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Date:   Sat, 7 Jan 2023 02:17:07 +0100
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Subject: Re: BUG: tools/testing/selftests/net/l2_tos_ttl_inherit.sh hangs when
 selftest restarted
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To:     Guillaume Nault <gnault@redhat.com>
Cc:     linux-kselftest@vger.kernel.org,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>, Shuah Khan <shuah@kernel.org>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
References: <924f1062-ab59-9b88-3b43-c44e73a30387@alu.unizg.hr>
 <Y7i5cT1AlyC53hzN@debian>
From:   Mirsad Goran Todorovac <mirsad.todorovac@alu.unizg.hr>
In-Reply-To: <Y7i5cT1AlyC53hzN@debian>
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On 07. 01. 2023. 01:14, Guillaume Nault wrote:
> On Fri, Jan 06, 2023 at 02:44:11AM +0100, Mirsad Goran Todorovac wrote:
>> [root@pc-mtodorov linux_torvalds]# tools/testing/selftests/net/l2_tos_ttl_inherit.sh
>> ┌────────┬───────┬───────┬──────────────┬──────────────┬───────┬────────┐
>> ├────────┼───────┼───────┼──────────────┼──────────────┼───────┼────────┤
>> │  Type  │ outer | inner │     tos      │      ttl     │  vlan │ result │
>> ├────────┼───────┼───────┼──────────────┼──────────────┼───────┼────────┤
>> │    gre │     4 │     4 │ inherit 0xc4 │  inherit 116 │ false │Cannot create namespace file "/var/run/netns/testing": File exists
>> RTNETLINK answers: File exists
>> RTNETLINK answers: File exists
>> RTNETLINK answers: File exists
> 
> You probably have leftovers from a previous test case. In particular
> the "testing" network name space already exists, which prevents the
> script from creating it. You can delete it manually with
> "ip netns del testing". If this netns is there because of a previous
> incomplete run of l2_tos_ttl_inherit.sh, then you'll likely need to
> also remove the tunnel interface it created in your current netns
> ("ip link del tep0").

Thanks, it worked :)

> Ideally this script wouldn't touch the current netns and would clean up
> its environment in all cases upon exit. I have a patch almost ready
> that does just that.

As these interfaces were not cleared by "make kselftest-clean",
this patch with a cleanup trap would be most welcome.

However, after the cleanup above, the ./l2_tos_ttl_inherit.sh
script hangs at the spot where it did in the first place (but
only on Lenovo desktop 10TX000VCR with BIOS M22KT49A from
11/10/2022, AlmaLinux 8.7, and kernel 6.2-rc2; not on Lenovo
Ideapad3 with Ubuntu 22.10, where it worked like a charm with
the same kernel RC).

The point of hang is this:

[root@pc-mtodorov net]# ./l2_tos_ttl_inherit.sh
┌────────┬───────┬───────┬──────────────┬──────────────┬───────┬────────┐
├────────┼───────┼───────┼──────────────┼──────────────┼───────┼────────┤
│  Type  │ outer | inner │     tos      │      ttl     │  vlan │ result │
├────────┼───────┼───────┼──────────────┼──────────────┼───────┼────────┤
│    gre │     4 │     4 │ inherit 0xb8 │  inherit 102 │ false │     OK │
│    gre │     4 │     4 │ inherit 0x10 │   inherit 53 │  true │     OK │
│    gre │     4 │     4 │   fixed 0xa8 │    fixed 230 │ false │     OK │
│    gre │     4 │     4 │   fixed 0x0c │     fixed 96 │  true │     OK │
├────────┼───────┼───────┼──────────────┼──────────────┼───────┼────────┤
│    gre │     4 │     6 │ inherit 0xbc │  inherit 159 │ false │     OK │
│    gre │     4 │     6 │ inherit 0x5c │  inherit 242 │  true │     OK │
│    gre │     4 │     6 │   fixed 0x38 │    fixed 113 │ false │     OK │
│    gre │     4 │     6 │   fixed 0x78 │     fixed 34 │  true │     OK │
├────────┼───────┼───────┼──────────────┼──────────────┼───────┼────────┤
│    gre │     4 │ other │ inherit 0xec │   inherit 69 │ false │     OK │
│    gre │     4 │ other │ inherit 0xf0 │  inherit 201 │  true │     OK │
│    gre │     4 │ other │   fixed 0xec │     fixed 14 │ false │     OK │
│    gre │     4 │ other │   fixed 0xe4 │     fixed 15 │  true │     OK │
├────────┼───────┼───────┼──────────────┼──────────────┼───────┼────────┤
│  Type  │ outer | inner │     tos      │      ttl     │  vlan │ result │
├────────┼───────┼───────┼──────────────┼──────────────┼───────┼────────┤
│    gre │     6 │     4 │ inherit 0xc4 │   inherit 21 │ false │     OK │
│    gre │     6 │     4 │ inherit 0xc8 │  inherit 230 │  true │     OK │
│    gre │     6 │     4 │   fixed 0x24 │    fixed 193 │ false │     OK │
│    gre │     6 │     4 │   fixed 0x1c │    fixed 200 │  true │     OK │
├────────┼───────┼───────┼──────────────┼──────────────┼───────┼────────┤
│    gre │     6 │     6 │ inherit 0xe4 │   inherit 81 │ false │     OK │
│    gre │     6 │     6 │ inherit 0xa4 │  inherit 130 │  true │     OK │
│    gre │     6 │     6 │   fixed 0x18 │    fixed 140 │ false │     OK │
│    gre │     6 │     6 │   fixed 0xc8 │    fixed 175 │  true │     OK │
├────────┼───────┼───────┼──────────────┼──────────────┼───────┼────────┤
│    gre │     6 │ other │ inherit 0x74 │  inherit 142 │ false │     OK │
│    gre │     6 │ other │ inherit 0x50 │  inherit 125 │  true │     OK │
│    gre │     6 │ other │   fixed 0x90 │     fixed 84 │ false │     OK │
│    gre │     6 │ other │   fixed 0xb8 │    fixed 240 │  true │     OK │
├────────┼───────┼───────┼──────────────┼──────────────┼───────┼────────┤
│  Type  │ outer | inner │     tos      │      ttl     │  vlan │ result │
├────────┼───────┼───────┼──────────────┼──────────────┼───────┼────────┤
│  vxlan │     4 │     4 │ inherit 0xb4 │   inherit 93 │ false │

Developers usually ask for bash -x output of the script that failed or hung
when reporting problems (too long for an email):

https://domac.alu.unizg.hr/~mtodorov/linux/selftests/net-namespace-20230106/bash-l2_tos_ttl_inherit.html

dmesg might be useful:

https://domac.alu.unizg.hr/~mtodorov/linux/selftests/net-namespace-20230106/dmesg-20230107.txt

Hope this helps.

I am rather new to namespaces, so I can't help more than that with the current
state of my learning curve :)

Thanks,
Mirsad

--
Mirsad Goran Todorovac
Sistem inženjer
Grafički fakultet | Akademija likovnih umjetnosti
Sveučilište u Zagrebu
-- 
System engineer
Faculty of Graphic Arts | Academy of Fine Arts
University of Zagreb, Republic of Croatia
The European Union