linux-kernel - Re: [PATCH net-next] tools: Fix MSG_SPLICE

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Message-ID: <5791ec06-7174-9ae5-4fe4-6969ed110165@tessares.net>
Date:   Mon, 26 Jun 2023 15:47:00 +0200
From:   Matthieu Baerts <matthieu.baerts@...sares.net>
To:     David Howells <dhowells@...hat.com>, netdev@...r.kernel.org
Cc:     Arnaldo Carvalho de Melo <acme@...hat.com>,
        David Miller <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, Jens Axboe <axboe@...nel.dk>,
        Matthew Wilcox <willy@...radead.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        linux-perf-users@...r.kernel.org, bpf@...r.kernel.org,
        linux-next@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] tools: Fix MSG_SPLICE_PAGES build error in trace
 tools

Hi David,

Thank you for the patch!

On 26/06/2023 15:20, David Howells wrote:
> The following error is being seen the perf tools because they have their
> own copies of a lot of kernel headers:
> 
> In file included from builtin-trace.c:907:
> trace/beauty/msg_flags.c: In function 'syscall_arg__scnprintf_msg_flags':
> trace/beauty/msg_flags.c:28:21: error: 'MSG_SPLICE_PAGES' undeclared (first use in this function)
>    28 |         if (flags & MSG_##n) { \
>       |                     ^~~~
> trace/beauty/msg_flags.c:50:9: note: in expansion of macro 'P_MSG_FLAG'
>    50 |         P_MSG_FLAG(SPLICE_PAGES);
>       |         ^~~~~~~~~~
> trace/beauty/msg_flags.c:28:21: note: each undeclared identifier is reported only once for each function it appears in
>    28 |         if (flags & MSG_##n) { \
>       |                     ^~~~
> trace/beauty/msg_flags.c:50:9: note: in expansion of macro 'P_MSG_FLAG'
>    50 |         P_MSG_FLAG(SPLICE_PAGES);
>       |         ^~~~~~~~~~
> 
> Fix this by (1) adding MSG_SPLICE_PAGES to
> tools/perf/trace/beauty/include/linux/socket.h - which looks like it ought
> to work, but doesn't

Commit 58277f502f42 ("perf trace beauty: Add script to autogenerate
socket families table") seems to suggest this file is only used by
tools/perf/trace/beauty/socket.sh script (and later by sockaddr.sh) but
not by msg_flags.c.

If I'm not mistaken, it is then not required to modify this file to fix
the issue you mention.

But it is still needed to modify it to avoid another warning:

  Warning: Kernel ABI header at
'tools/perf/trace/beauty/include/linux/socket.h' differs from latest
version at 'include/linux/socket.h'
  diff -u tools/perf/trace/beauty/include/linux/socket.h
include/linux/socket.h
So another issue. When checking the differences between the two files, I
see there are still also other modifications to import, e.g. it looks
like you also added MSG_INTERNAL_SENDMSG_FLAGS macro in socket.h. Do you
plan to fix that too?
It might be clearer to have all these modifications of
tools/perf/trace/beauty/include/linux/socket.h in a separated commit as
it is fixing a different issue but that's a detail. As long as we can
have perf compiling without issues when using the net-next tree :)

Cheers,
Matt
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