From patchwork Fri Oct 16 10:51:06 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Abeni X-Patchwork-Id: 298891 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=-3.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS autolearn=no 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 20E24C433E7 for ; Fri, 16 Oct 2020 10:51:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 998BD2084C for ; Fri, 16 Oct 2020 10:51:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="MkCL/yHF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2395511AbgJPKve (ORCPT ); Fri, 16 Oct 2020 06:51:34 -0400 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:30499 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2395506AbgJPKve (ORCPT ); Fri, 16 Oct 2020 06:51:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602845492; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=GkfFNwAqoW9BuR2LY2PKLxlnrijd81H/UT1PERKb7QE=; b=MkCL/yHFwOB1XgsNHMUbLBuIuOkCeig/C+fGnB5lvb2ws/H03EebC7D8YsJlESML23Acza ELdAawGL3jTUuVbiK37b+Cy63DiMEMaoTFmG6+XZQBI6pagCuTqQbEaamR/8OxVeytgN0a 6eTO1vynkZwqGkCL7Dtffbjd9aCExcg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-274-mgPwAOS5MUi2z70sNwLCPA-1; Fri, 16 Oct 2020 06:51:30 -0400 X-MC-Unique: mgPwAOS5MUi2z70sNwLCPA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 71BA1102120B; Fri, 16 Oct 2020 10:51:29 +0000 (UTC) Received: from gerbillo.redhat.com (ovpn-112-168.ams2.redhat.com [10.36.112.168]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4B65960E1C; Fri, 16 Oct 2020 10:51:28 +0000 (UTC) From: Paolo Abeni To: netdev@vger.kernel.org Cc: Eric Dumazet , mptcp@lists.01.org Subject: [RFC PATCH 0/2] tcp: factor out a couple of helpers Date: Fri, 16 Oct 2020 12:51:06 +0200 Message-Id: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Upcoming improvement in MPTCP subflows management will require to keep write data enqueued at the MPTCP level. As a side effect, such data could be sent via orphaned TCP subflows after close(). To implement the above MPTCP needs to cope directly with memory allocation failures in do_tcp_sendpages(). The solution proposed in patch 1/2 is to factor-out the relevant slice of do_tcp_sendpages(). Other possible alternatives could be: - duplicating the relevant code inside MPTCP (will require exposing a few additional TCP helpers) or - add an explicit check for orphaned socket in do_tcp_sendpages() Additionally, due to the above, we will need to dispose of already orphaned TCP subflows, avoiding racing with tcp_done(). We need to check the subflow status and destroy it atomically. The solution proposed in patch 2/2 is to factor-out the unlocked body of tcp_close(). These changes are part of a quite larger MPTCP series, with all the other patches touching only MPTCP code. To hopefully simplify the review, such patches are not included here. Please advice if you prefer otherwise - e.g. the whole series as RFC. Paolo Abeni (2): tcp: factor out tcp_build_frag() tcp: factor out __tcp_close() helper include/net/tcp.h | 4 ++ net/ipv4/tcp.c | 128 +++++++++++++++++++++++++++------------------- 2 files changed, 78 insertions(+), 54 deletions(-)