From: Ingo Molnar <[email protected]>
add proxy-locking rt-mutex functionality needed by pi-futexes.
Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Arjan van de Ven <[email protected]>
----
include/linux/rtmutex_internal.h | 8 +++++
kernel/rtmutex.c | 55 +++++++++++++++++++++++++++++++++++++++
2 files changed, 63 insertions(+)
Index: linux-pi-futex.mm.q/include/linux/rtmutex_internal.h
===================================================================
--- linux-pi-futex.mm.q.orig/include/linux/rtmutex_internal.h
+++ linux-pi-futex.mm.q/include/linux/rtmutex_internal.h
@@ -176,4 +176,12 @@ static inline void mark_rt_mutex_waiters
#endif
+/*
+ * PI-futex support (proxy locking functions, etc.):
+ */
+extern struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock);
+extern void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
+ struct task_struct *proxy_owner);
+extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
+ struct task_struct *proxy_owner);
#endif
Index: linux-pi-futex.mm.q/kernel/rtmutex.c
===================================================================
--- linux-pi-futex.mm.q.orig/kernel/rtmutex.c
+++ linux-pi-futex.mm.q/kernel/rtmutex.c
@@ -940,3 +940,58 @@ void fastcall __rt_mutex_init(struct rt_
debug_rt_mutex_init(lock, name);
}
EXPORT_SYMBOL_GPL(__rt_mutex_init);
+
+/**
+ * rt_mutex_init_proxy_locked - initialize and lock a rt_mutex on behalf of a
+ * proxy owner
+ *
+ * @lock: the rt_mutex to be locked
+ * @proxy_owner:the task to set as owner
+ *
+ * No locking. Caller has to do serializing itself
+ * Special API call for PI-futex support
+ */
+void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
+ struct task_struct *proxy_owner)
+{
+ __rt_mutex_init(lock, NULL);
+ debug_rt_mutex_lock(lock __RET_IP__);
+ rt_mutex_set_owner(lock, proxy_owner, 0);
+ rt_mutex_deadlock_account_lock(lock, proxy_owner);
+}
+
+/**
+ * rt_mutex_proxy_unlock - release a lock on behalf of owner
+ *
+ * @lock: the rt_mutex to be locked
+ *
+ * No locking. Caller has to do serializing itself
+ * Special API call for PI-futex support
+ */
+void rt_mutex_proxy_unlock(struct rt_mutex *lock,
+ struct task_struct *proxy_owner)
+{
+ debug_rt_mutex_proxy_unlock(lock);
+ rt_mutex_set_owner(lock, NULL, 0);
+ rt_mutex_deadlock_account_unlock(proxy_owner);
+}
+
+/**
+ * rt_mutex_next_owner - return the next owner of the lock
+ *
+ * @lock: the rt lock query
+ *
+ * Returns the next owner of the lock or NULL
+ *
+ * Caller has to serialize against other accessors to the lock
+ * itself.
+ *
+ * Special API call for PI-futex support
+ */
+struct task_struct *rt_mutex_next_owner(struct rt_mutex *lock)
+{
+ if (!rt_mutex_has_waiters(lock))
+ return NULL;
+
+ return rt_mutex_top_waiter(lock)->task;
+}
-
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