[PATCH 5/7] rust_binder: Implement the BINDER_DEBUG_FAILED_TRANSACTION logging mask for transaction parsing and routing failures

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

From: Jahnavi MN <jahnavimn@google.com>

This adds dynamic debug logs for:
- Failed replies, target process deaths, and error code deliveries.
- Detailed transaction failure diagnostics (including sender/receiver
  PIDs, TIDs, transaction IDs, buffer sizes, and error codes).
- File descriptor (FD) array validation and translation errors.

Signed-off-by: Jahnavi MN <jahnavimn@google.com>
---
 drivers/android/binder/thread.rs      | 40 +++++++++++++++++++++++++++++++----
 drivers/android/binder/transaction.rs |  5 +++++
 2 files changed, 41 insertions(+), 4 deletions(-)

diff --git a/drivers/android/binder/thread.rs b/drivers/android/binder/thread.rs
index ecf05cebcb3e..1656e0c70fef 100644
--- a/drivers/android/binder/thread.rs
+++ b/drivers/android/binder/thread.rs
@@ -1191,6 +1191,11 @@ fn deliver_single_reply(
             }
 
             if inner.is_dead {
+                binder_debug!(
+                    crate::debug::BINDER_DEBUG_FAILED_TRANSACTION,
+                    "send failed reply for transaction {}, target dead",
+                    transaction.debug_id
+                );
                 return true;
             }
 
@@ -1198,7 +1203,18 @@ fn deliver_single_reply(
                 Ok(work) => {
                     inner.push_work(work);
                 }
-                Err(code) => inner.push_reply_work(code),
+                Err(code) => {
+                    if code == BR_FAILED_REPLY || code == BR_DEAD_REPLY {
+                        binder_debug!(
+                            crate::debug::BINDER_DEBUG_FAILED_TRANSACTION,
+                            "send failed reply for transaction {} to {}:{}",
+                            transaction.debug_id,
+                            self.process.task.pid(),
+                            self.task.pid()
+                        );
+                    }
+                    inner.push_reply_work(code)
+                }
             }
         }
 
@@ -1297,11 +1313,27 @@ fn transaction(self: &Arc<Self>, cmd: u32, reader: &mut UserSliceReader) -> Resu
                     ee.param = source.to_errno();
                 }
 
-                pr_warn!(
-                    "{}:{} transaction to {} failed: {source:?}",
+                binder_debug!(
+                    crate::debug::BINDER_DEBUG_FAILED_TRANSACTION,
+                    "{}:{} transaction {} to {}:{} failed {}/{}/{}, code {} size {}-{} line {}",
                     info.from_pid,
                     info.from_tid,
-                    info.to_pid
+                    if info.is_reply {
+                        "reply"
+                    } else if info.is_oneway() {
+                        "async"
+                    } else {
+                        "call"
+                    },
+                    info.to_pid,
+                    info.to_tid,
+                    info.debug_id,
+                    err.reply,
+                    info.errno,
+                    info.code,
+                    info.data_size,
+                    info.offsets_size,
+                    line!()
                 );
             }
         }
diff --git a/drivers/android/binder/transaction.rs b/drivers/android/binder/transaction.rs
index f9285eb93fc0..f8756c5dfba4 100644
--- a/drivers/android/binder/transaction.rs
+++ b/drivers/android/binder/transaction.rs
@@ -405,6 +405,11 @@ fn do_work(
         } else {
             // On failure to process the list, we send a reply back to the sender and ignore the
             // transaction on the recipient.
+            binder_debug!(
+                crate::debug::BINDER_DEBUG_FAILED_TRANSACTION,
+                "transaction {} fd fixups failed",
+                self.debug_id
+            );
             return Ok(true);
         };
 

-- 
2.55.0.rc0.799.gd6f94ed593-goog