netdev - Re: [RFC PATCH] bpf: Fix potential call bpf_link

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Message-ID: <CAPhsuW7W0Cm_eyEY8pDGwMqo8pM3OWAUYUu8PyUqcUxPGLX3DA@mail.gmail.com>
Date:   Thu, 17 Sep 2020 15:37:10 -0700
From:   Song Liu <song@...nel.org>
To:     Muchun Song <songmuchun@...edance.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>
Subject: Re: [RFC PATCH] bpf: Fix potential call bpf_link_free() in atomic context

On Thu, Sep 17, 2020 at 12:46 AM Muchun Song <songmuchun@...edance.com> wrote:
>
> The in_atomic macro cannot always detect atomic context. In particular,
> it cannot know about held spinlocks in non-preemptible kernels. Although,
> there is no user call bpf_link_put() with holding spinlock now. Be the
> safe side, we can avoid this in the feature.
>
> Signed-off-by: Muchun Song <songmuchun@...edance.com>

Acked-by: Song Liu <songliubraving@...com>

This is a little weird, but I guess that is OK, as bpf_link_put() is
not in the critical
path. Is the plan to eliminate in_atomic() (as much as possible)?