From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: DKIM-Filter: OpenDKIM Filter v2.11.0 smtp1.osuosl.org 9E3BC817A7 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp1.osuosl.org 0C6FD8145C DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=blackwall-org.20210112.gappssmtp.com; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc; bh=8CiaLkECx3krBdKp6oIvGxj9L4zpqrT521rHLsVwe9c=; b=g1jkYz6hbaud7MJPfP0jk8kKHIWsdovgRzcgSUPODZpbjnDzLbWqeUUvMfhcoOvP2o htWSK5oUojOo772tVxb2ovafBDv5nHDssuSAXh0GJ8cr7DNbVH/vcT15T6DsrywtkG5L 9N2MXav1SOO5iaoM2/si+QncOtmAC0ORMqsdfWEui/zHqOVusXm259fNbVucOTCO+opN 5uXJo1y/7kZboMlhv5jq7zi5Bl/1QIwfHlz+GnMU49Cg/+iICR3oJzR79/HXC4KyJO1N JcH24SsTQu4KQUwyRQaXQbX4+AADrP7Ie842gQXGkPCgI4H7n1r5lA5bPBLHy+glgCN6 L/Iw== Message-ID: Date: Sat, 27 Aug 2022 16:54:21 +0300 MIME-Version: 1.0 Content-Language: en-US References: <20220826114538.705433-1-netdev@kapio-technology.com> <20220826114538.705433-2-netdev@kapio-technology.com> From: Nikolay Aleksandrov In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Bridge] [PATCH v5 net-next 1/6] net: bridge: add locked entry fdb flag to extend locked port feature List-Id: Linux Ethernet Bridging List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Ido Schimmel Cc: Andrew Lunn , Alexandre Belloni , Kurt Kanzenbach , Eric Dumazet , linux-kselftest@vger.kernel.org, Hans Schultz , Shuah Khan , Ivan Vecera , Florian Fainelli , Daniel Borkmann , bridge@lists.linux-foundation.org, linux-arm-kernel@lists.infradead.org, Roopa Prabhu , kuba@kernel.org, Paolo Abeni , Vivien Didelot , Woojung Huh , Landen Chao , Jiri Pirko , Christian Marangi , Hauke Mehrtens , Sean Wang , DENG Qingfang , Claudiu Manoil , linux-mediatek@lists.infradead.org, Matthias Brugger , Yuwei Wang , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, UNGLinuxDriver@microchip.com, Vladimir Oltean , davem@davemloft.net On 27/08/2022 16:17, Ido Schimmel wrote: > On Sat, Aug 27, 2022 at 02:30:25PM +0300, Nikolay Aleksandrov wrote: >> On 26/08/2022 14:45, Hans Schultz wrote: >> Please add the blackhole flag in a separate patch. > > +1 > > [...] > >>> @@ -185,6 +196,9 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb >>> if (test_bit(BR_FDB_LOCAL, &dst->flags)) >>> return br_pass_frame_up(skb); >>> >>> + if (test_bit(BR_FDB_BLACKHOLE, &dst->flags)) >>> + goto drop; >>> + >> Not happy about adding a new test in arguably the most used fast-path, but I don't see >> a better way to do blackhole right now. Could you please make it an unlikely() ? >> >> I guess the blackhole flag will be allowed for user-space to set at some point, why >> not do it from the start? >> >> Actually adding a BR_FDB_LOCAL and BR_FDB_BLACKHOLE would be a conflict above - >> the packet will be received. So you should move the blackhole check above the >> BR_FDB_LOCAL one if user-space is allowed to set it to any entry. > > Agree about unlikely() and making it writeable from user space from the > start. This flag is different from the "locked" flag that should only be > ever set by the kernel. > > Regarding BR_FDB_LOCAL, I think BR_FDB_BLACKHOLE should only be allowed > with BR_FDB_LOCAL as these entries are similar in the following ways: > > 1. It doesn't make sense to associate a blackhole entry with a specific > port. The packet will never be forwarded to this port, but dropped by > the bridge. This means user space will add them on the bridge itself: > Right, good point. > # bridge fdb add 00:11:22:33:44:55 dev br0 self local blackhole > > 2. If you agree that these entries should not be associated with a > specific port, then it also does not make sense to subject them to > ageing and roaming, just like existing local/permanent entries. > > The above allows us to push the new check under the BR_FDB_LOCAL check: > hmm.. so only the driver will be allowed to add non-BR_FDB_LOCAL blackhole entries with locked flag set as well, that sounds ok as they will be extern_learn and enforced by it. It is a little discrepancy as we cannot add similar entries in SW but it really doesn't make any sense to have blackhole fdbs pointing to a port. SW won't be able to have a locked entry w/ blackhole set, but I like that it is hidden in the fdb local case when fwding and that's good enough for me. > diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c > index 68b3e850bcb9..4357445529a5 100644 > --- a/net/bridge/br_input.c > +++ b/net/bridge/br_input.c > @@ -182,8 +182,11 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb > if (dst) { > unsigned long now = jiffies; > > - if (test_bit(BR_FDB_LOCAL, &dst->flags)) > + if (test_bit(BR_FDB_LOCAL, &dst->flags)) { > + if (unlikely(test_bit(BR_FDB_BLACKHOLE, &dst->flags))) > + goto drop; > return br_pass_frame_up(skb); > + } > > if (now != dst->used) > dst->used = now;