io_uring: don't defer put of cancelled ltimeout

Inline io_link_cancel_timeout() and __io_kill_linked_timeout() into
io_kill_linked_timeout(). That allows to easily move a put of a cancelled
linked timeout out of completion_lock and to not deferring it. It is also
much more readable when not scattered across three different functions.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -1846,57 +1846,39 @@ static void __io_free_req(struct io_kiocb *req)
 	percpu_ref_put(&ctx->refs);
 }
 
-static bool io_link_cancel_timeout(struct io_kiocb *req)
+static void io_kill_linked_timeout(struct io_kiocb *req)
 {
-	struct io_timeout_data *io = req->async_data;
 	struct io_ring_ctx *ctx = req->ctx;
-	int ret;
-
-	ret = hrtimer_try_to_cancel(&io->timer);
-	if (ret != -1) {
-		io_cqring_fill_event(req, -ECANCELED);
-		io_commit_cqring(ctx);
-		io_put_req_deferred(req, 1);
-		return true;
-	}
-
-	return false;
-}
-
-static bool __io_kill_linked_timeout(struct io_kiocb *req)
-{
 	struct io_kiocb *link;
-	bool wake_ev;
-
-	if (list_empty(&req->link_list))
-		return false;
-	link = list_first_entry(&req->link_list, struct io_kiocb, link_list);
+	bool cancelled = false;
+	unsigned long flags;
 
+	spin_lock_irqsave(&ctx->completion_lock, flags);
+	link = list_first_entry_or_null(&req->link_list, struct io_kiocb,
+					link_list);
 	/*
 	 * Can happen if a linked timeout fired and link had been like
 	 * req -> link t-out -> link t-out [-> ...]
 	 */
-	if (!(link->flags & REQ_F_LTIMEOUT_ACTIVE))
-		return false;
-
-	list_del_init(&link->link_list);
-	wake_ev = io_link_cancel_timeout(link);
-	return wake_ev;
-}
-
-static void io_kill_linked_timeout(struct io_kiocb *req)
-{
-	struct io_ring_ctx *ctx = req->ctx;
-	unsigned long flags;
-	bool wake_ev;
+	if (link && (link->flags & REQ_F_LTIMEOUT_ACTIVE)) {
+		struct io_timeout_data *io = link->async_data;
+		int ret;
 
-	spin_lock_irqsave(&ctx->completion_lock, flags);
-	wake_ev = __io_kill_linked_timeout(req);
+		list_del_init(&link->link_list);
+		ret = hrtimer_try_to_cancel(&io->timer);
+		if (ret != -1) {
+			io_cqring_fill_event(link, -ECANCELED);
+			io_commit_cqring(ctx);
+			cancelled = true;
+		}
+	}
 	req->flags &= ~REQ_F_LINK_TIMEOUT;
 	spin_unlock_irqrestore(&ctx->completion_lock, flags);
 
-	if (wake_ev)
+	if (cancelled) {
 		io_cqring_ev_posted(ctx);
+		io_put_req(link);
+	}
 }
 
 static struct io_kiocb *io_req_link_next(struct io_kiocb *req)