From 0db20e45b71f4624f7268c5ba46ace4850f978df Mon Sep 17 00:00:00 2001
From: Simon McVittie <simon.mcvittie@collabora.co.uk>
Date: Mon, 15 Apr 2013 21:31:44 +0100
Subject: [PATCH 8/8] Add a statically-initialized implementation of
 _dbus_global_lock() on glibc systems

---
 dbus/dbus-sysdeps-pthread.c  |   53 ++++++++++++++++++++++++++++++++++++++++++
 dbus/dbus-threads-internal.h |    6 +++++
 dbus/dbus-threads.c          |   14 +++++++++++
 3 files changed, 73 insertions(+)

diff --git a/dbus/dbus-sysdeps-pthread.c b/dbus/dbus-sysdeps-pthread.c
index 47e7c0f..2115eb8 100644
--- a/dbus/dbus-sysdeps-pthread.c
+++ b/dbus/dbus-sysdeps-pthread.c
@@ -308,3 +308,56 @@ _dbus_threads_unlock_platform_specific (void)
 {
   pthread_mutex_unlock (&init_mutex);
 }
+
+#ifdef DBUS_HAVE_STATIC_RECURSIVE_MUTEXES
+
+static pthread_mutex_t global_locks[] = {
+    /* 0-4 */
+    PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP,
+    PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP,
+    PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP,
+    PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP,
+    PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP,
+    /* 5-9 */
+    PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP,
+    PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP,
+    PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP,
+    PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP,
+    PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP,
+    /* 10-11 */
+    PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP,
+    PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
+};
+
+_DBUS_STATIC_ASSERT (_DBUS_N_ELEMENTS (global_locks) == _DBUS_N_GLOBAL_LOCKS);
+
+dbus_bool_t
+_dbus_global_lock (DBusGlobalMutex mutex)
+{
+  _dbus_global_lock_cannot_fail (mutex);
+  return TRUE;
+}
+
+void
+_dbus_global_lock_cannot_fail (DBusGlobalMutex mutex)
+{
+  /* No initialization is needed. */
+  _dbus_assert (mutex >= 0);
+  _dbus_assert (mutex < _DBUS_N_GLOBAL_LOCKS);
+
+  PTHREAD_CHECK ("pthread_mutex_lock",
+      pthread_mutex_lock (&(global_locks[mutex])));
+}
+
+dbus_bool_t
+_dbus_global_unlock (DBusGlobalMutex mutex)
+{
+  /* No initialization is needed. */
+  _dbus_assert (mutex >= 0);
+  _dbus_assert (mutex < _DBUS_N_GLOBAL_LOCKS);
+
+  PTHREAD_CHECK ("pthread_mutex_unlock",
+      pthread_mutex_unlock (&(global_locks[mutex])));
+}
+
+#endif
diff --git a/dbus/dbus-threads-internal.h b/dbus/dbus-threads-internal.h
index 79a0be9..3df4547 100644
--- a/dbus/dbus-threads-internal.h
+++ b/dbus/dbus-threads-internal.h
@@ -58,6 +58,12 @@ typedef enum {
     _DBUS_LOCK_INVALID = 10000
 } DBusGlobalMutex;
 
+/* glibc can implement global locks without needing an initialization step,
+ * which improves our thread-safety-by-default further. */
+#if defined(__GLIBC__) && defined(PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP)
+#   define DBUS_HAVE_STATIC_RECURSIVE_MUTEXES 1
+#endif
+
 /**
  * A mutex which is recursive if possible, else non-recursive.
  * This is typically recursive, but that cannot be relied upon.
diff --git a/dbus/dbus-threads.c b/dbus/dbus-threads.c
index f4c068e..e67454d 100644
--- a/dbus/dbus-threads.c
+++ b/dbus/dbus-threads.c
@@ -301,6 +301,18 @@ _dbus_condvar_wake_one (DBusCondVar *cond)
   _dbus_platform_condvar_wake_one (cond);
 }
 
+#ifdef DBUS_HAVE_STATIC_RECURSIVE_MUTEXES
+
+static dbus_bool_t
+init_global_locks (void)
+{
+  return TRUE;
+}
+
+/* implementations in dbus-sysdeps-pthread.c */
+
+#else /* !defined(DBUS_HAVE_STATIC_RECURSIVE_MUTEXES) */
+
 /* All NULL-initialized (ISO C guarantees that partial initializers
  * work like that). */
 static DBusRMutex *global_locks[_DBUS_N_GLOBAL_LOCKS] = { NULL };
@@ -409,6 +421,8 @@ _dbus_global_unlock (DBusGlobalMutex mutex)
   _dbus_platform_rmutex_unlock (global_locks[mutex]);
 }
 
+#endif /* !defined(DBUS_HAVE_STATIC_RECURSIVE_MUTEXES) */
+
 /**
  * Initialize threading in a platform-specific way.
  *
-- 
1.7.10.4