rt_mutex: Add lockdep annotations

Now that (PI) futexes have their own private RT-mutex interface and
implementation we can easily add lockdep annotations to the existing
RT-mutex interface.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

6 files changed, 60 insertions, 14 deletions

diff --git a/include/linux/rtmutex.h b/include/linux/rtmutex.h
index 1abba5ce2a2f..44fd002f7cd5 100644
--- a/include/linux/rtmutex.h
+++ b/include/linux/rtmutex.h
@@ -37,6 +37,9 @@ struct rt_mutex {
         int                     line;
         void                    *magic;
 #endif
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        struct lockdep_map      dep_map;
+#endif
 };
 
 struct rt_mutex_waiter;
@@ -58,19 +61,33 @@ struct hrtimer_sleeper;
 #ifdef CONFIG_DEBUG_RT_MUTEXES
 # define __DEBUG_RT_MUTEX_INITIALIZER(mutexname) \
         , .name = #mutexname, .file = __FILE__, .line = __LINE__
-# define rt_mutex_init(mutex)                   __rt_mutex_init(mutex, __func__)
+
+# define rt_mutex_init(mutex) \
+do { \
+        static struct lock_class_key __key; \
+        __rt_mutex_init(mutex, __func__, &__key); \
+} while (0)
+
  extern void rt_mutex_debug_task_free(struct task_struct *tsk);
 #else
 # define __DEBUG_RT_MUTEX_INITIALIZER(mutexname)
-# define rt_mutex_init(mutex)                   __rt_mutex_init(mutex, NULL)
+# define rt_mutex_init(mutex)                   __rt_mutex_init(mutex, NULL, NULL)
 # define rt_mutex_debug_task_free(t)                    do { } while (0)
 #endif
 
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+#define __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname) \
+        , .dep_map = { .name = #mutexname }
+#else
+#define __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname)
+#endif
+
 #define __RT_MUTEX_INITIALIZER(mutexname) \
         { .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(mutexname.wait_lock) \
         , .waiters = RB_ROOT \
         , .owner = NULL \
-        __DEBUG_RT_MUTEX_INITIALIZER(mutexname)}
+        __DEBUG_RT_MUTEX_INITIALIZER(mutexname) \
+        __DEP_MAP_RT_MUTEX_INITIALIZER(mutexname)}
 
 #define DEFINE_RT_MUTEX(mutexname) \
         struct rt_mutex mutexname = __RT_MUTEX_INITIALIZER(mutexname)
@@ -86,7 +103,7 @@ static inline int rt_mutex_is_locked(struct rt_mutex *lock)
         return lock->owner != NULL;
 }
 
-extern void __rt_mutex_init(struct rt_mutex *lock, const char *name);
+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);
 
 extern void rt_mutex_lock(struct rt_mutex *lock);
diff --git a/kernel/locking/rtmutex-debug.c b/kernel/locking/rtmutex-debug.c
index 58e366ad36f4..ac35e648b0e5 100644
--- a/kernel/locking/rtmutex-debug.c
+++ b/kernel/locking/rtmutex-debug.c
@@ -166,12 +166,16 @@ void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter)
         memset(waiter, 0x22, sizeof(*waiter));
 }
 
-void debug_rt_mutex_init(struct rt_mutex *lock, const char *name)
+void debug_rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key)
 {
         /*
          * Make sure we are not reinitializing a held lock:
          */
         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
         lock->name = name;
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+        lockdep_init_map(&lock->dep_map, name, key, 0);
+#endif
 }
 
diff --git a/kernel/locking/rtmutex-debug.h b/kernel/locking/rtmutex-debug.h
index b585af9a1b50..5078c6ddf4a5 100644
--- a/kernel/locking/rtmutex-debug.h
+++ b/kernel/locking/rtmutex-debug.h
@@ -11,7 +11,7 @@
 
 extern void debug_rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
 extern void debug_rt_mutex_free_waiter(struct rt_mutex_waiter *waiter);
-extern void debug_rt_mutex_init(struct rt_mutex *lock, const char *name);
+extern void debug_rt_mutex_init(struct rt_mutex *lock, const char *name, struct lock_class_key *key);
 extern void debug_rt_mutex_lock(struct rt_mutex *lock);
 extern void debug_rt_mutex_unlock(struct rt_mutex *lock);
 extern void debug_rt_mutex_proxy_lock(struct rt_mutex *lock,
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 28cd09e635ed..43123533e9b1 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1481,6 +1481,7 @@ 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);
 }
 EXPORT_SYMBOL_GPL(rt_mutex_lock);
@@ -1496,9 +1497,16 @@ EXPORT_SYMBOL_GPL(rt_mutex_lock);
  */
 int __sched rt_mutex_lock_interruptible(struct rt_mutex *lock)
 {
+        int ret;
+
         might_sleep();
 
-        return rt_mutex_fastlock(lock, TASK_INTERRUPTIBLE, rt_mutex_slowlock);
+        mutex_acquire(&lock->dep_map, 0, 0, _RET_IP_);
+        ret = rt_mutex_fastlock(lock, TASK_INTERRUPTIBLE, rt_mutex_slowlock);
+        if (ret)
+                mutex_release(&lock->dep_map, 1, _RET_IP_);
+
+        return ret;
 }
 EXPORT_SYMBOL_GPL(rt_mutex_lock_interruptible);
 
@@ -1526,11 +1534,18 @@ int __sched rt_mutex_futex_trylock(struct rt_mutex *lock)
 int
 rt_mutex_timed_lock(struct rt_mutex *lock, struct hrtimer_sleeper *timeout)
 {
+        int ret;
+
         might_sleep();
 
-        return rt_mutex_timed_fastlock(lock, TASK_INTERRUPTIBLE, timeout,
+        mutex_acquire(&lock->dep_map, 0, 0, _RET_IP_);
+        ret = rt_mutex_timed_fastlock(lock, TASK_INTERRUPTIBLE, timeout,
                                        RT_MUTEX_MIN_CHAINWALK,
                                        rt_mutex_slowlock);
+        if (ret)
+                mutex_release(&lock->dep_map, 1, _RET_IP_);
+
+        return ret;
 }
 EXPORT_SYMBOL_GPL(rt_mutex_timed_lock);
 
@@ -1547,10 +1562,16 @@ EXPORT_SYMBOL_GPL(rt_mutex_timed_lock);
  */
 int __sched rt_mutex_trylock(struct rt_mutex *lock)
 {
+        int ret;
+
         if (WARN_ON_ONCE(in_irq() || in_nmi() || in_serving_softirq()))
                 return 0;
 
-        return rt_mutex_fasttrylock(lock, rt_mutex_slowtrylock);
+        ret = rt_mutex_fasttrylock(lock, rt_mutex_slowtrylock);
+        if (ret)
+                mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);
+
+        return ret;
 }
 EXPORT_SYMBOL_GPL(rt_mutex_trylock);
 
@@ -1561,6 +1582,7 @@ EXPORT_SYMBOL_GPL(rt_mutex_trylock);
  */
 void __sched rt_mutex_unlock(struct rt_mutex *lock)
 {
+        mutex_release(&lock->dep_map, 1, _RET_IP_);
         rt_mutex_fastunlock(lock, rt_mutex_slowunlock);
 }
 EXPORT_SYMBOL_GPL(rt_mutex_unlock);
@@ -1620,7 +1642,6 @@ void rt_mutex_destroy(struct rt_mutex *lock)
         lock->magic = NULL;
 #endif
 }
-
 EXPORT_SYMBOL_GPL(rt_mutex_destroy);
 
 /**
@@ -1632,14 +1653,15 @@ EXPORT_SYMBOL_GPL(rt_mutex_destroy);
  *
  * Initializing of a locked rt lock is not allowed
  */
-void __rt_mutex_init(struct rt_mutex *lock, const char *name)
+void __rt_mutex_init(struct rt_mutex *lock, const char *name,
+                     struct lock_class_key *key)
 {
         lock->owner = NULL;
         raw_spin_lock_init(&lock->wait_lock);
         lock->waiters = RB_ROOT;
         lock->waiters_leftmost = NULL;
 
-        debug_rt_mutex_init(lock, name);
+        debug_rt_mutex_init(lock, name, key);
 }
 EXPORT_SYMBOL_GPL(__rt_mutex_init);
 
@@ -1660,7 +1682,7 @@ EXPORT_SYMBOL_GPL(__rt_mutex_init);
 void rt_mutex_init_proxy_locked(struct rt_mutex *lock,
                                 struct task_struct *proxy_owner)
 {
-        __rt_mutex_init(lock, NULL);
+        __rt_mutex_init(lock, NULL, NULL);
         debug_rt_mutex_proxy_lock(lock, proxy_owner);
         rt_mutex_set_owner(lock, proxy_owner);
 }
diff --git a/kernel/locking/rtmutex.h b/kernel/locking/rtmutex.h
index 6607802efa8b..5c253caffe91 100644
--- a/kernel/locking/rtmutex.h
+++ b/kernel/locking/rtmutex.h
@@ -17,7 +17,7 @@
 #define debug_rt_mutex_proxy_lock(l,p)                  do { } while (0)
 #define debug_rt_mutex_proxy_unlock(l)                  do { } while (0)
 #define debug_rt_mutex_unlock(l)                        do { } while (0)
-#define debug_rt_mutex_init(m, n)                       do { } while (0)
+#define debug_rt_mutex_init(m, n, k)                    do { } while (0)
 #define debug_rt_mutex_deadlock(d, a ,l)                do { } while (0)
 #define debug_rt_mutex_print_deadlock(w)                do { } while (0)
 #define debug_rt_mutex_reset_waiter(w)                  do { } while (0)
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index e4587ebe52c7..ca615129aec5 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1052,6 +1052,7 @@ config DEBUG_LOCK_ALLOC
         depends on DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT
         select DEBUG_SPINLOCK
         select DEBUG_MUTEXES
+        select DEBUG_RT_MUTEXES if RT_MUTEXES
         select LOCKDEP
         help
          This feature will check whether any held lock (spinlock, rwlock,
@@ -1067,6 +1068,7 @@ config PROVE_LOCKING
         select LOCKDEP
         select DEBUG_SPINLOCK
         select DEBUG_MUTEXES
+        select DEBUG_RT_MUTEXES if RT_MUTEXES
         select DEBUG_LOCK_ALLOC
         select TRACE_IRQFLAGS
         default n
@@ -1121,6 +1123,7 @@ config LOCK_STAT
         select LOCKDEP
         select DEBUG_SPINLOCK
         select DEBUG_MUTEXES
+        select DEBUG_RT_MUTEXES if RT_MUTEXES
         select DEBUG_LOCK_ALLOC
         default n
         help