Message-ID: <CAJwJo6bMxTC8BJaHWy1AfMJ-CLPvn67qfkS0cZYr7TuhgHH-6A@mail.gmail.com>
Date: Mon, 19 Aug 2024 18:19:21 +0100
From: Dmitry Safonov <0x7f454c46@...il.com>
To: 0x7f454c46@...il.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>, 
	Mohammad Nassiri <mnassiri@...na.com>, netdev@...r.kernel.org, 
	linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v3 0/8] net/selftests: TCP-AO selftests updates

Going to update with v4, I see some netdev failures on non-appeared
trace events.
I need to review the synchronization on the tracer thread.

pw-bot: changes-requested

On Thu, 15 Aug 2024 at 22:32, Dmitry Safonov via B4 Relay
<devnull+0x7f454c46.gmail.com@...nel.org> wrote:
>
> First 3 patches are more-or-less cleanups/preparations.
>
> Patches 4/5 are fixes for netns file descriptors leaks/open.
>
> Patch 6 was sent to me/contributed off-list by Mohammad, who wants 32-bit
> kernels to run TCP-AO.
>
> Patch 7 is a workaround/fix for slow VMs. Albeit, I can't reproduce
> the issue, but I hope it will fix netdev flakes for connect-deny-*
> tests.
>
> And the biggest change is adding TCP-AO tracepoints to selftests.
> I think it's a good addition by the following reasons:
> - The related tracepoints are now tested;
> - It allows tcp-ao selftests to raise expectations on the kernel
>   behavior - up from the syscalls exit statuses + net counters.
> - Provides tracepoints usage samples.
>
> As tracepoints are not a stable ABI, any kernel changes done to them
> will be reflected to the selftests, which also will allow users
> to see how to change their code. It's quite better than parsing dmesg
> (what BGP was doing pre-tracepoints, ugh).
>
> Somewhat arguably, the code parses trace_pipe, rather than uses
> libtraceevent (which any sane user should do). The reason behind that is
> the same as for rt-netlink macros instead of libmnl: I'm trying
> to minimize the library dependencies of the selftests. And the
> performance of formatting text in kernel and parsing it again in a test
> is not critical.
>
> Current output sample:
> > ok 73 Trace events matched expectations: 13 tcp_hash_md5_required[2] tcp_hash_md5_unexpected[4] tcp_hash_ao_required[3] tcp_ao_key_not_found[4]
>
> Previously, tracepoints selftests were part of kernel tcp tracepoints
> submission [1], but since then the code was quite changed:
> - Now generic tracing setup is in lib/ftrace.c, separate from
>   lib/ftrace-tcp.c which utilizes TCP trace points. This separation
>   allows future selftests to trace non-TCP events, i.e. to find out
>   an skb's drop reason, which was useful in the creation of TCP-CLOSE
>   stress-test (not in this patch set, but used in attempt to reproduce
>   the issue from [2]).
> - Another change is that in the previous submission the trace events
>   where used only to detect unexpected TCP-AO/TCP-MD5 events. In this
>   version the selftests will fail if an expected trace event didn't
>   appear.
>   Let's see how reliable this is on the netdev bot - it obviously passes
>   on my testing, but potentially may require a temporary XFAIL patch
>   if it misbehaves on a slow VM.
>
> [1] https://lore.kernel.org/lkml/20240224-tcp-ao-tracepoints-v1-0-15f31b7f30a7@arista.com/
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net.git/commit/?id=33700a0c9b56
>
> Signed-off-by: Dmitry Safonov <0x7f454c46@...il.com>
[..]

Sorry for the noise,
             Dmitry

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