From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B7502C4741F for ; Mon, 5 Oct 2020 14:46:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8158B20E65 for ; Mon, 5 Oct 2020 14:46:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601909198; bh=yd0w3Rsk+9IPifIwgAwodb/Vj3PSpZW+XLmovgmCbMw=; h=From:To:Cc:Subject:Date:List-ID:From; b=eRvEJ8rdRmKYf9jcRUBNWW9s0hVDFIjEbf6N1cHzeEAQ0pn5DaHWgKkBQEpSEeY/4 NMnqBwnCcbgNSlKno/HYJ6LHnHWC/k+CV5EVjgMJn+cq6S02n4Su/1+ztryGOr0Ls+ 9s08Lcstc6279nVQl+m1Doy9ZR7Uhaq+myf3loUo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726798AbgJEOqJ (ORCPT ); Mon, 5 Oct 2020 10:46:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:52602 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726648AbgJEOp1 (ORCPT ); Mon, 5 Oct 2020 10:45:27 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8403020B80; Mon, 5 Oct 2020 14:45:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601909119; bh=yd0w3Rsk+9IPifIwgAwodb/Vj3PSpZW+XLmovgmCbMw=; h=From:To:Cc:Subject:Date:From; b=ZIF5NqrGCuMFiDCvDdd3cSsDRCQKrXfOcCzbIlnBWD2V5+rxPxcde6dd1HchEgqiv 0z7JffJrSIdLoGXjWpl72YjZhWGHRpT/9WgUH+xmS8Q/ljInZ56muGrSkgCzZGLi2M ASz2ng6gOGNSrij3EvuxXkVO6jDCKxQv9phtjzTs= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Al Viro , Sasha Levin , linux-fsdevel@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 1/4] epoll: do not insert into poll queues until all sanity checks are done Date: Mon, 5 Oct 2020 10:45:14 -0400 Message-Id: <20201005144517.2527627-1-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Al Viro [ Upstream commit f8d4f44df056c5b504b0d49683fb7279218fd207 ] Signed-off-by: Al Viro Signed-off-by: Sasha Levin --- fs/eventpoll.c | 37 ++++++++++++++++++------------------- 1 file changed, 18 insertions(+), 19 deletions(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index ae1d32344f7ac..f70df53666ed1 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -1527,6 +1527,22 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, RCU_INIT_POINTER(epi->ws, NULL); } + /* Add the current item to the list of active epoll hook for this file */ + spin_lock(&tfile->f_lock); + list_add_tail_rcu(&epi->fllink, &tfile->f_ep_links); + spin_unlock(&tfile->f_lock); + + /* + * Add the current item to the RB tree. All RB tree operations are + * protected by "mtx", and ep_insert() is called with "mtx" held. + */ + ep_rbtree_insert(ep, epi); + + /* now check if we've created too many backpaths */ + error = -EINVAL; + if (full_check && reverse_path_check()) + goto error_remove_epi; + /* Initialize the poll table using the queue callback */ epq.epi = epi; init_poll_funcptr(&epq.pt, ep_ptable_queue_proc); @@ -1549,22 +1565,6 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, if (epi->nwait < 0) goto error_unregister; - /* Add the current item to the list of active epoll hook for this file */ - spin_lock(&tfile->f_lock); - list_add_tail_rcu(&epi->fllink, &tfile->f_ep_links); - spin_unlock(&tfile->f_lock); - - /* - * Add the current item to the RB tree. All RB tree operations are - * protected by "mtx", and ep_insert() is called with "mtx" held. - */ - ep_rbtree_insert(ep, epi); - - /* now check if we've created too many backpaths */ - error = -EINVAL; - if (full_check && reverse_path_check()) - goto error_remove_epi; - /* We have to drop the new item inside our item list to keep track of it */ write_lock_irq(&ep->lock); @@ -1593,6 +1593,8 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, return 0; +error_unregister: + ep_unregister_pollwait(ep, epi); error_remove_epi: spin_lock(&tfile->f_lock); list_del_rcu(&epi->fllink); @@ -1600,9 +1602,6 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, rb_erase_cached(&epi->rbn, &ep->rbr); -error_unregister: - ep_unregister_pollwait(ep, epi); - /* * We need to do this because an event could have been arrived on some * allocated wait queue. Note that we don't care about the ep->ovflist -- 2.25.1