linux-kernel - [PATCH v2] rtmutex_api: provide correct extern functions

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Message-ID: <20250531060756.130554-1-pbonzini@redhat.com>
Date: Sat, 31 May 2025 02:07:56 -0400
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org
Cc: mlevitsk@...hat.com,
	Randy Dunlap <rdunlap@...radead.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: [PATCH v2] rtmutex_api: provide correct extern functions

Commit fb49f07ba1d9 ("locking/mutex: implement mutex_lock_killable_nest_lock")
changed the set of functions that mutex.c defines when CONFIG_DEBUG_LOCK_ALLOC
is set.

- it removed the "extern" declaration of mutex_lock_killable_nested from
  include/linux/mutex.h, and replaced it with a macro since it could be
  treated as a special case of _mutex_lock_killable.  It also removed a
  definition of the function in kernel/locking/mutex.c.

- likewise, it replaced mutex_trylock() with the more generic
  mutex_trylock_nest_lock() and replaced mutex_trylock() with a macro.

However, it left the old definitions in place in kernel/locking/rtmutex_api.c,
which causes failures when building with CONFIG_RT_MUTEXES=y.  Bring over
the changes.

Fixes: fb49f07ba1d9 ("locking/mutex: implement mutex_lock_killable_nest_lock")
Reported-by: Randy Dunlap <rdunlap@...radead.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
	This time, with brain connected.

 kernel/locking/rtmutex_api.c | 33 +++++++++++++++++++++------------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/kernel/locking/rtmutex_api.c b/kernel/locking/rtmutex_api.c
index 191e4720e546..f21e59a0525e 100644
--- a/kernel/locking/rtmutex_api.c
+++ b/kernel/locking/rtmutex_api.c
@@ -544,12 +544,12 @@ int __sched mutex_lock_interruptible_nested(struct mutex *lock,
 }
 EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested);
 
-int __sched mutex_lock_killable_nested(struct mutex *lock,
-					    unsigned int subclass)
+int __sched _mutex_lock_killable(struct mutex *lock, unsigned int subclass,
+				 struct lockdep_map *nest_lock)
 {
-	return __mutex_lock_common(lock, TASK_KILLABLE, subclass, NULL, _RET_IP_);
+	return __mutex_lock_common(lock, TASK_KILLABLE, subclass, nest_lock, _RET_IP_);
 }
-EXPORT_SYMBOL_GPL(mutex_lock_killable_nested);
+EXPORT_SYMBOL_GPL(_mutex_lock_killable);
 
 void __sched mutex_lock_io_nested(struct mutex *lock, unsigned int subclass)
 {
@@ -563,6 +563,21 @@ void __sched mutex_lock_io_nested(struct mutex *lock, unsigned int subclass)
 }
 EXPORT_SYMBOL_GPL(mutex_lock_io_nested);
 
+int __sched _mutex_trylock_nest_lock(struct mutex *lock,
+				     struct lockdep_map *nest_lock)
+{
+	int ret;
+
+	if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES) && WARN_ON_ONCE(!in_task()))
+		return 0;
+
+	ret = __rt_mutex_trylock(&lock->rtmutex);
+	if (ret)
+		mutex_acquire_nest(&lock->dep_map, 0, 1, nest_lock, _RET_IP_);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(_mutex_trylock_nest_lock);
 #else /* CONFIG_DEBUG_LOCK_ALLOC */
 
 void __sched mutex_lock(struct mutex *lock)
@@ -591,22 +606,16 @@ void __sched mutex_lock_io(struct mutex *lock)
 	io_schedule_finish(token);
 }
 EXPORT_SYMBOL(mutex_lock_io);
-#endif /* !CONFIG_DEBUG_LOCK_ALLOC */
 
 int __sched mutex_trylock(struct mutex *lock)
 {
-	int ret;
-
 	if (IS_ENABLED(CONFIG_DEBUG_RT_MUTEXES) && WARN_ON_ONCE(!in_task()))
 		return 0;
 
-	ret = __rt_mutex_trylock(&lock->rtmutex);
-	if (ret)
-		mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);
-
-	return ret;
+	return __rt_mutex_trylock(&lock->rtmutex);
 }
 EXPORT_SYMBOL(mutex_trylock);
+#endif /* !CONFIG_DEBUG_LOCK_ALLOC */
 
 void __sched mutex_unlock(struct mutex *lock)
 {
-- 
2.43.5