From bb630f9f7a7d43869e4e7f5e4c002207396aea59 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Sun, 15 Aug 2021 23:29:01 +0200
Subject: locking/rtmutex: Add mutex variant for RT

Add the necessary defines, helpers and API functions for replacing struct mutex on
a PREEMPT_RT enabled kernel with an rtmutex based variant.

No functional change when CONFIG_PREEMPT_RT=n

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210815211305.081517417@linutronix.de
---
 include/linux/mutex.h | 66 +++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 56 insertions(+), 10 deletions(-)

(limited to 'include/linux/mutex.h')

diff --git a/include/linux/mutex.h b/include/linux/mutex.h
index 0bbc872ba72b..8f226d460f51 100644
--- a/include/linux/mutex.h
+++ b/include/linux/mutex.h
@@ -20,6 +20,18 @@
 #include <linux/osq_lock.h>
 #include <linux/debug_locks.h>
 
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+# define __DEP_MAP_MUTEX_INITIALIZER(lockname)			\
+		, .dep_map = {					\
+			.name = #lockname,			\
+			.wait_type_inner = LD_WAIT_SLEEP,	\
+		}
+#else
+# define __DEP_MAP_MUTEX_INITIALIZER(lockname)
+#endif
+
+#ifndef CONFIG_PREEMPT_RT
+
 /*
  * Simple, straightforward mutexes with strict semantics:
  *
@@ -93,16 +105,6 @@ do {									\
 	__mutex_init((mutex), #mutex, &__key);				\
 } while (0)
 
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
-# define __DEP_MAP_MUTEX_INITIALIZER(lockname)			\
-		, .dep_map = {					\
-			.name = #lockname,			\
-			.wait_type_inner = LD_WAIT_SLEEP,	\
-		}
-#else
-# define __DEP_MAP_MUTEX_INITIALIZER(lockname)
-#endif
-
 #define __MUTEX_INITIALIZER(lockname) \
 		{ .owner = ATOMIC_LONG_INIT(0) \
 		, .wait_lock = __RAW_SPIN_LOCK_UNLOCKED(lockname.wait_lock) \
@@ -124,6 +126,50 @@ extern void __mutex_init(struct mutex *lock, const char *name,
  */
 extern bool mutex_is_locked(struct mutex *lock);
 
+#else /* !CONFIG_PREEMPT_RT */
+/*
+ * Preempt-RT variant based on rtmutexes.
+ */
+#include <linux/rtmutex.h>
+
+struct mutex {
+	struct rt_mutex_base	rtmutex;
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+	struct lockdep_map	dep_map;
+#endif
+};
+
+#define __MUTEX_INITIALIZER(mutexname)					\
+{									\
+	.rtmutex = __RT_MUTEX_BASE_INITIALIZER(mutexname.rtmutex)	\
+	__DEP_MAP_MUTEX_INITIALIZER(mutexname)				\
+}
+
+#define DEFINE_MUTEX(mutexname)						\
+	struct mutex mutexname = __MUTEX_INITIALIZER(mutexname)
+
+extern void __mutex_rt_init(struct mutex *lock, const char *name,
+			    struct lock_class_key *key);
+extern int mutex_trylock(struct mutex *lock);
+
+static inline void mutex_destroy(struct mutex *lock) { }
+
+#define mutex_is_locked(l)	rt_mutex_base_is_locked(&(l)->rtmutex)
+
+#define __mutex_init(mutex, name, key)			\
+do {							\
+	rt_mutex_base_init(&(mutex)->rtmutex);		\
+	__mutex_rt_init((mutex), name, key);		\
+} while (0)
+
+#define mutex_init(mutex)				\
+do {							\
+	static struct lock_class_key __key;		\
+							\
+	__mutex_init((mutex), #mutex, &__key);		\
+} while (0)
+#endif /* CONFIG_PREEMPT_RT */
+
 /*
  * See kernel/locking/mutex.c for detailed documentation of these APIs.
  * Also see Documentation/locking/mutex-design.rst.
-- 
cgit