locking/ww_mutex: Abstract out internal lock accesses

Accessing the internal wait_lock of mutex and rtmutex is slightly
different. Provide helper functions for that.
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/20210815211304.734635961@linutronix.de

include/linux/ww_mutex.h

@@ -19,6 +19,11 @@
 
 #include <linux/mutex.h>
 
+#define WW_MUTEX_BASE			mutex
+#define ww_mutex_base_init(l,n,k)	__mutex_init(l,n,k)
+#define ww_mutex_base_trylock(l)	mutex_trylock(l)
+#define ww_mutex_base_is_locked(b)	mutex_is_locked((b))
+
 struct ww_class {
 	atomic_long_t stamp;
 	struct lock_class_key acquire_key;
@@ -29,7 +34,7 @@ struct ww_class {
 };
 
 struct ww_mutex {
-	struct mutex base;
+	struct WW_MUTEX_BASE base;
 	struct ww_acquire_ctx *ctx;
 #ifdef CONFIG_DEBUG_MUTEXES
 	struct ww_class *ww_class;
@@ -82,7 +87,7 @@ struct ww_acquire_ctx {
 static inline void ww_mutex_init(struct ww_mutex *lock,
 				 struct ww_class *ww_class)
 {
-	__mutex_init(&lock->base, ww_class->mutex_name, &ww_class->mutex_key);
+	ww_mutex_base_init(&lock->base, ww_class->mutex_name, &ww_class->mutex_key);
 	lock->ctx = NULL;
 #ifdef CONFIG_DEBUG_MUTEXES
 	lock->ww_class = ww_class;
@@ -330,7 +335,7 @@ extern void ww_mutex_unlock(struct ww_mutex *lock);
  */
 static inline int __must_check ww_mutex_trylock(struct ww_mutex *lock)
 {
-	return mutex_trylock(&lock->base);
+	return ww_mutex_base_trylock(&lock->base);
 }
 
 /***
@@ -354,7 +359,7 @@ static inline void ww_mutex_destroy(struct ww_mutex *lock)
  */
 static inline bool ww_mutex_is_locked(struct ww_mutex *lock)
 {
-	return mutex_is_locked(&lock->base);
+	return ww_mutex_base_is_locked(&lock->base);
 }
 
 #endif

kernel/locking/ww_mutex.h

@@ -68,6 +68,21 @@ __ww_mutex_has_waiters(struct mutex *lock)
 	return atomic_long_read(&lock->owner) & MUTEX_FLAG_WAITERS;
 }
 
+static inline void lock_wait_lock(struct mutex *lock)
+{
+	raw_spin_lock(&lock->wait_lock);
+}
+
+static inline void unlock_wait_lock(struct mutex *lock)
+{
+	raw_spin_unlock(&lock->wait_lock);
+}
+
+static inline void lockdep_assert_wait_lock_held(struct mutex *lock)
+{
+	lockdep_assert_held(&lock->wait_lock);
+}
+
 /*
  * Wait-Die:
  *   The newer transactions are killed when:
@@ -174,7 +189,7 @@ static bool __ww_mutex_wound(struct MUTEX *lock,
 {
 	struct task_struct *owner = __ww_mutex_owner(lock);
 
-	lockdep_assert_held(&lock->wait_lock);
+	lockdep_assert_wait_lock_held(lock);
 
 	/*
 	 * Possible through __ww_mutex_add_waiter() when we race with
@@ -227,7 +242,7 @@ __ww_mutex_check_waiters(struct MUTEX *lock, struct ww_acquire_ctx *ww_ctx)
 {
 	struct MUTEX_WAITER *cur;
 
-	lockdep_assert_held(&lock->wait_lock);
+	lockdep_assert_wait_lock_held(lock);
 
 	for (cur = __ww_waiter_first(lock); cur;
 	     cur = __ww_waiter_next(lock, cur)) {
@@ -275,9 +290,9 @@ ww_mutex_set_context_fastpath(struct ww_mutex *lock, struct ww_acquire_ctx *ctx)
 	 * Uh oh, we raced in fastpath, check if any of the waiters need to
 	 * die or wound us.
 	 */
-	raw_spin_lock(&lock->base.wait_lock);
+	lock_wait_lock(&lock->base);
 	__ww_mutex_check_waiters(&lock->base, ctx);
-	raw_spin_unlock(&lock->base.wait_lock);
+	unlock_wait_lock(&lock->base);
 }
 
 static __always_inline int