futex_requeue_pi optimization
This patch provides the futex_requeue_pi functionality, which allows some
threads waiting on a normal futex to be requeued on the wait-queue of a
PI-futex.
This provides an optimization, already used for (normal) futexes, to be used
with the PI-futexes.
This optimization is currently used by the glibc in pthread_broadcast, when
using "normal" mutexes. With futex_requeue_pi, it can be used with
PRIO_INHERIT mutexes too.
Signed-off-by: Pierre Peiffer <pierre.peiffer@bull.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/rtmutex_common.h b/kernel/rtmutex_common.h
index 9c75856..242ec7e 100644
--- a/kernel/rtmutex_common.h
+++ b/kernel/rtmutex_common.h
@@ -113,6 +113,29 @@
}
/*
+ * We can speed up the acquire/release, if the architecture
+ * supports cmpxchg and if there's no debugging state to be set up
+ */
+#if defined(__HAVE_ARCH_CMPXCHG) && !defined(CONFIG_DEBUG_RT_MUTEXES)
+# define rt_mutex_cmpxchg(l,c,n) (cmpxchg(&l->owner, c, n) == c)
+static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
+{
+ unsigned long owner, *p = (unsigned long *) &lock->owner;
+
+ do {
+ owner = *p;
+ } while (cmpxchg(p, owner, owner | RT_MUTEX_HAS_WAITERS) != owner);
+}
+#else
+# define rt_mutex_cmpxchg(l,c,n) (0)
+static inline void mark_rt_mutex_waiters(struct rt_mutex *lock)
+{
+ lock->owner = (struct task_struct *)
+ ((unsigned long)lock->owner | RT_MUTEX_HAS_WAITERS);
+}
+#endif
+
+/*
* PI-futex support (proxy locking functions, etc.):
*/
extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
@@ -120,4 +143,15 @@
struct task_struct *proxy_owner);
extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
struct task_struct *proxy_owner);
+
+extern void rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner,
+ unsigned long mask);
+extern void __rt_mutex_adjust_prio(struct task_struct *task);
+extern int rt_mutex_adjust_prio_chain(struct task_struct *task,
+ int deadlock_detect,
+ struct rt_mutex *orig_lock,
+ struct rt_mutex_waiter *orig_waiter,
+ struct task_struct *top_task);
+extern void remove_waiter(struct rt_mutex *lock,
+ struct rt_mutex_waiter *waiter);
#endif