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=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,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 1CE96C41604 for ; Sun, 4 Oct 2020 02:41:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E3D2E20679 for ; Sun, 4 Oct 2020 02:41:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726899AbgJDClO (ORCPT ); Sat, 3 Oct 2020 22:41:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48868 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726294AbgJDCjb (ORCPT ); Sat, 3 Oct 2020 22:39:31 -0400 Received: from ZenIV.linux.org.uk (zeniv.linux.org.uk [IPv6:2002:c35c:fd02::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D673CC0613E7; Sat, 3 Oct 2020 19:39:30 -0700 (PDT) Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kOtvt-00BUpS-HI; Sun, 04 Oct 2020 02:39:29 +0000 From: Al Viro To: Linus Torvalds Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Marc Zyngier Subject: [RFC PATCH 02/27] epoll: get rid of epitem->nwait Date: Sun, 4 Oct 2020 03:39:04 +0100 Message-Id: <20201004023929.2740074-2-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 Content-Transfer-Encoding: 8bit Sender: Al Viro Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Al Viro we use it only to indicate allocation failures within queueing callback back to ep_insert(). Might as well use epq.epi for that reporting... Signed-off-by: Al Viro --- fs/eventpoll.c | 46 ++++++++++++++++++++-------------------------- 1 file changed, 20 insertions(+), 26 deletions(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index ae41868d9b35..44aca681d897 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -172,9 +172,6 @@ struct epitem { /* The file descriptor information this item refers to */ struct epoll_filefd ffd; - /* Number of active wait queue attached to poll operations */ - int nwait; - /* List containing poll wait queues */ struct eppoll_entry *pwqlist; @@ -351,12 +348,6 @@ static inline struct epitem *ep_item_from_wait(wait_queue_entry_t *p) return container_of(p, struct eppoll_entry, wait)->base; } -/* Get the "struct epitem" from an epoll queue wrapper */ -static inline struct epitem *ep_item_from_epqueue(poll_table *p) -{ - return container_of(p, struct ep_pqueue, pt)->epi; -} - /* Initialize the poll safe wake up structure */ static void ep_nested_calls_init(struct nested_calls *ncalls) { @@ -1307,24 +1298,28 @@ static int ep_poll_callback(wait_queue_entry_t *wait, unsigned mode, int sync, v static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead, poll_table *pt) { - struct epitem *epi = ep_item_from_epqueue(pt); + struct ep_pqueue *epq = container_of(pt, struct ep_pqueue, pt); + struct epitem *epi = epq->epi; struct eppoll_entry *pwq; - if (epi->nwait >= 0 && (pwq = kmem_cache_alloc(pwq_cache, GFP_KERNEL))) { - init_waitqueue_func_entry(&pwq->wait, ep_poll_callback); - pwq->whead = whead; - pwq->base = epi; - if (epi->event.events & EPOLLEXCLUSIVE) - add_wait_queue_exclusive(whead, &pwq->wait); - else - add_wait_queue(whead, &pwq->wait); - pwq->next = epi->pwqlist; - epi->pwqlist = pwq; - epi->nwait++; - } else { - /* We have to signal that an error occurred */ - epi->nwait = -1; + if (unlikely(!epi)) // an earlier allocation has failed + return; + + pwq = kmem_cache_alloc(pwq_cache, GFP_KERNEL); + if (unlikely(!pwq)) { + epq->epi = NULL; + return; } + + init_waitqueue_func_entry(&pwq->wait, ep_poll_callback); + pwq->whead = whead; + pwq->base = epi; + if (epi->event.events & EPOLLEXCLUSIVE) + add_wait_queue_exclusive(whead, &pwq->wait); + else + add_wait_queue(whead, &pwq->wait); + pwq->next = epi->pwqlist; + epi->pwqlist = pwq; } static void ep_rbtree_insert(struct eventpoll *ep, struct epitem *epi) @@ -1510,7 +1505,6 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, epi->ep = ep; ep_set_ffd(&epi->ffd, tfile, fd); epi->event = *event; - epi->nwait = 0; epi->next = EP_UNACTIVE_PTR; if (epi->event.events & EPOLLWAKEUP) { error = ep_create_wakeup_source(epi); @@ -1555,7 +1549,7 @@ static int ep_insert(struct eventpoll *ep, const struct epoll_event *event, * high memory pressure. */ error = -ENOMEM; - if (epi->nwait < 0) + if (!epq.epi) goto error_unregister; /* We have to drop the new item inside our item list to keep track of it */ -- 2.11.0