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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 8C8D6C433E0 for ; Wed, 10 Feb 2021 09:27:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3EA4364DB1 for ; Wed, 10 Feb 2021 09:27:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230150AbhBJJ1g (ORCPT ); Wed, 10 Feb 2021 04:27:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59926 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230023AbhBJJVS (ORCPT ); Wed, 10 Feb 2021 04:21:18 -0500 Received: from mail-ej1-x62b.google.com (mail-ej1-x62b.google.com [IPv6:2a00:1450:4864:20::62b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7749FC0617AA; Wed, 10 Feb 2021 01:19:27 -0800 (PST) Received: by mail-ej1-x62b.google.com with SMTP id bl23so2828119ejb.5; Wed, 10 Feb 2021 01:19:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=aF26U34aBL8K6bVtwaJCBU2DkCwMTfcd91sYoywprTY=; b=WCKQ+LtKE/UOlQrWFxrHn28+qeGzJlG6joOQzDOEXxMuc52/bvbwwIWCJfpSdEnemZ i9+ZCibdt0/ARIwOmkJfNQQx3wjQfdNwdri68i5YfKJC57taNHzwEPJoLse0GkTvHUBu d3oCV0gH5620B/1/yyQ4yYuEUQNqbhWqbJClWRwEJJRbT06RhSnIMfyV06exk1J9ZNrb Q64okac0fkO1ek5M9R7yG/XL04bchQfjJxOIQzLwwxD3ZPcwLvU0H4pEWMwA6HAWRpT2 yRVark7GGOD3fhXGEPbP7xu6nHE/k6LJijyA0s/cg4QhLuCl+evXa7iYZk4tLFOupnen 81KQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=aF26U34aBL8K6bVtwaJCBU2DkCwMTfcd91sYoywprTY=; b=NuL8WBwMWTr0nZUVmTni0gGobHiChQtd4WZx+/qI3prY1HqfgD2fxfpRzGWXY1t3fy gbAl9uEtCnN8qmBo9gdUtchrSgY7foXnVFLUjK/jH6Zp36hc8cpuE0EnjfPBTj5vDpn+ 7JOGvHPA+Zw8tZxwn1qqklnu7D15yHpGhh2++GsQp1VcVfzcYCbUi5uCHU2FE6mYuvG4 tFbGScLHzSP/rq7sfjdQP8OyTQNyLZgwq202CAau5+LGFNfIq9UyiFHFFkU5qg6ADblf 0v25fmjABWyy0p3TIEqhwrtJBM27fhFlXqVadG+E+N6v/QzlJiu0KchKj75NN73A7Y9n FPTw== X-Gm-Message-State: AOAM532svIlG6suCMdYA+CoNwB+WMl20fYpwU1zSrQPiJijH1fXKKtZA G8XOqEF99xl5kg8BHa14KvZI03MeV0w= X-Google-Smtp-Source: ABdhPJyOFyh2p51yy4aH1LdzJT0MofdRrOkRGV9M/hCkCO5WkB20mLsXy8PAiOIM/CjJqHRPKNce/w== X-Received: by 2002:a17:906:4c85:: with SMTP id q5mr1987915eju.375.1612948766169; Wed, 10 Feb 2021 01:19:26 -0800 (PST) Received: from localhost.localdomain (5-12-227-87.residential.rdsnet.ro. [5.12.227.87]) by smtp.gmail.com with ESMTPSA id u2sm701801ejb.65.2021.02.10.01.19.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Feb 2021 01:19:25 -0800 (PST) From: Vladimir Oltean To: Jakub Kicinski , "David S. Miller" Cc: Andrew Lunn , Vivien Didelot , Florian Fainelli , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bridge@lists.linux-foundation.org, Roopa Prabhu , Nikolay Aleksandrov , Jiri Pirko , Ido Schimmel , Claudiu Manoil , Alexandre Belloni , UNGLinuxDriver@microchip.com, Vadym Kochan , Taras Chornyi , Grygorii Strashko , Ioana Ciornei , Ivan Vecera , linux-omap@vger.kernel.org Subject: [PATCH v3 net-next 08/11] net: bridge: put SWITCHDEV_ATTR_ID_PORT_BRIDGE_FLAGS on the blocking call chain Date: Wed, 10 Feb 2021 11:14:42 +0200 Message-Id: <20210210091445.741269-9-olteanv@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210210091445.741269-1-olteanv@gmail.com> References: <20210210091445.741269-1-olteanv@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Vladimir Oltean Since we would like br_switchdev_set_port_flag to not use an atomic notifier, it should be called from outside spinlock context. We can temporarily drop br->lock, but that creates some concurrency complications (example below is given for sysfs): - There might be an "echo 1 > multicast_flood" simultaneous with an "echo 0 > multicast_flood". The result of this is nondeterministic either way, so I'm not too concerned as long as the result is consistent (no other flags have changed). - There might be an "echo 1 > multicast_flood" simultaneous with an "echo 0 > learning". My expectation is that none of the two writes are "eaten", and the final flags contain BR_MCAST_FLOOD=1 and BR_LEARNING=0 regardless of the order of execution. That is actually possible if, on the commit path, we don't do a trivial "p->flags = flags" which might overwrite bits outside of our mask, but instead we just change the flags corresponding to our mask. Now that br_switchdev_set_port_flag is never called from under br->lock, it runs in sleepable context. All switchdev drivers handle SWITCHDEV_PORT_ATTR_SET as both blocking and atomic, so no changes are needed on that front. Signed-off-by: Vladimir Oltean --- Changes in v3: - Drop the br->lock around br_switchdev_set_port_flag in this patch, for both sysfs and netlink. - Only set/restore the masked bits in p->flags to avoid concurrency issues. Changes in v2: Patch is new. net/bridge/br_netlink.c | 10 +++++++--- net/bridge/br_switchdev.c | 5 ++--- net/bridge/br_sysfs_if.c | 22 ++++++++++++++-------- 3 files changed, 23 insertions(+), 14 deletions(-) diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c index b7731614c036..8f09106966c4 100644 --- a/net/bridge/br_netlink.c +++ b/net/bridge/br_netlink.c @@ -869,7 +869,7 @@ static void br_set_port_flag(struct net_bridge_port *p, struct nlattr *tb[], static int br_setport(struct net_bridge_port *p, struct nlattr *tb[], struct netlink_ext_ack *extack) { - unsigned long old_flags, changed_mask; + unsigned long flags, old_flags, changed_mask; bool br_vlan_tunnel_old; int err; @@ -896,10 +896,14 @@ static int br_setport(struct net_bridge_port *p, struct nlattr *tb[], br_set_port_flag(p, tb, IFLA_BRPORT_ISOLATED, BR_ISOLATED); changed_mask = old_flags ^ p->flags; + flags = p->flags; - err = br_switchdev_set_port_flag(p, p->flags, changed_mask, extack); + spin_unlock_bh(&p->br->lock); + err = br_switchdev_set_port_flag(p, flags, changed_mask, extack); + spin_lock_bh(&p->br->lock); if (err) { - p->flags = old_flags; + p->flags &= ~changed_mask; + p->flags |= (old_flags & changed_mask); goto out; } diff --git a/net/bridge/br_switchdev.c b/net/bridge/br_switchdev.c index dbd94156960f..a79164ee65b9 100644 --- a/net/bridge/br_switchdev.c +++ b/net/bridge/br_switchdev.c @@ -79,9 +79,8 @@ int br_switchdev_set_port_flag(struct net_bridge_port *p, attr.u.brport_flags.val = flags & mask; attr.u.brport_flags.mask = mask; - /* We run from atomic context here */ - err = call_switchdev_notifiers(SWITCHDEV_PORT_ATTR_SET, p->dev, - &info.info, extack); + err = call_switchdev_blocking_notifiers(SWITCHDEV_PORT_ATTR_SET, p->dev, + &info.info, extack); err = notifier_to_errno(err); if (err == -EOPNOTSUPP) return 0; diff --git a/net/bridge/br_sysfs_if.c b/net/bridge/br_sysfs_if.c index 72e92376eef1..3f21fdd1cdaa 100644 --- a/net/bridge/br_sysfs_if.c +++ b/net/bridge/br_sysfs_if.c @@ -68,16 +68,22 @@ static int store_flag(struct net_bridge_port *p, unsigned long v, else flags &= ~mask; - if (flags != p->flags) { - err = br_switchdev_set_port_flag(p, flags, mask, &extack); - if (err) { - netdev_err(p->dev, "%s\n", extack._msg); - return err; - } + if (flags == p->flags) + return 0; - p->flags = flags; - br_port_flags_change(p, mask); + spin_unlock_bh(&p->br->lock); + err = br_switchdev_set_port_flag(p, flags, mask, &extack); + spin_lock_bh(&p->br->lock); + if (err) { + netdev_err(p->dev, "%s\n", extack._msg); + return err; } + + p->flags &= ~mask; + p->flags |= (flags & mask); + + br_port_flags_change(p, mask); + return 0; } -- 2.25.1