rust_binder: add ioctl/read/write done tracepoints

Add Rust Binder tracepoints declarations for `ioctl_done`,
`read_done` and `write_done`.

Additionally, wire in the new tracepoints into the corresponding
Binder call sites.

Note that the new tracepoints report final errno-style return values,
matching the existing C model for operation completion.

Signed-off-by: Mohamad Alsadhan <mo@sdhn.cc>
Link: https://patch.msgid.link/20260317-rust-binder-trace-v3-2-6fae4fbcf637@sdhn.cc
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/android/binder/process.rs

@@ -1659,11 +1659,14 @@ pub(crate) fn ioctl(this: ArcBorrow<'_, Process>, file: &File, cmd: u32, arg: us
 
         const _IOC_READ_WRITE: u32 = _IOC_READ | _IOC_WRITE;
 
-        match _IOC_DIR(cmd) {
+        let res = match _IOC_DIR(cmd) {
             _IOC_WRITE => Self::ioctl_write_only(this, file, cmd, &mut user_slice.reader()),
             _IOC_READ_WRITE => Self::ioctl_write_read(this, file, cmd, user_slice),
             _ => Err(EINVAL),
-        }
+        };
+
+        crate::trace::trace_ioctl_done(res);
+        res
     }
 
     pub(crate) fn mmap(

drivers/android/binder/rust_binder_events.h

@@ -30,6 +30,27 @@ TRACE_EVENT(binder_ioctl,
 	TP_printk("cmd=0x%x arg=0x%lx", __entry->cmd, __entry->arg)
 );
 
+DECLARE_EVENT_CLASS(binder_function_return_class,
+	TP_PROTO(int ret),
+	TP_ARGS(ret),
+	TP_STRUCT__entry(
+		__field(int, ret)
+	),
+	TP_fast_assign(
+		__entry->ret = ret;
+	),
+	TP_printk("ret=%d", __entry->ret)
+);
+
+#define DEFINE_RBINDER_FUNCTION_RETURN_EVENT(name)	\
+DEFINE_EVENT(binder_function_return_class, name,	\
+	TP_PROTO(int ret), \
+	TP_ARGS(ret))
+
+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_transaction,
 	TP_PROTO(bool reply, rust_binder_transaction t, struct task_struct *thread),
 	TP_ARGS(reply, t, thread),

drivers/android/binder/thread.rs

@@ -1507,6 +1507,7 @@ pub(crate) fn write_read(self: &Arc<Self>, data: UserSlice, wait: bool) -> Resul
         let mut ret = Ok(());
         if req.write_size > 0 {
             ret = self.write(&mut req);
+            crate::trace::trace_write_done(ret);
             if let Err(err) = ret {
                 pr_warn!(
                     "Write failure {:?} in pid:{}",
@@ -1523,6 +1524,7 @@ pub(crate) fn write_read(self: &Arc<Self>, data: UserSlice, wait: bool) -> Resul
         // Go through the work queue.
         if req.read_size > 0 {
             ret = self.read(&mut req, wait);
+            crate::trace::trace_read_done(ret);
             if ret.is_err() && ret != Err(EINTR) {
                 pr_warn!(
                     "Read failure {:?} in pid:{}",

drivers/android/binder/trace.rs

@@ -5,12 +5,16 @@
 use crate::transaction::Transaction;
 
 use kernel::bindings::{rust_binder_transaction, task_struct};
-use kernel::ffi::{c_uint, c_ulong};
+use kernel::error::Result;
+use kernel::ffi::{c_int, c_uint, c_ulong};
 use kernel::task::Task;
 use kernel::tracepoint::declare_trace;
 
 declare_trace! {
     unsafe fn binder_ioctl(cmd: c_uint, arg: c_ulong);
+    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_transaction(reply: bool, t: rust_binder_transaction, thread: *mut task_struct);
 }
 
@@ -19,12 +23,36 @@ fn raw_transaction(t: &Transaction) -> rust_binder_transaction {
     t as *const Transaction as rust_binder_transaction
 }
 
+#[inline]
+fn to_errno(ret: Result) -> i32 {
+    match ret {
+        Ok(()) => 0,
+        Err(err) => err.to_errno(),
+    }
+}
+
 #[inline]
 pub(crate) fn trace_ioctl(cmd: u32, arg: usize) {
     // SAFETY: Always safe to call.
     unsafe { binder_ioctl(cmd, arg as c_ulong) }
 }
 
+#[inline]
+pub(crate) fn trace_ioctl_done(ret: Result) {
+    // SAFETY: Always safe to call.
+    unsafe { binder_ioctl_done(to_errno(ret)) }
+}
+#[inline]
+pub(crate) fn trace_read_done(ret: Result) {
+    // SAFETY: Always safe to call.
+    unsafe { binder_read_done(to_errno(ret)) }
+}
+#[inline]
+pub(crate) fn trace_write_done(ret: Result) {
+    // SAFETY: Always safe to call.
+    unsafe { binder_write_done(to_errno(ret)) }
+}
+
 #[inline]
 pub(crate) fn trace_transaction(reply: bool, t: &Transaction, thread: Option<&Task>) {
     let thread = match thread {