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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Thu, 31 Mar 2022 23:41:34 +0900
Message-ID: <CAK7LNAR_2jJWJbaUfLDaDJOuJTx_RHj_Ow5coK1k4Y5HGLRQrA@mail.gmail.com>
Subject: Re: [PATCH] tracing: do not export user_events uapi
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Beau Belgrave <beaub@linux.microsoft.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        linux-trace-devel <linux-trace-devel@vger.kernel.org>,
        bpf <bpf@vger.kernel.org>,
        Network Development <netdev@vger.kernel.org>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Michal Marek <michal.lkml@markovi.net>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>
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On Thu, Mar 31, 2022 at 9:13 PM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Thu, 31 Mar 2022 16:29:30 +0900
> Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> > Well, the intended usage of no-export-headers is to
> > cater to the UAPI supported by only some architectures.
> > We have kvm(_para).h here because not all architectures
> > support kvm.
> >
> > If you do not want to export the UAPI,
> > you should not put it in include/uapi/.
> >
> > After the API is finalized, you can move it to
> > include/uapi.
>
> So a little bit of background. I and a few others thought it was done, and
> pushed it to Linus. Then when it made it into his tree (and mentioned on
> LWN) it got a wider audience that had concerns. After they brought up those
> concerns, we agreed that this needs a bit more work. I was hoping not to do
> a full revert and simply marked the change for broken so that it can be
> worked on upstream with the wider audience. Linus appears to be fine with
> this approach, as he helped me with my "mark for BROKEN" patch.
>
> Mathieu's concern is that this header file could be used in older distros
> with newer kernels that have it implemented and added this to keep out of
> those older distros.
>
> The options to make Mathieu sleep better at night are:
>
> 1) this patch
>
> 2) move this file out of uapi.
>
> 3) revert the entire thing.
>
> I really do not want to do #3 but I am willing to do 1 or 2.

I see.

Either 1 or 2 is OK
if  you are sure this will be fixed sooner or later.


-- 
Best Regards
Masahiro Yamada