[PATCH v2 4/5] rust_binder: consolidate transaction failure prints

[Alice Ryhl <aliceryhl@google.com>]

When a transaction fails, it currently hits multiple print statements
meaning that a single failure can result in several lines in the kernel
log. This is unnecessary, so consolidate them into one print used for
all transaction failures.

Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
 drivers/android/binder/error.rs       |  4 ---
 drivers/android/binder/thread.rs      | 55 ++++++++++++++---------------------
 drivers/android/binder/transaction.rs | 20 ++-----------
 rust/kernel/error.rs                  |  2 +-
 4 files changed, 26 insertions(+), 55 deletions(-)

diff --git a/drivers/android/binder/error.rs b/drivers/android/binder/error.rs
index 1296072c35d9..aed1c747640b 100644
--- a/drivers/android/binder/error.rs
+++ b/drivers/android/binder/error.rs
@@ -37,10 +37,6 @@ pub(crate) fn new_frozen_oneway() -> Self {
             source: None,
         }
     }
-
-    pub(crate) fn is_dead(&self) -> bool {
-        self.reply == BR_DEAD_REPLY
-    }
 }
 
 /// Convert an errno into a `BinderError` and store the errno used to construct it. The errno
diff --git a/drivers/android/binder/thread.rs b/drivers/android/binder/thread.rs
index a7a190e1b000..bcdf0adfaaff 100644
--- a/drivers/android/binder/thread.rs
+++ b/drivers/android/binder/thread.rs
@@ -26,7 +26,7 @@
 use crate::{
     allocation::{Allocation, AllocationView, BinderObject, BinderObjectRef, NewAllocation},
     defs::*,
-    error::BinderResult,
+    error::{BinderError, BinderResult},
     process::{GetWorkOrRegister, Process},
     ptr_align,
     stats::GLOBAL_STATS,
@@ -1007,17 +1007,7 @@ pub(crate) fn copy_transaction_data(
             size_of::<u64>(),
         );
         let secctx_off = aligned_data_size + offsets_size + buffers_size;
-        let mut alloc = match to_process.buffer_alloc(debug_id, len, info) {
-            Ok(alloc) => alloc,
-            Err(err) => {
-                pr_warn!(
-                    "Failed to allocate buffer. len:{}, is_oneway:{}",
-                    len,
-                    info.is_oneway(),
-                );
-                return Err(err);
-            }
-        };
+        let mut alloc = to_process.buffer_alloc(debug_id, len, info)?;
 
         let mut buffer_reader = UserSlice::new(info.data_ptr, data_size).reader();
         let mut end_of_previous_object = 0;
@@ -1267,6 +1257,9 @@ fn transaction(self: &Arc<Self>, cmd: u32, reader: &mut UserSliceReader) -> Resu
             self.transaction_inner(&mut info)
         };
 
+        // This runs when return work is passed to the caller. This is not
+        // always the same as the transaction failing, as reply errors are
+        // delivered to the remote process.
         if let Err(err) = ret {
             self.push_return_work(err.reply);
             if err.reply != BR_TRANSACTION_COMPLETE {
@@ -1274,13 +1267,21 @@ fn transaction(self: &Arc<Self>, cmd: u32, reader: &mut UserSliceReader) -> Resu
                 if let Some(source) = &err.source {
                     info.errno = source.to_errno();
 
-                    {
-                        let mut inner = self.inner.lock();
-                        inner.extended_error =
-                            ExtendedError::new(info.debug_id as u32, err.reply, source.to_errno());
-                    }
+                    self.inner.lock().extended_error =
+                        ExtendedError::new(info.debug_id as u32, err.reply, source.to_errno());
                 }
+            }
+        }
 
+        if info.oneway_spam_suspect {
+            // If this is both a oneway spam suspect and a failure, we report it twice. This is
+            // useful in case the transaction failed with BR_TRANSACTION_PENDING_FROZEN.
+            info.report_netlink(BR_ONEWAY_SPAM_SUSPECT, &self.process.ctx);
+        }
+        // This runs when the transaction failed.
+        if info.reply != 0 {
+            info.report_netlink(info.reply, &self.process.ctx);
+            if info.errno != 0 {
                 binder_debug!(
                     FailedTransaction,
                     "transaction {} to {}:{} failed {:?}, code {} size {}-{}",
@@ -1293,7 +1294,10 @@ fn transaction(self: &Arc<Self>, cmd: u32, reader: &mut UserSliceReader) -> Resu
                     },
                     info.to_pid,
                     info.to_tid,
-                    err,
+                    BinderError {
+                        reply: info.reply,
+                        source: Error::try_from_errno(info.errno),
+                    },
                     info.code,
                     info.data_size,
                     info.offsets_size
@@ -1301,15 +1305,6 @@ fn transaction(self: &Arc<Self>, cmd: u32, reader: &mut UserSliceReader) -> Resu
             }
         }
 
-        if info.oneway_spam_suspect {
-            // If this is both a oneway spam suspect and a failure, we report it twice. This is
-            // useful in case the transaction failed with BR_TRANSACTION_PENDING_FROZEN.
-            info.report_netlink(BR_ONEWAY_SPAM_SUSPECT, &self.process.ctx);
-        }
-        if info.reply != 0 {
-            info.report_netlink(info.reply, &self.process.ctx);
-        }
-
         Ok(())
     }
 
@@ -1390,12 +1385,6 @@ fn reply_inner(self: &Arc<Self>, info: &mut TransactionInfo) -> BinderResult {
             // At this point we only return `BR_TRANSACTION_COMPLETE` to the caller, and we must let
             // the sender know that the transaction has completed (with an error in this case).
 
-            pr_warn!(
-                "{}:{} reply to {} failed: {err:?}",
-                info.from_pid,
-                info.from_tid,
-                info.to_pid
-            );
             let param = err.source.as_ref().map_or(0, |e| e.to_errno());
             let ee = ExtendedError::new(info.debug_id as u32, err.reply, param);
             orig.from
diff --git a/drivers/android/binder/transaction.rs b/drivers/android/binder/transaction.rs
index 96d45c6816fe..19ad37b0b294 100644
--- a/drivers/android/binder/transaction.rs
+++ b/drivers/android/binder/transaction.rs
@@ -139,21 +139,13 @@ pub(crate) fn new(
         let txn_security_ctx = node_ref.node.flags & FLAT_BINDER_FLAG_TXN_SECURITY_CTX != 0;
         let mut txn_security_ctx_off = if txn_security_ctx { Some(0) } else { None };
         let to = node_ref.node.owner.clone();
-        let mut alloc = match from.copy_transaction_data(
+        let mut alloc = from.copy_transaction_data(
             to.clone(),
             info,
             info.debug_id,
             allow_fds,
             txn_security_ctx_off.as_mut(),
-        ) {
-            Ok(alloc) => alloc,
-            Err(err) => {
-                if !err.is_dead() {
-                    pr_warn!("Failure in copy_transaction_data: {:?}", err);
-                }
-                return Err(err);
-            }
-        };
+        )?;
         if info.is_oneway() {
             if from_parent.is_some() {
                 pr_warn!("Oneway transaction should not be in a transaction stack.");
@@ -194,13 +186,7 @@ pub(crate) fn new_reply(
         allow_fds: bool,
     ) -> BinderResult<DLArc<Self>> {
         let mut alloc =
-            match from.copy_transaction_data(to.clone(), info, info.debug_id, allow_fds, None) {
-                Ok(alloc) => alloc,
-                Err(err) => {
-                    pr_warn!("Failure in copy_transaction_data: {:?}", err);
-                    return Err(err);
-                }
-            };
+            from.copy_transaction_data(to.clone(), info, info.debug_id, allow_fds, None)?;
         if info.flags & TF_CLEAR_BUF != 0 {
             alloc.set_info_clear_on_drop();
         }
diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
index a56ba6309594..380cd3f7276b 100644
--- a/rust/kernel/error.rs
+++ b/rust/kernel/error.rs
@@ -135,7 +135,7 @@ pub fn from_errno(errno: crate::ffi::c_int) -> Error {
     /// Creates an [`Error`] from a kernel error code.
     ///
     /// Returns [`None`] if `errno` is out-of-range.
-    const fn try_from_errno(errno: crate::ffi::c_int) -> Option<Error> {
+    pub const fn try_from_errno(errno: crate::ffi::c_int) -> Option<Error> {
         if errno < -(bindings::MAX_ERRNO as i32) || errno >= 0 {
             return None;
         }

-- 
2.55.0.229.g6434b31f56-goog