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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 77951C7EE20 for ; Tue, 18 Apr 2023 12:33:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231689AbjDRMdy (ORCPT ); Tue, 18 Apr 2023 08:33:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47626 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231693AbjDRMds (ORCPT ); Tue, 18 Apr 2023 08:33:48 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 201AACC1F for ; Tue, 18 Apr 2023 05:33:32 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6F3BC63215 for ; Tue, 18 Apr 2023 12:33:32 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 83393C433EF; Tue, 18 Apr 2023 12:33:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1681821211; bh=il9EZBMpSktWRx/YbZv5P14enCH5plIWGFDp/lepElk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XVGRe+hv+C3nEanL2o+86O1i9vV5i5xeqtgASX5SQTcmdMN+Fpt9IGeXiRtZAB5LT bpAs0fRZwUqqAaon0Jc5qYmk1QuHKPAs3+DodgQkncGah2kgYgfmwUVbNid3rosXlY 8Xx7A87AxF3kkKOrGh3A3ZeSIapl0e7lceJs+Hy0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Michal Sojka , Jakub Jira , Oliver Hartkopp , Marc Kleine-Budde Subject: [PATCH 5.10 041/124] can: isotp: isotp_ops: fix poll() to not report false EPOLLOUT events Date: Tue, 18 Apr 2023 14:21:00 +0200 Message-Id: <20230418120311.321342969@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230418120309.539243408@linuxfoundation.org> References: <20230418120309.539243408@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Michal Sojka commit 79e19fa79cb5d5f1b3bf3e3ae24989ccb93c7b7b upstream. When using select()/poll()/epoll() with a non-blocking ISOTP socket to wait for when non-blocking write is possible, a false EPOLLOUT event is sometimes returned. This can happen at least after sending a message which must be split to multiple CAN frames. The reason is that isotp_sendmsg() returns -EAGAIN when tx.state is not equal to ISOTP_IDLE and this behavior is not reflected in datagram_poll(), which is used in isotp_ops. This is fixed by introducing ISOTP-specific poll function, which suppresses the EPOLLOUT events in that case. v2: https://lore.kernel.org/all/20230302092812.320643-1-michal.sojka@cvut.cz v1: https://lore.kernel.org/all/20230224010659.48420-1-michal.sojka@cvut.cz https://lore.kernel.org/all/b53a04a2-ba1f-3858-84c1-d3eb3301ae15@hartkopp.net Signed-off-by: Michal Sojka Reported-by: Jakub Jira Tested-by: Oliver Hartkopp Acked-by: Oliver Hartkopp Fixes: e057dd3fc20f ("can: add ISO 15765-2:2016 transport protocol") Link: https://lore.kernel.org/all/20230331125511.372783-1-michal.sojka@cvut.cz Cc: stable@vger.kernel.org Signed-off-by: Marc Kleine-Budde Signed-off-by: Greg Kroah-Hartman --- net/can/isotp.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) --- a/net/can/isotp.c +++ b/net/can/isotp.c @@ -1480,6 +1480,21 @@ static int isotp_init(struct sock *sk) return 0; } +static __poll_t isotp_poll(struct file *file, struct socket *sock, poll_table *wait) +{ + struct sock *sk = sock->sk; + struct isotp_sock *so = isotp_sk(sk); + + __poll_t mask = datagram_poll(file, sock, wait); + poll_wait(file, &so->wait, wait); + + /* Check for false positives due to TX state */ + if ((mask & EPOLLWRNORM) && (so->tx.state != ISOTP_IDLE)) + mask &= ~(EPOLLOUT | EPOLLWRNORM); + + return mask; +} + static int isotp_sock_no_ioctlcmd(struct socket *sock, unsigned int cmd, unsigned long arg) { @@ -1495,7 +1510,7 @@ static const struct proto_ops isotp_ops .socketpair = sock_no_socketpair, .accept = sock_no_accept, .getname = isotp_getname, - .poll = datagram_poll, + .poll = isotp_poll, .ioctl = isotp_sock_no_ioctlcmd, .gettstamp = sock_gettstamp, .listen = sock_no_listen,