Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20210328161055.257504-1-pctammela@mojatatu.com>
 <CAEf4BzZ+O3x9AksV6MGuicDQO+gObFCQQR7t6UK=RBhuSbOiZg@mail.gmail.com> <CAKY_9u0CQHmzA3YMWw24w-NbH8CK3d7Nt-jaB4EoyN7pK_fJUA@mail.gmail.com>
In-Reply-To: <CAKY_9u0CQHmzA3YMWw24w-NbH8CK3d7Nt-jaB4EoyN7pK_fJUA@mail.gmail.com>
From:   Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date:   Sat, 3 Apr 2021 08:51:16 -0700
Message-ID: <CAEf4BzYp+y_FqSpvdmskuWipJLX=Bp1rUEAnB0vsV-5sYXv8ww@mail.gmail.com>
Subject: Re: [PATCH bpf-next] bpf: add 'BPF_RB_MAY_WAKEUP' flag
To:     Pedro Tammela <pctammela@gmail.com>
Cc:     Pedro Tammela <pctammela@mojatatu.com>,
        Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        Martin KaFai Lau <kafai@fb.com>,
        Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
        John Fastabend <john.fastabend@gmail.com>,
        KP Singh <kpsingh@kernel.org>, Shuah Khan <shuah@kernel.org>,
        Joe Stringer <joe@cilium.io>,
        Quentin Monnet <quentin@isovalent.com>,
        Yang Li <yang.lee@linux.alibaba.com>,
        Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Sat, Apr 3, 2021 at 6:34 AM Pedro Tammela <pctammela@gmail.com> wrote:
>
> Em qua., 31 de mar. de 2021 =C3=A0s 03:54, Andrii Nakryiko
> <andrii.nakryiko@gmail.com> escreveu:
> >
> > On Sun, Mar 28, 2021 at 9:11 AM Pedro Tammela <pctammela@gmail.com> wro=
te:
> > >
> > > The current way to provide a no-op flag to 'bpf_ringbuf_submit()',
> > > 'bpf_ringbuf_discard()' and 'bpf_ringbuf_output()' is to provide a '0=
'
> > > value.
> > >
> > > A '0' value might notify the consumer if it already caught up in proc=
essing,
> > > so let's provide a more descriptive notation for this value.
> > >
> > > Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
> > > ---
> >
> > flags =3D=3D 0 means "no extra modifiers of behavior". That's default
> > adaptive notification. If you want to adjust default behavior, only
> > then you specify non-zero flags. I don't think anyone will bother
> > typing BPF_RB_MAY_WAKEUP for this, nor I think it's really needed. The
> > documentation update is nice (if no flags are specified notification
> > will be sent if needed), but the new "pseudo-flag" seems like an
> > overkill to me.
>
> My intention here is to make '0' more descriptive.
> But if you think just the documentation update is enough, then I will
> remove the flag.

flags =3D=3D 0 means "default behavior", I don't think you have to
remember which verbose flag you need to specify for that, so I think
just expanding documentation is sufficient and better. Thanks!

>
> >
> > >  include/uapi/linux/bpf.h                               | 8 ++++++++
> > >  tools/include/uapi/linux/bpf.h                         | 8 ++++++++
> > >  tools/testing/selftests/bpf/progs/ima.c                | 2 +-
> > >  tools/testing/selftests/bpf/progs/ringbuf_bench.c      | 2 +-
> > >  tools/testing/selftests/bpf/progs/test_ringbuf.c       | 2 +-
> > >  tools/testing/selftests/bpf/progs/test_ringbuf_multi.c | 2 +-
> > >  6 files changed, 20 insertions(+), 4 deletions(-)
> > >
> >
> > [...]