netdev - Re: [RFC PATCH v3 nf-next] selftests: netfilter: Add bridge

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Message-ID: <be179c64-8c14-4f38-bab2-4597afc63341@gmail.com>
Date: Sat, 4 Oct 2025 13:01:56 +0200
From: Eric Woudstra <ericwouds@...il.com>
To: Florian Westphal <fw@...len.de>
Cc: Pablo Neira Ayuso <pablo@...filter.org>,
 Jozsef Kadlecsik <kadlec@...filter.org>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Simon Horman <horms@...nel.org>, Shuah Khan <shuah@...nel.org>,
 Nikolay Aleksandrov <razor@...ckwall.org>,
 Vladimir Oltean <olteanv@...il.com>, netfilter-devel@...r.kernel.org,
 netdev@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [RFC PATCH v3 nf-next] selftests: netfilter: Add
 bridge_fastpath.sh



On 9/30/25 9:19 PM, Florian Westphal wrote:
> Eric Woudstra <ericwouds@...il.com> wrote:
>> Add a script to test various scenarios where a bridge is involved
>> in the fastpath. It runs tests in the forward path, and also in
>> a bridged path.
> 
> Why is this still an RFC, what is missing to appy this?

Changes in the patchset "conntrack: bridge: add double vlan, pppoe and
pppoe-in-q" has lead to changes in this script. I'm waiting for that
patch-set is to be accepted. Then I will send this script without the
rfc tag.
> Also:
> 
> PASS:  forward,        without vlan-device, without vlan encap, client1, without fastpath
> 
> net/bridge/br_private.h:1627 suspicious rcu_dereference_protected() usage!
> 
> other info that might help us debug this:
> 
> rcu_scheduler_active = 2, debug_locks = 1
> 7 locks held by socat/410:
>  #0: ffff88800d7a9c90 (sk_lock-AF_INET){+.+.}-{0:0}, at: inet_stream_connect+0x43/0xa0
>  #1: ffffffff9a779900 (rcu_read_lock){....}-{1:3}, at: __ip_queue_xmit+0x62/0x1830
>  #2: ffffffff9a779900 (rcu_read_lock){....}-{1:3}, at: ip_output+0x57/0x3c0
>  #3: ffffffff9a779900 (rcu_read_lock){....}-{1:3}, at: ip_finish_output2+0x263/0x17d0
>  #4: ffffffff9a779900 (rcu_read_lock){....}-{1:3}, at: process_backlog+0x38a/0x14b0
>  #5: ffffffff9a779900 (rcu_read_lock){....}-{1:3}, at: netif_receive_skb_internal+0x83/0x330
>  #6: ffffffff9a779900 (rcu_read_lock){....}-{1:3}, at: nf_hook.constprop.0+0x8a/0x440
> 
> stack backtrace:
> CPU: 0 UID: 0 PID: 410 Comm: socat Not tainted 6.17.0-rc7-virtme #1 PREEMPT(full)
> Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> Call Trace:
>  <IRQ>
>  dump_stack_lvl+0x6f/0xb0
>  lockdep_rcu_suspicious.cold+0x4f/0xb1
>  br_vlan_fill_forward_path_pvid+0x32c/0x410 [bridge]
>  br_fill_forward_path+0x7a/0x4d0 [bridge]
>  ...
> 
> I did not see a mention of this, nor a bug fix.
> 
> Its a pre-existing bug, br_vlan_fill_forward_path_pvid uses
> br_vlan_group() instead of _rcu version.
> 
> Will you send a patch for this?
I had this as part of an upcoming patch-set, but I will remove it from
there and send it as a separate patch. I assume this can go to nf
instead of nf-next, as it is a bugfix?