From patchwork Thu Oct 21 00:32:12 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Prestwood X-Patchwork-Id: 12573569 X-Patchwork-Delegate: kuba@kernel.org 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2B255C4332F for ; Thu, 21 Oct 2021 00:37:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F1C1660FD8 for ; Thu, 21 Oct 2021 00:37:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231348AbhJUAkD (ORCPT ); Wed, 20 Oct 2021 20:40:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49178 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231200AbhJUAkC (ORCPT ); Wed, 20 Oct 2021 20:40:02 -0400 Received: from mail-pg1-x52c.google.com (mail-pg1-x52c.google.com [IPv6:2607:f8b0:4864:20::52c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5BCCEC061749 for ; Wed, 20 Oct 2021 17:37:47 -0700 (PDT) Received: by mail-pg1-x52c.google.com with SMTP id q187so615732pgq.2 for ; Wed, 20 Oct 2021 17:37:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=CYdH6A8vfhWqL5BtovMJn3N4qQAcZBZVg7EUuFSZS8g=; b=HFBaChGYgH+/L7OCNf/KjxCO9ZLlEU9swZd5wZFXqnYq//+GlXyM0HNwUzK13A2oow hVRc1Gwwayg876CJ0wWOCIMp89KZ2sAZFJC57se8mQn/aCaLASIGOXZAI2MSjUmS9yYO /6C8DRWpcLvojeyzQnBueqIkwDk6+WECA+PD3GBRsyFA2KCPiVE93/d4VjBBO1JU9MrA RIRjLmvBnrW4dEdWQU+7QfrRmWpEJzKmUD3+dB7RajriALtqY9Yz8y8yyGouA6PyDoNe X+Bq+RYkYxfmaSHIuBWuj2STRCdd6ZELJhkI8Famghr5timRILNRz81yflxyLfdTCIYk 1v/Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=CYdH6A8vfhWqL5BtovMJn3N4qQAcZBZVg7EUuFSZS8g=; b=s9K3BKm4VjkEsNV3Vd7FoGA2jmJwElINLnuVnHM4RmsNe7w9BI6ZKc+wJPSrvSL4jr WHT0sJODjKY5188nn+GXz2cGHXhYc7EqgNaMhdKDj7kzePHRkwsSr9ebmHpMa2c6aGlz iuGiYdMZdTXkiQzi/rib6aPSjcJRF9BFSmBK6YnK4Gd32I8LxLBQdvI6ulT27VxH3qD6 89yC8EwErgUKXGSJQjSrNyNaO5CO4i7hZE3Qegz4VADRRL+MErGtmIkKjg+YGPorJZOs kSe+5hV1PLf4vPWxATkrtTSM1q/5qv/CKH76EkDZbXbFrp8wjiZWuCqJeZyC3AhYDw5p OQOQ== X-Gm-Message-State: AOAM531TPgQPP36WrB6NO/P4sKLRpOH/jzAIJ8SivOBkQ5eYkAoWYJq5 Z4L8OV31Q/5ERKsCEJ9n2XvvwSLKbRk= X-Google-Smtp-Source: ABdhPJzEUrmOcpAZ2vD/3zWyusQecOh9U+MqRP0mEQtECZQTmwJH/U//DFxSD2yCTaXQ+aGAS2IfYQ== X-Received: by 2002:a63:7402:: with SMTP id p2mr1921864pgc.472.1634776666655; Wed, 20 Oct 2021 17:37:46 -0700 (PDT) Received: from localhost.localdomain ([50.39.163.188]) by smtp.gmail.com with ESMTPSA id t22sm4164755pfg.148.2021.10.20.17.37.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Oct 2021 17:37:46 -0700 (PDT) From: James Prestwood To: netdev@vger.kernel.org Cc: James Prestwood Subject: [PATCH v5 2/2] net: ndisc: introduce ndisc_evict_nocarrier sysctl parameter Date: Wed, 20 Oct 2021 17:32:12 -0700 Message-Id: <20211021003212.878786-3-prestwoj@gmail.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211021003212.878786-1-prestwoj@gmail.com> References: <20211021003212.878786-1-prestwoj@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org In most situations the neighbor discovery cache should be cleared on a NOCARRIER event which is currently done unconditionally. But for wireless roams the neighbor discovery cache can and should remain intact since the underlying network has not changed. This patch introduces a sysctl option ndisc_evict_nocarrier which can be disabled by a wireless supplicant during a roam. This allows packets to be sent after a roam immediately without having to wait for neighbor discovery. A user reported roughly a 1 second delay after a roam before packets could be sent out (note, on IPv4). This delay was due to the ARP cache being cleared. During testing of this same scenario using IPv6 no delay was noticed, but regardless there is no reason to clear the ndisc cache for wireless roams. Signed-off-by: James Prestwood --- Documentation/networking/ip-sysctl.rst | 9 +++++++++ include/linux/ipv6.h | 1 + include/uapi/linux/ipv6.h | 1 + net/ipv6/addrconf.c | 12 ++++++++++++ net/ipv6/ndisc.c | 9 ++++++++- 5 files changed, 31 insertions(+), 1 deletion(-) diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst index 18fde4ed7a5e..c61cc0219f4c 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -2350,6 +2350,15 @@ ndisc_tclass - INTEGER * 0 - (default) +ndisc_evict_nocarrier - BOOLEAN + Clears the neighbor discovery table on NOCARRIER events. This option is + important for wireless devices where the neighbor discovery cache should + not be cleared when roaming between access points on the same network. + In most cases this should remain as the default (1). + + - 1 - (default): Clear neighbor discover cache on NOCARRIER events. + - 0 - Do not clear neighbor discovery cache on NOCARRIER events. + mldv1_unsolicited_report_interval - INTEGER The interval in milliseconds in which the next unsolicited MLDv1 report retransmit will take place. diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h index ef4a69865737..753e5c0db2a3 100644 --- a/include/linux/ipv6.h +++ b/include/linux/ipv6.h @@ -79,6 +79,7 @@ struct ipv6_devconf { __u32 ioam6_id; __u32 ioam6_id_wide; __u8 ioam6_enabled; + __u8 ndisc_evict_nocarrier; struct ctl_table_header *sysctl_header; }; diff --git a/include/uapi/linux/ipv6.h b/include/uapi/linux/ipv6.h index b243a53fa985..d4178dace0bf 100644 --- a/include/uapi/linux/ipv6.h +++ b/include/uapi/linux/ipv6.h @@ -193,6 +193,7 @@ enum { DEVCONF_IOAM6_ENABLED, DEVCONF_IOAM6_ID, DEVCONF_IOAM6_ID_WIDE, + DEVCONF_NDISC_EVICT_NOCARRIER, DEVCONF_MAX }; diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index d4fae16deec4..398294aa8348 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -241,6 +241,7 @@ static struct ipv6_devconf ipv6_devconf __read_mostly = { .ioam6_enabled = 0, .ioam6_id = IOAM6_DEFAULT_IF_ID, .ioam6_id_wide = IOAM6_DEFAULT_IF_ID_WIDE, + .ndisc_evict_nocarrier = 1, }; static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = { @@ -300,6 +301,7 @@ static struct ipv6_devconf ipv6_devconf_dflt __read_mostly = { .ioam6_enabled = 0, .ioam6_id = IOAM6_DEFAULT_IF_ID, .ioam6_id_wide = IOAM6_DEFAULT_IF_ID_WIDE, + .ndisc_evict_nocarrier = 1, }; /* Check if link is ready: is it up and is a valid qdisc available */ @@ -5542,6 +5544,7 @@ static inline void ipv6_store_devconf(struct ipv6_devconf *cnf, array[DEVCONF_IOAM6_ENABLED] = cnf->ioam6_enabled; array[DEVCONF_IOAM6_ID] = cnf->ioam6_id; array[DEVCONF_IOAM6_ID_WIDE] = cnf->ioam6_id_wide; + array[DEVCONF_NDISC_EVICT_NOCARRIER] = cnf->ndisc_evict_nocarrier; } static inline size_t inet6_ifla6_size(void) @@ -6983,6 +6986,15 @@ static const struct ctl_table addrconf_sysctl[] = { .mode = 0644, .proc_handler = proc_douintvec, }, + { + .procname = "ndisc_evict_nocarrier", + .data = &ipv6_devconf.ndisc_evict_nocarrier, + .maxlen = sizeof(u8), + .mode = 0644, + .proc_handler = proc_dou8vec_minmax, + .extra1 = (void *)SYSCTL_ZERO, + .extra2 = (void *)SYSCTL_ONE, + }, { /* sentinel */ } diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c index 184190b9ea25..4db58c29ab53 100644 --- a/net/ipv6/ndisc.c +++ b/net/ipv6/ndisc.c @@ -1794,6 +1794,7 @@ static int ndisc_netdev_event(struct notifier_block *this, unsigned long event, struct netdev_notifier_change_info *change_info; struct net *net = dev_net(dev); struct inet6_dev *idev; + bool evict_nocarrier; switch (event) { case NETDEV_CHANGEADDR: @@ -1810,10 +1811,16 @@ static int ndisc_netdev_event(struct notifier_block *this, unsigned long event, in6_dev_put(idev); break; case NETDEV_CHANGE: + idev = in6_dev_get(dev); + if (!idev) + evict_nocarrier = true; + else + evict_nocarrier = idev->cnf.ndisc_evict_nocarrier; + change_info = ptr; if (change_info->flags_changed & IFF_NOARP) neigh_changeaddr(&nd_tbl, dev); - if (!netif_carrier_ok(dev)) + if (evict_nocarrier && !netif_carrier_ok(dev)) neigh_carrier_down(&nd_tbl, dev); break; case NETDEV_DOWN: