ANDROID: vendor_hooks: Add hooks for rt_mutex steal

Add hooks at rt_mutex_steal function so that oems can decide
whether tasks with the same priority steal the rt_mutex or
not. We did experiments and found that rt_mutex throughput
can benefit a lot when threads with the same priority can
steal the rt_mutex lock.

Bug: 317670024
Change-Id: Id60a7a41c6c77a67808982d3667946cabe4acc8f
Signed-off-by: xeiliujie <xieliujie@oppo.com>

drivers/android/vendor_hooks.c

@@ -145,6 +145,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_task_blocks_on_rtmutex);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_rtmutex_waiter_prio);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_rtmutex_wait_start);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_rtmutex_wait_finish);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_rt_mutex_steal);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_mutex_opt_spin_start);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_mutex_opt_spin_finish);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_mutex_can_spin_on_owner);

include/trace/hooks/dtask.h

@@ -48,6 +48,9 @@ DECLARE_HOOK(android_vh_rtmutex_wait_start,
 DECLARE_HOOK(android_vh_rtmutex_wait_finish,
 	TP_PROTO(struct rt_mutex_base *lock),
 	TP_ARGS(lock));
+DECLARE_HOOK(android_vh_rt_mutex_steal,
+	TP_PROTO(int waiter_prio, int top_waiter_prio, bool *ret),
+	TP_ARGS(waiter_prio, top_waiter_prio, ret));
 
 DECLARE_HOOK(android_vh_rwsem_read_wait_start,
 	TP_PROTO(struct rw_semaphore *sem),

kernel/locking/rtmutex.c

@@ -389,9 +389,15 @@ static __always_inline int rt_mutex_waiter_equal(struct rt_mutex_waiter *left,
 static inline bool rt_mutex_steal(struct rt_mutex_waiter *waiter,
 				  struct rt_mutex_waiter *top_waiter)
 {
+	bool ret = false;
+
 	if (rt_mutex_waiter_less(waiter, top_waiter))
 		return true;
 
+	trace_android_vh_rt_mutex_steal(waiter->prio, top_waiter->prio, &ret);
+	if (ret)
+		return true;
+
 #ifdef RT_MUTEX_BUILD_SPINLOCKS
 	/*
 	 * Note that RT tasks are excluded from same priority (lateral)