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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 B0F3FC3A5A8 for ; Wed, 4 Sep 2019 18:23:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8BD3920870 for ; Wed, 4 Sep 2019 18:23:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567621397; bh=H+dch+YFeYG4YZLYOpmbLkkC1J9RsxRQVN+Y3N93/zE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=nr/QaJAEU7v3TvTdv4WnkEOmaE4wjAso7dVIE89sAU44698Na42po7yWmUpuLEjcu 46Pl9wkB4dmOQ7yWwG0m6JvTwZJx2lnyNzZmAQ8PwmX1+vHyxg+90MvIw6U2NiG6+3 VHqx+6PguSCcT1n8wmK8RVSoRFm7UJcdJ/9euqZY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388871AbfIDSDG (ORCPT ); Wed, 4 Sep 2019 14:03:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:43332 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388284AbfIDSDD (ORCPT ); Wed, 4 Sep 2019 14:03:03 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DD26523697; Wed, 4 Sep 2019 18:03:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567620182; bh=H+dch+YFeYG4YZLYOpmbLkkC1J9RsxRQVN+Y3N93/zE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NmSzNQyDtqVGvNqZYW5PBcJAZWI7fp+WFSZ805mhM5R2/X0WJHQbrW/xiMluwgqpm xVKZVygGYATmDHbKCNA55xV+t6aB5hLGeJH7sDhSsGs1wDSa7cla0xcltZ1F4x4coW aB2SDaY4KeHpGxtGRFXt5WncGNvC1GGD3lYETpJw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Jason Baron , Vladimir Rutsky , Soheil Hassas Yeganeh , Neal Cardwell , "David S. Miller" Subject: [PATCH 4.14 20/57] tcp: make sure EPOLLOUT wont be missed Date: Wed, 4 Sep 2019 19:53:48 +0200 Message-Id: <20190904175303.918854334@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20190904175301.777414715@linuxfoundation.org> References: <20190904175301.777414715@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Dumazet [ Upstream commit ef8d8ccdc216f797e66cb4a1372f5c4c285ce1e4 ] As Jason Baron explained in commit 790ba4566c1a ("tcp: set SOCK_NOSPACE under memory pressure"), it is crucial we properly set SOCK_NOSPACE when needed. However, Jason patch had a bug, because the 'nonblocking' status as far as sk_stream_wait_memory() is concerned is governed by MSG_DONTWAIT flag passed at sendmsg() time : long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT); So it is very possible that tcp sendmsg() calls sk_stream_wait_memory(), and that sk_stream_wait_memory() returns -EAGAIN with SOCK_NOSPACE cleared, if sk->sk_sndtimeo has been set to a small (but not zero) value. This patch removes the 'noblock' variable since we must always set SOCK_NOSPACE if -EAGAIN is returned. It also renames the do_nonblock label since we might reach this code path even if we were in blocking mode. Fixes: 790ba4566c1a ("tcp: set SOCK_NOSPACE under memory pressure") Signed-off-by: Eric Dumazet Cc: Jason Baron Reported-by: Vladimir Rutsky Acked-by: Soheil Hassas Yeganeh Acked-by: Neal Cardwell Acked-by: Jason Baron Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/core/stream.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) --- a/net/core/stream.c +++ b/net/core/stream.c @@ -120,7 +120,6 @@ int sk_stream_wait_memory(struct sock *s int err = 0; long vm_wait = 0; long current_timeo = *timeo_p; - bool noblock = (*timeo_p ? false : true); DEFINE_WAIT_FUNC(wait, woken_wake_function); if (sk_stream_memory_free(sk)) @@ -133,11 +132,8 @@ int sk_stream_wait_memory(struct sock *s if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) goto do_error; - if (!*timeo_p) { - if (noblock) - set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); - goto do_nonblock; - } + if (!*timeo_p) + goto do_eagain; if (signal_pending(current)) goto do_interrupted; sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk); @@ -169,7 +165,13 @@ out: do_error: err = -EPIPE; goto out; -do_nonblock: +do_eagain: + /* Make sure that whenever EAGAIN is returned, EPOLLOUT event can + * be generated later. + * When TCP receives ACK packets that make room, tcp_check_space() + * only calls tcp_new_space() if SOCK_NOSPACE is set. + */ + set_bit(SOCK_NOSPACE, &sk->sk_socket->flags); err = -EAGAIN; goto out; do_interrupted: