Major update for pthreads, based in large part on improvements

from glibc 2.3.  This should make threads much more efficient.
 -Erik

1 files changed, 176 insertions, 40 deletions

diff --git a/libpthread/linuxthreads/mutex.c b/libpthread/linuxthreads/mutex.c
index 2ab9e7e55..3c97ea7d6 100644
--- a/libpthread/linuxthreads/mutex.c
+++ b/libpthread/linuxthreads/mutex.c
@@ -12,41 +12,51 @@
 /* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the        */
 /* GNU Library General Public License for more details.                 */
 
-/* changes for uClibc: remove strong_alias'es and define the real symbol */
-
 /* Mutexes */
 
-#include <features.h>
-#define __USE_GNU
+#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,
+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_ADAPTIVE_NP : mutex_attr->__mutexkind;
+    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)
+strong_alias (__pthread_mutex_init, pthread_mutex_init)
 
-int pthread_mutex_destroy(pthread_mutex_t * mutex)
+int __pthread_mutex_destroy(pthread_mutex_t * mutex)
 {
-  if (mutex->__m_lock.__status != 0) return EBUSY;
-  return 0;
+  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)
+strong_alias (__pthread_mutex_destroy, pthread_mutex_destroy)
 
-int pthread_mutex_trylock(pthread_mutex_t * mutex)
+int __pthread_mutex_trylock(pthread_mutex_t * mutex)
 {
   pthread_descr self;
   int retcode;
@@ -68,18 +78,21 @@ int pthread_mutex_trylock(pthread_mutex_t * mutex)
     }
     return retcode;
   case PTHREAD_MUTEX_ERRORCHECK_NP:
-    retcode = __pthread_trylock(&mutex->__m_lock);
+    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)
+strong_alias (__pthread_mutex_trylock, pthread_mutex_trylock)
 
-int pthread_mutex_lock(pthread_mutex_t * mutex)
+int __pthread_mutex_lock(pthread_mutex_t * mutex)
 {
   pthread_descr self;
 
@@ -100,22 +113,71 @@ int pthread_mutex_lock(pthread_mutex_t * mutex)
   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_lock, pthread_mutex_lock)
+strong_alias (__pthread_mutex_timedlock, pthread_mutex_timedlock)
 
-int pthread_mutex_unlock(pthread_mutex_t * mutex)
+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;
@@ -127,38 +189,42 @@ int pthread_mutex_unlock(pthread_mutex_t * mutex)
     if (mutex->__m_owner != thread_self() || mutex->__m_lock.__status == 0)
       return EPERM;
     mutex->__m_owner = NULL;
-    __pthread_unlock(&mutex->__m_lock);
+    __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)
+strong_alias (__pthread_mutex_unlock, pthread_mutex_unlock)
 
-int pthread_mutexattr_init(pthread_mutexattr_t *attr)
+int __pthread_mutexattr_init(pthread_mutexattr_t *attr)
 {
-  attr->__mutexkind = PTHREAD_MUTEX_ADAPTIVE_NP;
+  attr->__mutexkind = PTHREAD_MUTEX_TIMED_NP;
   return 0;
 }
-//strong_alias (__pthread_mutexattr_init, pthread_mutexattr_init)
+strong_alias (__pthread_mutexattr_init, pthread_mutexattr_init)
 
-int pthread_mutexattr_destroy(pthread_mutexattr_t *attr)
+int __pthread_mutexattr_destroy(pthread_mutexattr_t *attr)
 {
   return 0;
 }
-//strong_alias (__pthread_mutexattr_destroy, pthread_mutexattr_destroy)
+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_ERRORCHECK_NP
+      && kind != PTHREAD_MUTEX_TIMED_NP)
     return EINVAL;
   attr->__mutexkind = kind;
   return 0;
 }
 weak_alias (__pthread_mutexattr_settype, pthread_mutexattr_settype)
-weak_alias ( __pthread_mutexattr_settype, __pthread_mutexattr_setkind_np)
+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)
@@ -167,24 +233,27 @@ int __pthread_mutexattr_gettype(const pthread_mutexattr_t *attr, int *kind)
   return 0;
 }
 weak_alias (__pthread_mutexattr_gettype, pthread_mutexattr_gettype)
-weak_alias (__pthread_mutexattr_gettype, __pthread_mutexattr_getkind_np)
+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)
+int __pthread_mutexattr_getpshared (const pthread_mutexattr_t *attr,
+				   int *pshared)
 {
-    *pshared = PTHREAD_PROCESS_PRIVATE;
-    return 0;
+  *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;
+  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)
 
@@ -192,30 +261,97 @@ weak_alias (__pthread_mutexattr_setpshared, pthread_mutexattr_setpshared)
 
 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) return 0;
+  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 == IN_PROGRESS) {
+  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;
+    *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;
-    pthread_cond_broadcast(&once_finished);
+    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;
+}