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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 A9453C10DCE for ; Wed, 18 Mar 2020 18:05:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 796A720719 for ; Wed, 18 Mar 2020 18:05:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726726AbgCRSF2 (ORCPT ); Wed, 18 Mar 2020 14:05:28 -0400 Received: from Chamillionaire.breakpoint.cc ([193.142.43.52]:60622 "EHLO Chamillionaire.breakpoint.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726506AbgCRSF2 (ORCPT ); Wed, 18 Mar 2020 14:05:28 -0400 Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1jEd4I-0006fk-Fi; Wed, 18 Mar 2020 19:05:26 +0100 Date: Wed, 18 Mar 2020 19:05:26 +0100 From: Florian Westphal To: Eric Dumazet Cc: Florian Westphal , netdev@vger.kernel.org, mptcp@lists.01.org, Eric Dumazet Subject: Re: [RFC mptcp-next] tcp: mptcp: use mptcp receive buffer space to select rcv window Message-ID: <20200318180526.GJ979@breakpoint.cc> References: <20200318141917.2612-1-fw@strlen.de> <48933c49-0889-5dba-29e2-62640e47797a@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <48933c49-0889-5dba-29e2-62640e47797a@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Eric Dumazet wrote: > > @@ -2771,6 +2771,11 @@ u32 __tcp_select_window(struct sock *sk) > > int full_space = min_t(int, tp->window_clamp, allowed_space); > > int window; > > > > + if (sk_is_mptcp(sk)) { > > + mptcp_space(sk, &free_space, &allowed_space); > > + full_space = min_t(int, tp->window_clamp, allowed_space); > > + } > > You could move the full_space = min_t(int, tp->window_clamp, allowed_space); > after this block factorize it. Indeed, will do. > > diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c > > index 40ad7995b13b..aefcbb8bb737 100644 > > --- a/net/mptcp/subflow.c > > +++ b/net/mptcp/subflow.c > > @@ -745,6 +745,23 @@ bool mptcp_subflow_data_available(struct sock *sk) > > return subflow->data_avail; > > } > > > > +/* If ssk has an mptcp parent socket, use the mptcp rcvbuf occupancy, > > + * not the ssk one. > > + * > > + * In mptcp, rwin is about the mptcp-level connection data. > > + * > > + * Data that is still on the ssk rx queue can thus be ignored, > > + * as far as mptcp peer is concerened that data is still inflight. > > + */ > > +void mptcp_space(const struct sock *ssk, int *space, int *full_space) > > +{ > > + const struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(ssk); > > + const struct sock *sk = READ_ONCE(subflow->conn); > > What are the rules protecting subflow->conn lifetime ? > > Why dereferencing sk after this line is safe ? Subflow sockets hold a reference on the master/parent mptcp-socket.