From dc4564f5dc2d4b11f3f3c8d3ac94012b1c7347d6 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Sun, 15 Aug 2021 23:28:53 +0200
Subject: [PATCH] locking/ww_mutex: Implement rt_mutex accessors

Provide the type defines and the helper inlines for rtmutex based ww_mutexes.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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/20210815211304.790760545@linutronix.de
---
 kernel/locking/ww_mutex.h | 80 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)

diff --git a/kernel/locking/ww_mutex.h b/kernel/locking/ww_mutex.h
index 309f3e4d814a..7da98904b3ea 100644
--- a/kernel/locking/ww_mutex.h
+++ b/kernel/locking/ww_mutex.h
@@ -1,5 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
+#ifndef WW_RT
+
 #define MUTEX		mutex
 #define MUTEX_WAITER	mutex_waiter
 
@@ -83,6 +85,82 @@ static inline void lockdep_assert_wait_lock_held(struct mutex *lock)
 	lockdep_assert_held(&lock->wait_lock);
 }
 
+#else /* WW_RT */
+
+#define MUTEX		rt_mutex
+#define MUTEX_WAITER	rt_mutex_waiter
+
+static inline struct rt_mutex_waiter *
+__ww_waiter_first(struct rt_mutex *lock)
+{
+	struct rb_node *n = rb_first(&lock->rtmutex.waiters.rb_root);
+	if (!n)
+		return NULL;
+	return rb_entry(n, struct rt_mutex_waiter, tree_entry);
+}
+
+static inline struct rt_mutex_waiter *
+__ww_waiter_next(struct rt_mutex *lock, struct rt_mutex_waiter *w)
+{
+	struct rb_node *n = rb_next(&w->tree_entry);
+	if (!n)
+		return NULL;
+	return rb_entry(n, struct rt_mutex_waiter, tree_entry);
+}
+
+static inline struct rt_mutex_waiter *
+__ww_waiter_prev(struct rt_mutex *lock, struct rt_mutex_waiter *w)
+{
+	struct rb_node *n = rb_prev(&w->tree_entry);
+	if (!n)
+		return NULL;
+	return rb_entry(n, struct rt_mutex_waiter, tree_entry);
+}
+
+static inline struct rt_mutex_waiter *
+__ww_waiter_last(struct rt_mutex *lock)
+{
+	struct rb_node *n = rb_last(&lock->rtmutex.waiters.rb_root);
+	if (!n)
+		return NULL;
+	return rb_entry(n, struct rt_mutex_waiter, tree_entry);
+}
+
+static inline void
+__ww_waiter_add(struct rt_mutex *lock, struct rt_mutex_waiter *waiter, struct rt_mutex_waiter *pos)
+{
+	/* RT unconditionally adds the waiter first and then removes it on error */
+}
+
+static inline struct task_struct *
+__ww_mutex_owner(struct rt_mutex *lock)
+{
+	return rt_mutex_owner(&lock->rtmutex);
+}
+
+static inline bool
+__ww_mutex_has_waiters(struct rt_mutex *lock)
+{
+	return rt_mutex_has_waiters(&lock->rtmutex);
+}
+
+static inline void lock_wait_lock(struct rt_mutex *lock)
+{
+	raw_spin_lock(&lock->rtmutex.wait_lock);
+}
+
+static inline void unlock_wait_lock(struct rt_mutex *lock)
+{
+	raw_spin_unlock(&lock->rtmutex.wait_lock);
+}
+
+static inline void lockdep_assert_wait_lock_held(struct rt_mutex *lock)
+{
+	lockdep_assert_held(&lock->rtmutex.wait_lock);
+}
+
+#endif /* WW_RT */
+
 /*
  * Wait-Die:
  *   The newer transactions are killed when:
@@ -169,7 +247,9 @@ __ww_mutex_die(struct MUTEX *lock, struct MUTEX_WAITER *waiter,
 
 	if (waiter->ww_ctx->acquired > 0 &&
 			__ww_ctx_stamp_after(waiter->ww_ctx, ww_ctx)) {
+#ifndef WW_RT
 		debug_mutex_wake_waiter(lock, waiter);
+#endif
 		wake_up_process(waiter->task);
 	}