[tip:locking/core] futex,rt_mutex: Introduce rt_mutex_init_waiter()

[tip-bot for Peter Zijlstra <tipbot@zytor.com>]

Commit-ID:  50809358dd7199aa7ce232f6877dd09ec30ef374
Gitweb:     http://git.kernel.org/tip/50809358dd7199aa7ce232f6877dd09ec30ef374
Author:     Peter Zijlstra <peterz@infradead.org>
AuthorDate: Wed, 22 Mar 2017 11:35:56 +0100
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Thu, 23 Mar 2017 19:10:09 +0100

futex,rt_mutex: Introduce rt_mutex_init_waiter()

Since there's already two copies of this code, introduce a helper now
before adding a third one.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: juri.lelli@arm.com
Cc: bigeasy@linutronix.de
Cc: xlpang@redhat.com
Cc: rostedt@goodmis.org
Cc: mathieu.desnoyers@efficios.com
Cc: jdesfossez@efficios.com
Cc: dvhart@infradead.org
Cc: bristot@redhat.com
Link: http://lkml.kernel.org/r/20170322104151.950039479@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

---
 kernel/futex.c                  |  5 +----
 kernel/locking/rtmutex.c        | 12 +++++++++---
 kernel/locking/rtmutex_common.h |  1 +
 3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/kernel/futex.c b/kernel/futex.c
index 3b0aace..f03ff63 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2956,10 +2956,7 @@ static int futex_wait_requeue_pi(u32 __user *uaddr, unsigned int flags,
 	 * The waiter is allocated on our stack, manipulated by the requeue
 	 * code while we sleep on uaddr.
 	 */
-	debug_rt_mutex_init_waiter(&rt_waiter);
-	RB_CLEAR_NODE(&rt_waiter.pi_tree_entry);
-	RB_CLEAR_NODE(&rt_waiter.tree_entry);
-	rt_waiter.task = NULL;
+	rt_mutex_init_waiter(&rt_waiter);
 
 	ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, VERIFY_WRITE);
 	if (unlikely(ret != 0))
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 7d63bc5..d2fe4b4 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1153,6 +1153,14 @@ void rt_mutex_adjust_pi(struct task_struct *task)
 				   next_lock, NULL, task);
 }
 
+void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
+{
+	debug_rt_mutex_init_waiter(waiter);
+	RB_CLEAR_NODE(&waiter->pi_tree_entry);
+	RB_CLEAR_NODE(&waiter->tree_entry);
+	waiter->task = NULL;
+}
+
 /**
  * __rt_mutex_slowlock() - Perform the wait-wake-try-to-take loop
  * @lock:		 the rt_mutex to take
@@ -1235,9 +1243,7 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state,
 	unsigned long flags;
 	int ret = 0;
 
-	debug_rt_mutex_init_waiter(&waiter);
-	RB_CLEAR_NODE(&waiter.pi_tree_entry);
-	RB_CLEAR_NODE(&waiter.tree_entry);
+	rt_mutex_init_waiter(&waiter);
 
 	/*
 	 * Technically we could use raw_spin_[un]lock_irq() here, but this can
diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h
index af667f6..10f57d6 100644
--- a/kernel/locking/rtmutex_common.h
+++ b/kernel/locking/rtmutex_common.h
@@ -103,6 +103,7 @@ 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);
+extern void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
 extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
 				     struct rt_mutex_waiter *waiter,
 				     struct task_struct *task);