binder: pre-allocate binder_transaction

Move the allocation of 'struct binder_transaction' to the beginning of
the binder_transaction() function, along with the initialization of all
the members that are known at that time. This minor refactoring helps to
consolidate the usage of transaction information at later points.

This patch is in preparation for binder's generic netlink implementation
and no functional changes are intended.

Signed-off-by: Carlos Llamas <cmllamas@google.com>
Link: https://lore.kernel.org/r/20250727182932.2499194-2-cmllamas@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 30 insertions, 34 deletions

diff --git a/drivers/android/binder.c b/drivers/android/binder.c
index 28634f786e70..d1d1051cdedb 100644
--- a/drivers/android/binder.c
+++ b/drivers/android/binder.c
@@ -3042,6 +3042,30 @@ static void binder_transaction(struct binder_proc *proc,
 	binder_set_extended_error(&thread->ee, t_debug_id, BR_OK, 0);
 	binder_inner_proc_unlock(proc);
 
+	t = kzalloc(sizeof(*t), GFP_KERNEL);
+	if (!t) {
+		binder_txn_error("%d:%d cannot allocate transaction\n",
+				 thread->pid, proc->pid);
+		return_error = BR_FAILED_REPLY;
+		return_error_param = -ENOMEM;
+		return_error_line = __LINE__;
+		goto err_alloc_t_failed;
+	}
+	INIT_LIST_HEAD(&t->fd_fixups);
+	binder_stats_created(BINDER_STAT_TRANSACTION);
+	spin_lock_init(&t->lock);
+	t->debug_id = t_debug_id;
+	t->start_time = t_start_time;
+	t->from_pid = proc->pid;
+	t->from_tid = thread->pid;
+	t->sender_euid = task_euid(proc->tsk);
+	t->code = tr->code;
+	t->flags = tr->flags;
+	t->priority = task_nice(current);
+	t->work.type = BINDER_WORK_TRANSACTION;
+	if (!reply && !(tr->flags & TF_ONE_WAY))
+		t->from = thread;
+
 	if (reply) {
 		binder_inner_proc_lock(proc);
 		in_reply_to = thread->transaction_stack;
@@ -3228,24 +3252,13 @@ static void binder_transaction(struct binder_proc *proc,
 		}
 		binder_inner_proc_unlock(proc);
 	}
+
+	t->to_proc = target_proc;
+	t->to_thread = target_thread;
 	if (target_thread)
 		e->to_thread = target_thread->pid;
 	e->to_proc = target_proc->pid;
 
-	/* TODO: reuse incoming transaction for reply */
-	t = kzalloc(sizeof(*t), GFP_KERNEL);
-	if (t == NULL) {
-		binder_txn_error("%d:%d cannot allocate transaction\n",
-			thread->pid, proc->pid);
-		return_error = BR_FAILED_REPLY;
-		return_error_param = -ENOMEM;
-		return_error_line = __LINE__;
-		goto err_alloc_t_failed;
-	}
-	INIT_LIST_HEAD(&t->fd_fixups);
-	binder_stats_created(BINDER_STAT_TRANSACTION);
-	spin_lock_init(&t->lock);
-
 	tcomplete = kzalloc(sizeof(*tcomplete), GFP_KERNEL);
 	if (tcomplete == NULL) {
 		binder_txn_error("%d:%d cannot allocate work for transaction\n",
@@ -3257,9 +3270,6 @@ static void binder_transaction(struct binder_proc *proc,
 	}
 	binder_stats_created(BINDER_STAT_TRANSACTION_COMPLETE);
 
-	t->debug_id = t_debug_id;
-	t->start_time = t_start_time;
-
 	if (reply)
 		binder_debug(BINDER_DEBUG_TRANSACTION,
 			     "%d:%d BC_REPLY %d -> %d:%d, data size %lld-%lld-%lld\n",
@@ -3275,19 +3285,6 @@ static void binder_transaction(struct binder_proc *proc,
 			     (u64)tr->data_size, (u64)tr->offsets_size,
 			     (u64)extra_buffers_size);
 
-	if (!reply && !(tr->flags & TF_ONE_WAY))
-		t->from = thread;
-	else
-		t->from = NULL;
-	t->from_pid = proc->pid;
-	t->from_tid = thread->pid;
-	t->sender_euid = task_euid(proc->tsk);
-	t->to_proc = target_proc;
-	t->to_thread = target_thread;
-	t->code = tr->code;
-	t->flags = tr->flags;
-	t->priority = task_nice(current);
-
 	if (target_node && target_node->txn_security_ctx) {
 		u32 secid;
 		size_t added_size;
@@ -3684,7 +3681,6 @@ static void binder_transaction(struct binder_proc *proc,
 		tcomplete->type = BINDER_WORK_TRANSACTION_ONEWAY_SPAM_SUSPECT;
 	else
 		tcomplete->type = BINDER_WORK_TRANSACTION_COMPLETE;
-	t->work.type = BINDER_WORK_TRANSACTION;
 
 	if (reply) {
 		binder_enqueue_thread_work(thread, tcomplete);
@@ -3783,9 +3779,6 @@ err_get_secctx_failed:
 err_alloc_tcomplete_failed:
 	if (trace_binder_txn_latency_free_enabled())
 		binder_txn_latency_free(t);
-	kfree(t);
-	binder_stats_deleted(BINDER_STAT_TRANSACTION);
-err_alloc_t_failed:
 err_bad_todo_list:
 err_bad_call_stack:
 err_empty_call_stack:
@@ -3795,6 +3788,9 @@ err_invalid_target_handle:
 		binder_dec_node(target_node, 1, 0);
 		binder_dec_node_tmpref(target_node);
 	}
+	kfree(t);
+	binder_stats_deleted(BINDER_STAT_TRANSACTION);
+err_alloc_t_failed:
 
 	binder_debug(BINDER_DEBUG_FAILED_TRANSACTION,
 		     "%d:%d transaction %s to %d:%d failed %d/%d/%d, code %u size %lld-%lld line %d\n",