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From:   Alexei Starovoitov <alexei.starovoitov@gmail.com>
Date:   Wed, 19 Feb 2020 08:37:25 -0800
Message-ID: <CAADnVQLhEaV=dWMZC83g5QHit7Qvu4H84Dh--K3aOTiUNeEd4g@mail.gmail.com>
Subject: Re: [PATCH bpf-next 0/6] bpftool: Allow to select sections and filter probes
To:     Michal Rostecki <mrostecki@opensuse.org>
Cc:     bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        Andrii Nakryiko <andriin@fb.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Network Development <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Shuah Khan <shuah@kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>
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On Wed, Feb 19, 2020 at 4:33 AM Michal Rostecki <mrostecki@opensuse.org> wrote:
>
> On 2/19/20 4:02 AM, Alexei Starovoitov wrote:
> > The motivation is clear, but I think the users shouldn't be made
> > aware of such implementation details. I think instead of filter_in/out
> > it's better to do 'full or safe' mode of probing.
> > By default it can do all the probing that doesn't cause
> > extra dmesgs and in 'full' mode it can probe everything.
>
> Alright, then I will send later v2 where the "internal" implementation
> (filtering out based on regex) stays similar (filter_out will stay in
> the code without being exposed to users, filter_in will be removed). And
> the exposed option of "safe" probing will just apply the
> "(trace|write_user)" filter_out pattern. Does it sound good?

yes. If implementation is doing filter_in and applying 'trace_printk|write_user'
strings hidden within bpftool than I think it should be good.
What do you think the default should be?
It feels to me that the default should not be causing dmesg prints.
So only addition flag for bpftool command line will be 'bpftool
feature probe full'