rust_binder: move (e)poll wait queue to Process

Most processes do not use Rust Binder with epoll, so avoid paying the
synchronize_rcu() cost in drop for those that don't need it. For those
that do, we also manage to replace synchronize_rcu() with kfree_rcu(),
though we introduce an extra allocation.

In case the last ref to an Arc<Thread> is dropped outside of
deferred_release(), this also ensures that synchronize_rcu() is not
called in destructor of Arc<Thread> in other places. Theoretically that
could lead to jank by making other syscalls slow, which would be
problematic.

Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Boqun Feng <boqun@kernel.org>
Link: https://patch.msgid.link/20260707-upgrade-poll-v6-2-4b8fae7bf1d9@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/android/binder/node.rs b/drivers/android/binder/node.rs
index c73cdf82100f..b74ef32b0d94 100644
--- a/drivers/android/binder/node.rs
+++ b/drivers/android/binder/node.rs
@@ -538,7 +538,7 @@ impl Node {
             inner.oneway_todo.push_back(transaction);
         } else {
             inner.has_oneway_transaction = true;
-            guard.push_work(transaction)?;
+            guard.push_work(&self.owner, transaction)?;
         }
         Ok(())
     }
@@ -570,7 +570,7 @@ impl Node {
         let transaction = inner.oneway_todo.pop_front();
         inner.has_oneway_transaction = transaction.is_some();
         if let Some(transaction) = transaction {
-            match guard.push_work(transaction) {
+            match guard.push_work(&self.owner, transaction) {
                 Ok(()) => {}
                 Err((_err, work)) => {
                     // Process is dead.