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[4.4,03/11] futex,rt_mutex: Introduce rt_mutex_init_waiter()

Message ID 20210802134624.1934-4-thunder.leizhen@huawei.com
State New
Headers show
Series Fix a potential infinite loop in RT futex-pi scenarios | expand

Commit Message

Leizhen (ThunderTown) Aug. 2, 2021, 1:46 p.m. UTC 
From: Peter Zijlstra <peterz@infradead.org>


[ Upstream commit 50809358dd7199aa7ce232f6877dd09ec30ef374 ]

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>

Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>

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

-- 
2.26.0.106.g9fadedd
diff mbox series

Patch

diff --git a/kernel/futex.c b/kernel/futex.c
index dab9c79a931a23e..53a085a378f3844 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -3156,10 +3156,7 @@  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 1c0cb5c3c6ad6fe..fa24df4bc7a8ff0 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1155,6 +1155,14 @@  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
@@ -1236,9 +1244,7 @@  rt_mutex_slowlock(struct rt_mutex *lock, int state,
 	struct rt_mutex_waiter waiter;
 	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);
 
 	raw_spin_lock(&lock->wait_lock);
 
diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h
index 4584db96265d429..0424ff97bb69cad 100644
--- a/kernel/locking/rtmutex_common.h
+++ b/kernel/locking/rtmutex_common.h
@@ -102,6 +102,7 @@  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);
+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);