linux-kernel - Re: [PATCH net v2] selftests: forwarding: Avoid false MDB delete/flush failures

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Message-ID: <CAAvyFNiAXb7wuDMi6tRVuzHUwkSwtCtJOzM7LGxk5nDEtaqgyQ@mail.gmail.com>
Date: Fri, 20 Sep 2024 22:54:29 +1000
From: Jamie Bainbridge <jamie.bainbridge@...il.com>
To: Ido Schimmel <idosch@...dia.com>
Cc: "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Shuah Khan <shuah@...nel.org>, 
	Nikolay Aleksandrov <razor@...ckwall.org>, netdev@...r.kernel.org, 
	linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net v2] selftests: forwarding: Avoid false MDB
 delete/flush failures

On Fri, 20 Sept 2024 at 00:56, Ido Schimmel <idosch@...dia.com> wrote:
>
> Hi,
>
> Thanks for the patch and sorry for the late reply (was OOO).
>
> On Mon, Sep 16, 2024 at 07:49:05PM +1000, Jamie Bainbridge wrote:
> > Running this test on a small system produces different failures every
> > test checking deletions, and some flushes. From different test runs:
> >
> > TEST: Common host entries configuration tests (L2)                [FAIL]
> >   Failed to delete L2 host entry
> >
> > TEST: Common port group entries configuration tests (IPv4 (S, G)) [FAIL]
> >   IPv4 (S, G) entry with VLAN 10 not deleted when VLAN was not specified
> >
> > TEST: Common port group entries configuration tests (IPv6 (*, G)) [FAIL]
> >   IPv6 (*, G) entry with VLAN 10 not deleted when VLAN was not specified
> >
> > TEST: Flush tests                                                 [FAIL]
> >   Entry not flushed by specified VLAN ID
> >
> > TEST: Flush tests                                                 [FAIL]
> >   IPv6 host entry not flushed by "nopermanent" state
> >
> > Add a short sleep after deletion and flush to resolve this.
>
> The port group entry is removed from MDB entry's list synchronously, but
> the MDB entry itself is removed from the hash table asynchronously and
> the MDB get query will only return an error if an entry was not found
> there.
>
> IOW, I think that when you do get a response after deletion, the entry
> you get is empty.
>
> Can you please test the following patch [1] (w/o yours, obviously)?
>
> [1]
> diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
> index bc37e47ad829..1a52a0bca086 100644
> --- a/net/bridge/br_mdb.c
> +++ b/net/bridge/br_mdb.c
> @@ -1674,7 +1674,7 @@ int br_mdb_get(struct net_device *dev, struct nlattr *tb[], u32 portid, u32 seq,
>         spin_lock_bh(&br->multicast_lock);
>
>         mp = br_mdb_ip_get(br, &group);
> -       if (!mp) {
> +       if (!mp || (!mp->ports && !mp->host_joined)) {
>                 NL_SET_ERR_MSG_MOD(extack, "MDB entry not found");
>                 err = -ENOENT;
>                 goto unlock;

This works perfectly for me. Previously I would get at least 2
failures in 10. Without my patch and with the above patch, 100 tests
pass without any failure.

Many thanks for looking at this!

Jamie