From patchwork Sun Oct 4 02:39:25 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Al Viro X-Patchwork-Id: 11815443 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B66E66CA for ; Sun, 4 Oct 2020 02:40:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A0852206B6 for ; Sun, 4 Oct 2020 02:40:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726694AbgJDCkG (ORCPT ); Sat, 3 Oct 2020 22:40:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48886 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726548AbgJDCji (ORCPT ); Sat, 3 Oct 2020 22:39:38 -0400 Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [IPv6:2002:c35c:fd02::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B22B2C0613AE; Sat, 3 Oct 2020 19:39:34 -0700 (PDT) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kOtvx-00BUrr-Dk; Sun, 04 Oct 2020 02:39:33 +0000 From: Al Viro To: Linus Torvalds Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Marc Zyngier Subject: [RFC PATCH 23/27] ep_insert(): move creation of wakeup source past the fl_ep_links insertion Date: Sun, 4 Oct 2020 03:39:25 +0100 Message-Id: <20201004023929.2740074-23-viro@ZenIV.linux.org.uk> X-Mailer: git-send-email 2.25.4 In-Reply-To: <20201004023929.2740074-1-viro@ZenIV.linux.org.uk> References: <20201004023608.GM3421308@ZenIV.linux.org.uk> <20201004023929.2740074-1-viro@ZenIV.linux.org.uk> MIME-Version: 1.0 Sender: Al Viro Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Al Viro That's the beginning of preparations for taking f_ep_links out of struct file. If insertion might fail, we will need a new failure exit. Having wakeup source creation done after that point will simplify life there; ep_remove() can (and commonly does) live with NULL epi->ws, so it can be used for cleanup after ep_create_wakeup_source() failure. It can't be used before the rbtree insertion, though, so if we are to unify all old failure exits, we need to move that thing down. Then we would be free to do simple kmem_cache_free() on the failure to insert into f_ep_links - no wakeup source to leak on that failure exit. Signed-off-by: Al Viro --- fs/eventpoll.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 1efe8a1a022a..66da645d5eb4 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1356,26 +1356,16 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, user_watches = atomic_long_read(&ep->user->epoll_watches); if (unlikely(user_watches >= max_user_watches)) return -ENOSPC; - if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL))) + if (!(epi = kmem_cache_zalloc(epi_cache, GFP_KERNEL))) return -ENOMEM; /* Item initialization follow here ... */ INIT_LIST_HEAD(&epi->rdllink); INIT_LIST_HEAD(&epi->fllink); - epi->pwqlist = NULL; epi->ep = ep; ep_set_ffd(&epi->ffd, tfile, fd); epi->event = *event; epi->next = EP_UNACTIVE_PTR; - if (epi->event.events & EPOLLWAKEUP) { - error = ep_create_wakeup_source(epi); - if (error) { - kmem_cache_free(epi_cache, epi); - return error; - } - } else { - RCU_INIT_POINTER(epi->ws, NULL); - } atomic_long_inc(&ep->user->epoll_watches); @@ -1400,6 +1390,14 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, return -EINVAL; } + if (epi->event.events & EPOLLWAKEUP) { + error = ep_create_wakeup_source(epi); + if (error) { + ep_remove(ep, epi); + return error; + } + } + /* Initialize the poll table using the queue callback */ epq.epi = epi; init_poll_funcptr(&epq.pt, ep_ptable_queue_proc);