From patchwork Tue Jun 11 14:54:53 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Roman Penyaev X-Patchwork-Id: 10987361 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 43D21924 for ; Tue, 11 Jun 2019 14:55:56 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 33202288B5 for ; Tue, 11 Jun 2019 14:55:56 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2785D286EC; Tue, 11 Jun 2019 14:55:56 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B04502843C for ; Tue, 11 Jun 2019 14:55:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404124AbfFKOzV (ORCPT ); Tue, 11 Jun 2019 10:55:21 -0400 Received: from mx2.suse.de ([195.135.220.15]:52618 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2404071AbfFKOzT (ORCPT ); Tue, 11 Jun 2019 10:55:19 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id AF2D9AEF5; Tue, 11 Jun 2019 14:55:18 +0000 (UTC) From: Roman Penyaev Cc: Roman Penyaev , Andrew Morton , Al Viro , Linus Torvalds , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 09/14] epoll: support polling from userspace for ep_remove() Date: Tue, 11 Jun 2019 16:54:53 +0200 Message-Id: <20190611145458.9540-10-rpenyaev@suse.de> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190611145458.9540-1-rpenyaev@suse.de> References: <20190611145458.9540-1-rpenyaev@suse.de> MIME-Version: 1.0 To: unlisted-recipients:; (no To-header on input) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On ep_remove() simply mark a user item with EPOLLREMOVE if the item was ready (i.e. has some bits set). That will prevent further user index entry creation on item ->bit reuse. Signed-off-by: Roman Penyaev Cc: Andrew Morton Cc: Al Viro Cc: Linus Torvalds Cc: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- fs/eventpoll.c | 34 ++++++++++++++++++++++++++++------ 1 file changed, 28 insertions(+), 6 deletions(-) diff --git a/fs/eventpoll.c b/fs/eventpoll.c index 4f541f85c7e5..edf7ba28bce0 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -879,12 +879,30 @@ static __poll_t ep_scan_ready_list(struct eventpoll *ep, return res; } -static void epi_rcu_free(struct rcu_head *head) +static void epi_rcu_free_cb(struct rcu_head *head) { struct epitem *epi = container_of(head, struct epitem, rcu); kmem_cache_free(epi_cache, epi); } +static void uepi_rcu_free_cb(struct rcu_head *head) +{ + struct epitem *epi = container_of(head, struct epitem, rcu); + kmem_cache_free(uepi_cache, uep_item_from_epi(epi)); +} + +static void epi_rcu_free(struct eventpoll *ep, struct epitem *epi) +{ + /* + * Check if `ep` is polled by user here, in this function, not + * in the callback, in order not to control lifetime of the 'ep'. + */ + if (ep_polled_by_user(ep)) + call_rcu(&epi->rcu, uepi_rcu_free_cb); + else + call_rcu(&epi->rcu, epi_rcu_free_cb); +} + static inline int ep_get_bit(struct eventpoll *ep) { bool was_set; @@ -1156,10 +1174,14 @@ static int ep_remove(struct eventpoll *ep, struct epitem *epi) rb_erase_cached(&epi->rbn, &ep->rbr); - write_lock_irq(&ep->lock); - if (ep_is_linked(epi)) - list_del_init(&epi->rdllink); - write_unlock_irq(&ep->lock); + if (ep_polled_by_user(ep)) { + ep_remove_user_item(epi); + } else { + write_lock_irq(&ep->lock); + if (ep_is_linked(epi)) + list_del_init(&epi->rdllink); + write_unlock_irq(&ep->lock); + } wakeup_source_unregister(ep_wakeup_source(epi)); /* @@ -1169,7 +1191,7 @@ static int ep_remove(struct eventpoll *ep, struct epitem *epi) * ep->mtx. The rcu read side, reverse_path_check_proc(), does not make * use of the rbn field. */ - call_rcu(&epi->rcu, epi_rcu_free); + epi_rcu_free(ep, epi); atomic_long_dec(&ep->user->epoll_watches);