netdev - Re: [PATCH bpf-next] libbpf: add retries in sys_bpf_prog

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Message-ID: <CAKH8qBvubA9RyqCrnRP2nahzZb8jpux+VbmbFdBoXh14SR3BMQ@mail.gmail.com>
Date:   Wed, 2 Dec 2020 14:51:25 -0800
From:   Stanislav Fomichev <sdf@...gle.com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>
Subject: Re: [PATCH bpf-next] libbpf: add retries in sys_bpf_prog_load

On Wed, Dec 2, 2020 at 2:46 PM Andrii Nakryiko
<andrii.nakryiko@...il.com> wrote:
>
> On Wed, Dec 2, 2020 at 9:52 AM Stanislav Fomichev <sdf@...gle.com> wrote:
> >
> > I've seen a situation, where a process that's under pprof constantly
> > generates SIGPROF which prevents program loading indefinitely.
> > The right thing to do probably is to disable signals in the upper
> > layers while loading, but it still would be nice to get some error from
> > libbpf instead of an endless loop.
> >
> > Let's add some small retry limit to the program loading:
> > try loading the program 10 (arbitrary) times and give up.
> >
> > Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
> > ---
>
> The subject is misleading as hell. You are not adding retries, you are
> limiting the number of retries.
Ah, sorry, should've been s/add/cap/ :-(

> Otherwise, LGTM. I'd probably go with an even smaller number, can't
> imagine any normal use case having more than once EAGAIN. So I'd say
> feel free to reduce it to 5 even.
>
> Acked-by: Andrii Nakryiko <andrii@...nel.org>
Let me respin with a proper subject and 5 retries.