[PATCH 7/7] rust_binder: Implement the BINDER_DEBUG_DEAD_TRANSACTION logging mask to trace in-flight cancellations during teardown

[Jahnavi MN via B4 Relay <devnull+jahnavimn.google.com@kernel.org>]

From: Jahnavi MN <jahnavimn@google.com>

This adds dynamic debug logs for:
- Releasing active transactions during thread stack unwinding.
- Discarded transaction error codes when a thread exits.
- Undelivered transaction acknowledgments (TRANSACTION_COMPLETE)
  upon thread exit.
- Undelivered process death and freeze notifications when processes
  exit or die.
- Undelivered transactions canceled due to target process death.

Signed-off-by: Jahnavi MN <jahnavimn@google.com>
---
 drivers/android/binder/freeze.rs           |  8 +++++++-
 drivers/android/binder/node.rs             |  8 +++++++-
 drivers/android/binder/rust_binder_main.rs |  9 ++++++++-
 drivers/android/binder/thread.rs           | 18 +++++++++++++++++-
 drivers/android/binder/transaction.rs      |  6 ++++++
 5 files changed, 45 insertions(+), 4 deletions(-)

diff --git a/drivers/android/binder/freeze.rs b/drivers/android/binder/freeze.rs
index d0559ed308ef..b60fbad0f2f3 100644
--- a/drivers/android/binder/freeze.rs
+++ b/drivers/android/binder/freeze.rs
@@ -140,7 +140,13 @@ fn do_work(
         }
     }
 
-    fn cancel(self: DArc<Self>) {}
+    fn cancel(self: DArc<Self>) {
+        binder_debug!(
+            crate::debug::BINDER_DEBUG_DEAD_TRANSACTION,
+            "undelivered freeze notification, {:016x}",
+            self.cookie.0
+        );
+    }
 
     fn should_sync_wakeup(&self) -> bool {
         false
diff --git a/drivers/android/binder/node.rs b/drivers/android/binder/node.rs
index d71f55739772..1d6d623072df 100644
--- a/drivers/android/binder/node.rs
+++ b/drivers/android/binder/node.rs
@@ -1120,7 +1120,13 @@ fn do_work(
         Ok(cmd != BR_DEAD_BINDER)
     }
 
-    fn cancel(self: DArc<Self>) {}
+    fn cancel(self: DArc<Self>) {
+        binder_debug!(
+            crate::debug::BINDER_DEBUG_DEAD_TRANSACTION,
+            "undelivered death notification, {:016x}",
+            self.cookie
+        );
+    }
 
     fn should_sync_wakeup(&self) -> bool {
         false
diff --git a/drivers/android/binder/rust_binder_main.rs b/drivers/android/binder/rust_binder_main.rs
index bf15021524a4..8b8992411cd7 100644
--- a/drivers/android/binder/rust_binder_main.rs
+++ b/drivers/android/binder/rust_binder_main.rs
@@ -262,7 +262,14 @@ fn do_work(
         Ok(true)
     }
 
-    fn cancel(self: DArc<Self>) {}
+    fn cancel(self: DArc<Self>) {
+        if !self.skip.load(Relaxed) {
+            binder_debug!(
+                crate::debug::BINDER_DEBUG_DEAD_TRANSACTION,
+                "undelivered TRANSACTION_COMPLETE"
+            );
+        }
+    }
 
     fn should_sync_wakeup(&self) -> bool {
         false
diff --git a/drivers/android/binder/thread.rs b/drivers/android/binder/thread.rs
index 1656e0c70fef..43bc146505cc 100644
--- a/drivers/android/binder/thread.rs
+++ b/drivers/android/binder/thread.rs
@@ -1150,6 +1150,13 @@ fn unwind_transaction_stack(self: &Arc<Self>) {
             let mut inner = thread.inner.lock();
             inner.pop_transaction_to_reply(thread.as_ref())
         } {
+            binder_debug!(
+                crate::debug::BINDER_DEBUG_DEAD_TRANSACTION,
+                "release process {} transaction {} in, still active",
+                self.process.task.pid(),
+                transaction.debug_id
+            );
+
             let reply = Err(BR_DEAD_REPLY);
             if !transaction.from.deliver_single_reply(reply, &transaction) {
                 break;
@@ -1728,7 +1735,16 @@ fn do_work(
         Ok(true)
     }
 
-    fn cancel(self: DArc<Self>) {}
+    fn cancel(self: DArc<Self>) {
+        let code = self.error_code.load(Relaxed);
+        if code != BR_OK {
+            binder_debug!(
+                crate::debug::BINDER_DEBUG_DEAD_TRANSACTION,
+                "undelivered TRANSACTION_ERROR: {}",
+                code
+            );
+        }
+    }
 
     fn should_sync_wakeup(&self) -> bool {
         false
diff --git a/drivers/android/binder/transaction.rs b/drivers/android/binder/transaction.rs
index f8756c5dfba4..3cb0cb9694de 100644
--- a/drivers/android/binder/transaction.rs
+++ b/drivers/android/binder/transaction.rs
@@ -485,6 +485,12 @@ fn cancel(self: DArc<Self>) {
         if self.target_node.is_some() && self.flags & TF_ONE_WAY == 0 {
             let reply = Err(BR_DEAD_REPLY);
             self.from.deliver_reply(reply, &self);
+        } else {
+            binder_debug!(
+                crate::debug::BINDER_DEBUG_DEAD_TRANSACTION,
+                "undelivered transaction {}, process died",
+                self.debug_id
+            );
         }
 
         self.drop_outstanding_txn();

-- 
2.55.0.rc0.799.gd6f94ed593-goog