From 3dc444917b0a2ed9fe28fc6327a57a60533530b9 Mon Sep 17 00:00:00 2001 From: Simon McVittie Date: Tue, 14 Feb 2012 18:38:48 +0000 Subject: [PATCH 3/7] Allow both recursive and non-recursive mutexes to be supplied Bug: https://bugs.freedesktop.org/show_bug.cgi?id=43744 Signed-off-by: Simon McVittie --- dbus/dbus-threads.c | 19 ++++++++++--------- dbus/dbus-threads.h | 23 +++++++---------------- 2 files changed, 17 insertions(+), 25 deletions(-) diff --git a/dbus/dbus-threads.c b/dbus/dbus-threads.c index eff3054..8130847 100644 --- a/dbus/dbus-threads.c +++ b/dbus/dbus-threads.c @@ -734,13 +734,6 @@ dbus_threads_init (const DBusThreadFunctions *functions) "functions sets should be passed into " "dbus_threads_init. Neither sets were passed."); - if (mutex_set && recursive_mutex_set) - _dbus_assert_not_reached ("Either the nonrecusrive or recursive mutex " - "functions sets should be passed into " - "dbus_threads_init. Both sets were passed. " - "You most likely just want to set the recursive " - "mutex functions to avoid deadlocks in D-Bus."); - /* Check that all bits in the mask actually are valid mask bits. * ensures people won't write code that breaks when we add * new bits. @@ -770,15 +763,23 @@ dbus_threads_init (const DBusThreadFunctions *functions) if (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_NEW_MASK) thread_functions.recursive_mutex_new = functions->recursive_mutex_new; - + else + thread_functions.recursive_mutex_new = NULL; + if (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_FREE_MASK) thread_functions.recursive_mutex_free = functions->recursive_mutex_free; - + else + thread_functions.recursive_mutex_free = NULL; + if (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_LOCK_MASK) thread_functions.recursive_mutex_lock = functions->recursive_mutex_lock; + else + thread_functions.recursive_mutex_lock = NULL; if (functions->mask & DBUS_THREAD_FUNCTIONS_RECURSIVE_MUTEX_UNLOCK_MASK) thread_functions.recursive_mutex_unlock = functions->recursive_mutex_unlock; + else + thread_functions.recursive_mutex_unlock = NULL; thread_functions.mask = functions->mask; diff --git a/dbus/dbus-threads.h b/dbus/dbus-threads.h index ba07ca5..6d28a0b 100644 --- a/dbus/dbus-threads.h +++ b/dbus/dbus-threads.h @@ -139,24 +139,15 @@ typedef enum /** * Functions that must be implemented to make the D-Bus library - * thread-aware. The recursive mutex functions should be specified - * rather than the old, deprecated nonrecursive ones. + * thread-aware. * - * The condition variable functions have to work with recursive - * mutexes if you provide those, or with nonrecursive mutexes if you - * provide those. + * If you supply both recursive and non-recursive mutexes, + * libdbus will use the non-recursive version for condition variables, + * and the recursive version in other contexts. * - * If implementing threads using pthreads, be aware that - * PTHREAD_MUTEX_RECURSIVE is broken in combination with condition - * variables. libdbus relies on the Java-style behavior that when - * waiting on a condition, the recursion count is saved and restored, - * and the mutex is completely unlocked, not just decremented one - * level of recursion. - * - * Thus with pthreads you probably have to roll your own emulated - * recursive mutexes, you can't use PTHREAD_MUTEX_RECURSIVE. This is - * what dbus_threads_init_default() does on platforms that use - * pthreads. + * The condition variable functions have to work with nonrecursive + * mutexes if you provide those, or with recursive mutexes if you + * don't. */ typedef struct { -- 1.7.9