ANDROID: binder: Add tracing for binder priority inheritance.

Bug: 34461621
Change-Id: I5ebb1c0c49fd42a89ee250a1d70221f767c82c7c
Signed-off-by: Martijn Coenen <maco@google.com>

Author: Martijn Coenen

drivers/android/binder.c

@@ -1154,6 +1154,10 @@ static void binder_do_set_priority(struct task_struct *task,
 			      task->pid, desired.prio,
 			      to_kernel_prio(policy, priority));
 
+	trace_binder_set_priority(task->tgid, task->pid, task->normal_prio,
+				  to_kernel_prio(policy, priority),
+				  desired.prio);
+
 	/* Set the actual priority */
 	if (task->policy != policy || is_rt_policy(policy)) {
 		struct sched_param params;

drivers/android/binder_trace.h

@@ -85,6 +85,30 @@ DEFINE_BINDER_FUNCTION_RETURN_EVENT(binder_ioctl_done);
 DEFINE_BINDER_FUNCTION_RETURN_EVENT(binder_write_done);
 DEFINE_BINDER_FUNCTION_RETURN_EVENT(binder_read_done);
 
+TRACE_EVENT(binder_set_priority,
+	TP_PROTO(int proc, int thread, unsigned int old_prio,
+		 unsigned int desired_prio, unsigned int new_prio),
+	TP_ARGS(proc, thread, old_prio, new_prio, desired_prio),
+
+	TP_STRUCT__entry(
+		__field(int, proc)
+		__field(int, thread)
+		__field(unsigned int, old_prio)
+		__field(unsigned int, new_prio)
+		__field(unsigned int, desired_prio)
+	),
+	TP_fast_assign(
+		__entry->proc = proc;
+		__entry->thread = thread;
+		__entry->old_prio = old_prio;
+		__entry->new_prio = new_prio;
+		__entry->desired_prio = desired_prio;
+	),
+	TP_printk("proc=%d thread=%d old=%d => new=%d desired=%d",
+		  __entry->proc, __entry->thread, __entry->old_prio,
+		  __entry->new_prio, __entry->desired_prio)
+);
+
 TRACE_EVENT(binder_wait_for_work,
 	TP_PROTO(bool proc_work, bool transaction_stack, bool thread_todo),
 	TP_ARGS(proc_work, transaction_stack, thread_todo),