rust_binder: add `wait_for_work` tracepoint

Add the Rust Binder `wait_for_work` tracepoint declaration and wire
it into the thread read path before selecting the work source.

Signed-off-by: Mohamad Alsadhan <mo@sdhn.cc>
Link: https://patch.msgid.link/20260317-rust-binder-trace-v3-3-6fae4fbcf637@sdhn.cc
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 34 insertions, 2 deletions

diff --git a/drivers/android/binder/rust_binder_events.h b/drivers/android/binder/rust_binder_events.h
index 4fda8576c01f..62b587c7c494 100644
--- a/drivers/android/binder/rust_binder_events.h
+++ b/drivers/android/binder/rust_binder_events.h
@@ -51,6 +51,24 @@ DEFINE_RBINDER_FUNCTION_RETURN_EVENT(binder_ioctl_done);
 DEFINE_RBINDER_FUNCTION_RETURN_EVENT(binder_read_done);
 DEFINE_RBINDER_FUNCTION_RETURN_EVENT(binder_write_done);
 
+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),
+	TP_STRUCT__entry(
+		__field(bool, proc_work)
+		__field(bool, transaction_stack)
+		__field(bool, thread_todo)
+	),
+	TP_fast_assign(
+		__entry->proc_work = proc_work;
+		__entry->transaction_stack = transaction_stack;
+		__entry->thread_todo = thread_todo;
+	),
+	TP_printk("proc_work=%d transaction_stack=%d thread_todo=%d",
+		  __entry->proc_work, __entry->transaction_stack,
+		  __entry->thread_todo)
+);
+
 TRACE_EVENT(binder_transaction,
 	TP_PROTO(bool reply, rust_binder_transaction t, struct task_struct *thread),
 	TP_ARGS(reply, t, thread),
diff --git a/drivers/android/binder/thread.rs b/drivers/android/binder/thread.rs
index 138c45cecfa0..62e293e1a4b8 100644
--- a/drivers/android/binder/thread.rs
+++ b/drivers/android/binder/thread.rs
@@ -1437,11 +1437,18 @@ impl Thread {
             UserSlice::new(UserPtr::from_addr(read_start as _), read_len as _).writer(),
             self,
         );
-        let (in_pool, use_proc_queue) = {
+        let (in_pool, has_transaction, thread_todo, use_proc_queue) = {
             let inner = self.inner.lock();
-            (inner.is_looper(), inner.should_use_process_work_queue())
+            (
+                inner.is_looper(),
+                inner.current_transaction.is_some(),
+                !inner.work_list.is_empty(),
+                inner.should_use_process_work_queue(),
+            )
         };
 
+        crate::trace::trace_wait_for_work(use_proc_queue, has_transaction, thread_todo);
+
         let getter = if use_proc_queue {
             Self::get_work
         } else {
diff --git a/drivers/android/binder/trace.rs b/drivers/android/binder/trace.rs
index 3b0458e2738c..1f62b2276740 100644
--- a/drivers/android/binder/trace.rs
+++ b/drivers/android/binder/trace.rs
@@ -15,6 +15,7 @@ declare_trace! {
     unsafe fn binder_ioctl_done(ret: c_int);
     unsafe fn binder_read_done(ret: c_int);
     unsafe fn binder_write_done(ret: c_int);
+    unsafe fn binder_wait_for_work(proc_work: bool, transaction_stack: bool, thread_todo: bool);
     unsafe fn binder_transaction(reply: bool, t: rust_binder_transaction, thread: *mut task_struct);
 }
 
@@ -54,6 +55,12 @@ pub(crate) fn trace_write_done(ret: Result) {
 }
 
 #[inline]
+pub(crate) fn trace_wait_for_work(proc_work: bool, transaction_stack: bool, thread_todo: bool) {
+    // SAFETY: Always safe to call.
+    unsafe { binder_wait_for_work(proc_work, transaction_stack, thread_todo) }
+}
+
+#[inline]
 pub(crate) fn trace_transaction(reply: bool, t: &Transaction, thread: Option<&Task>) {
     let thread = match thread {
         Some(thread) => thread.as_ptr(),