static int binder_thread_release()

in binder.c [4681:4769]

• 60 lines of code
• 12 McCabe index (conditional complexity)

static int binder_thread_release(struct binder_proc *proc,
				 struct binder_thread *thread)
{
	struct binder_transaction *t;
	struct binder_transaction *send_reply = NULL;
	int active_transactions = 0;
	struct binder_transaction *last_t = NULL;

	binder_inner_proc_lock(thread->proc);
	/*
	 * take a ref on the proc so it survives
	 * after we remove this thread from proc->threads.
	 * The corresponding dec is when we actually
	 * free the thread in binder_free_thread()
	 */
	proc->tmp_ref++;
	/*
	 * take a ref on this thread to ensure it
	 * survives while we are releasing it
	 */
	atomic_inc(&thread->tmp_ref);
	rb_erase(&thread->rb_node, &proc->threads);
	t = thread->transaction_stack;
	if (t) {
		spin_lock(&t->lock);
		if (t->to_thread == thread)
			send_reply = t;
	} else {
		__acquire(&t->lock);
	}
	thread->is_dead = true;

	while (t) {
		last_t = t;
		active_transactions++;
		binder_debug(BINDER_DEBUG_DEAD_TRANSACTION,
			     "release %d:%d transaction %d %s, still active\n",
			      proc->pid, thread->pid,
			     t->debug_id,
			     (t->to_thread == thread) ? "in" : "out");

		if (t->to_thread == thread) {
			thread->proc->outstanding_txns--;
			t->to_proc = NULL;
			t->to_thread = NULL;
			if (t->buffer) {
				t->buffer->transaction = NULL;
				t->buffer = NULL;
			}
			t = t->to_parent;
		} else if (t->from == thread) {
			t->from = NULL;
			t = t->from_parent;
		} else
			BUG();
		spin_unlock(&last_t->lock);
		if (t)
			spin_lock(&t->lock);
		else
			__acquire(&t->lock);
	}
	/* annotation for sparse, lock not acquired in last iteration above */
	__release(&t->lock);

	/*
	 * If this thread used poll, make sure we remove the waitqueue from any
	 * poll data structures holding it.
	 */
	if (thread->looper & BINDER_LOOPER_STATE_POLL)
		wake_up_pollfree(&thread->wait);

	binder_inner_proc_unlock(thread->proc);

	/*
	 * This is needed to avoid races between wake_up_pollfree() above and
	 * someone else removing the last entry from the queue for other reasons
	 * (e.g. ep_remove_wait_queue() being called due to an epoll file
	 * descriptor being closed).  Such other users hold an RCU read lock, so
	 * we can be sure they're done after we call synchronize_rcu().
	 */
	if (thread->looper & BINDER_LOOPER_STATE_POLL)
		synchronize_rcu();

	if (send_reply)
		binder_send_failed_reply(send_reply, BR_DEAD_REPLY);
	binder_release_work(proc, &thread->todo);
	binder_thread_dec_tmpref(thread);
	return active_transactions;
}