linux-kernel - [tip:locking/urgent] locking/rtmutex: Allow specifying a subclass for nested locking

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Date:   Wed, 25 Jul 2018 07:18:59 -0700
From:   tip-bot for Peter Rosin <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     tglx@...utronix.de, linux-kernel@...r.kernel.org, peda@...ntia.se,
        mingo@...nel.org, gregkh@...uxfoundation.org, will.deacon@....com,
        wsa@...-dreams.de, deepadinamani@...gle.com, dave@...olabs.net,
        peterz@...radead.org, torvalds@...ux-foundation.org,
        jsperbeck@...gle.com, hpa@...or.com, dpf@...gle.com,
        pombredanne@...b.com
Subject: [tip:locking/urgent] locking/rtmutex: Allow specifying a subclass
 for nested locking

Commit-ID:  62cedf3e60af03e47849fe2bd6a03ec179422a8a
Gitweb:     https://git.kernel.org/tip/62cedf3e60af03e47849fe2bd6a03ec179422a8a
Author:     Peter Rosin <peda@...ntia.se>
AuthorDate: Fri, 20 Jul 2018 10:39:13 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 25 Jul 2018 11:22:19 +0200

locking/rtmutex: Allow specifying a subclass for nested locking

Needed for annotating rt_mutex locks.

Tested-by: John Sperbeck <jsperbeck@...gle.com>
Signed-off-by: Peter Rosin <peda@...ntia.se>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Davidlohr Bueso <dave@...olabs.net>
Cc: Deepa Dinamani <deepadinamani@...gle.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Chang <dpf@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Philippe Ombredanne <pombredanne@...b.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Will Deacon <will.deacon@....com>
Cc: Wolfram Sang <wsa@...-dreams.de>
Link: http://lkml.kernel.org/r/20180720083914.1950-2-peda@axentia.se
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 include/linux/rtmutex.h  |  7 +++++++
 kernel/locking/rtmutex.c | 29 +++++++++++++++++++++++++----
 2 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/include/linux/rtmutex.h b/include/linux/rtmutex.h
index 1b92a28dd672..6fd615a0eea9 100644
--- a/include/linux/rtmutex.h
+++ b/include/linux/rtmutex.h
@@ -106,7 +106,14 @@ static inline int rt_mutex_is_locked(struct rt_mutex *lock)
 extern void __rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key);
 extern void rt_mutex_destroy(struct rt_mutex *lock);
 
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+extern void rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass);
+#define rt_mutex_lock(lock) rt_mutex_lock_nested(lock, 0)
+#else
 extern void rt_mutex_lock(struct rt_mutex *lock);
+#define rt_mutex_lock_nested(lock, subclass) rt_mutex_lock(lock)
+#endif
+
 extern int rt_mutex_lock_interruptible(struct rt_mutex *lock);
 extern int rt_mutex_timed_lock(struct rt_mutex *lock,
 			       struct hrtimer_sleeper *timeout);
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 4f014be7a4b8..2823d4163a37 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1465,6 +1465,29 @@ rt_mutex_fastunlock(struct rt_mutex *lock,
 		rt_mutex_postunlock(&wake_q);
 }
 
+static inline void __rt_mutex_lock(struct rt_mutex *lock, unsigned int subclass)
+{
+	might_sleep();
+
+	mutex_acquire(&lock->dep_map, subclass, 0, _RET_IP_);
+	rt_mutex_fastlock(lock, TASK_UNINTERRUPTIBLE, rt_mutex_slowlock);
+}
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+/**
+ * rt_mutex_lock_nested - lock a rt_mutex
+ *
+ * @lock: the rt_mutex to be locked
+ * @subclass: the lockdep subclass
+ */
+void __sched rt_mutex_lock_nested(struct rt_mutex *lock, unsigned int subclass)
+{
+	__rt_mutex_lock(lock, subclass);
+}
+EXPORT_SYMBOL_GPL(rt_mutex_lock_nested);
+#endif
+
+#ifndef CONFIG_DEBUG_LOCK_ALLOC
 /**
  * rt_mutex_lock - lock a rt_mutex
  *
@@ -1472,12 +1495,10 @@ rt_mutex_fastunlock(struct rt_mutex *lock,
  */
 void __sched rt_mutex_lock(struct rt_mutex *lock)
 {
-	might_sleep();
-
-	mutex_acquire(&lock->dep_map, 0, 0, _RET_IP_);
-	rt_mutex_fastlock(lock, TASK_UNINTERRUPTIBLE, rt_mutex_slowlock);
+	__rt_mutex_lock(lock, 0);
 }
 EXPORT_SYMBOL_GPL(rt_mutex_lock);
+#endif
 
 /**
  * rt_mutex_lock_interruptible - lock a rt_mutex interruptible