[PATCH v4 1/2] rtmutex: allow specifying a subclass for nested locking

From: Peter Rosin <peda@axentia.se>
To: linux-kernel@vger.kernel.org
Cc: Peter Rosin <peda@axentia.se>, Wolfram Sang <wsa@the-dreams.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>,
	Davidlohr Bueso <dave@stgolabs.net>,
	Philippe Ombredanne <pombredanne@nexb.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-i2c@vger.kernel.org, Peter Chang <dpf@google.com>,
	Deepa Dinamani <deepadinamani@google.com>,
	John Sperbeck <jsperbeck@google.com>
Subject: [PATCH v4 1/2] rtmutex: allow specifying a subclass for nested locking
Date: Fri, 20 Jul 2018 10:39:13 +0200	[thread overview]
Message-ID: <20180720083914.1950-2-peda@axentia.se> (raw)
In-Reply-To: <20180720083914.1950-1-peda@axentia.se>

Needed for annotating rt_mutex locks.

Tested-by: John Sperbeck <jsperbeck@google.com>
Signed-off-by: Peter Rosin <peda@axentia.se>
---
 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
-- 
2.11.0

