Date:   Sat, 11 Feb 2023 16:51:20 +0000
From:   Qais Yousef <qyousef@layalina.io>
To:     Yafang Shao <laoar.shao@gmail.com>
Cc:     Kajetan Puchalski <kajetan.puchalski@arm.com>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        John Stultz <jstultz@google.com>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Network Development <netdev@vger.kernel.org>,
        bpf <bpf@vger.kernel.org>,
        "linux-perf-use." <linux-perf-users@vger.kernel.org>,
        Linux-Fsdevel <linux-fsdevel@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        kernel test robot <oliver.sang@intel.com>,
        kbuild test robot <lkp@intel.com>,
        Andrii Nakryiko <andrii@kernel.org>,
        David Hildenbrand <david@redhat.com>,
        Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
        Andrii Nakryiko <andrii.nakryiko@gmail.com>,
        Michal Miroslaw <mirq-linux@rere.qmqm.pl>,
        Peter Zijlstra <peterz@infradead.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Matthew Wilcox <willy@infradead.org>,
        Al Viro <viro@zeniv.linux.org.uk>,
        Kees Cook <keescook@chromium.org>,
        Petr Mladek <pmladek@suse.com>,
        Lukasz Luba <lukasz.luba@arm.com>,
        Qais Yousef <qyousef@google.com>,
        Daniele Di Proietto <ddiproietto@google.com>
Subject: Re: [PATCH v2 7/7] tools/testing/selftests/bpf: replace open-coded
 16 with TASK_COMM_LEN
Message-ID: <20230211165120.byivmbfhwyegiyae@airbuntu>
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 <08e1c9d0-376f-d669-6fe8-559b2fbc2f2b@efficios.com>
 <CALOAHbBsmajStJ8TrnqEL_pv=UOt-vv0CH30EqThVq=JYXfi8A@mail.gmail.com>
 <Y+UCxSktKM0CzMlA@e126311.manchester.arm.com>
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On 02/09/23 23:37, Yafang Shao wrote:
> On Thu, Feb 9, 2023 at 10:28 PM Kajetan Puchalski
> <kajetan.puchalski@arm.com> wrote:
> >
> > On Thu, Feb 09, 2023 at 02:20:36PM +0800, Yafang Shao wrote:
> >
> > [...]
> >
> > Hi Yafang,
> >
> > > Many thanks for the detailed analysis. Seems it can work.
> > >
> > > Hi John,
> > >
> > > Could you pls. try the attached fix ? I have verified it in my test env.
> >
> > I tested the patch on my environment where I found the issue with newer
> > kernels + older Perfetto. The patch does improve things so that's nice.
> 
> Thanks for the test. I don't have Perfetto in hand, so I haven't
> verify Perfetto.

FWIW, perfetto is not android specific and can run on normal linux distro setup
(which I do but haven't noticed this breakage).

It's easy to download the latest release (including for android though I never
tried that) from github

	https://github.com/google/perfetto/releases

Kajetan might try to see if he can pick the latest version which IIUC contains
a workaround.

If this simple patch can be tweaked to make it work again against older
versions that'd be nice though.

HTH.


Cheers

--
Qais Yousef