !_ELIX_LEVEL || _ELIX_LEVEL >= 2 */

#if !defined(_ELIX_LEVEL) || _ELIX_LEVEL >= 3

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)

#endif /* !_ELIX_LEVEL || _ELIX_LEVEL >= 3 */

/* 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;

}