[PATCH v4 4/6] rust_binder: keep NodeDeath in NodeRefInfo during process cleanup

[Alice Ryhl]

By keeping the NodeDeath inside the NodeRefInfo structure during process
cleanup, we avoid running its destructor under the node_refs lock. It is
still dropped shortly thereafter when the entire rbtree holding the
NodeRefInfo objects is dropped, but that occurs outside of the lock.

Reviewed-by: Matthew Maurer <mmaurer@xxxxxxxxxx>
Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
---
 drivers/android/binder/process.rs | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/android/binder/process.rs b/drivers/android/binder/process.rs
index 505e0bc52748..410218505417 100644
--- a/drivers/android/binder/process.rs
+++ b/drivers/android/binder/process.rs
@@ -1389,13 +1389,11 @@ fn deferred_release(self: Arc<Self>) {
             // SAFETY: We are removing the `NodeRefInfo` from the right node.
             unsafe { info.node_ref2().node.remove_node_info(info) };
 
-            // Remove all death notifications from the nodes (that belong to a different process).
-            let death = if let Some(existing) = info.death().take() {
-                existing
-            } else {
-                continue;
-            };
-            death.set_cleared(false);
+            // Clear death notifications from the nodes (that belong to a different process).
+            // No need to remove them from `info` as we clear info below.
+            if let Some(death) = info.death().as_ref() {
+                death.set_cleared(false);
+            }
         }
 
         // Clean up freeze listeners.

-- 
2.55.0.rc2.803.g1fd1e6609c-goog