netdev - Re: [PATCH 10/18] bpf: Re-initialize lnode in bpf_ksym

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Message-ID: <CAPhsuW7B9cH+593sA8hfCEziGcxyxvT9iMx8NYHZKnOUxkR8rg@mail.gmail.com>
Date:   Wed, 26 Feb 2020 15:21:36 -0800
From:   Song Liu <song@...nel.org>
To:     Jiri Olsa <jolsa@...nel.org>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        Andrii Nakryiko <andriin@...com>, Yonghong Song <yhs@...com>,
        Song Liu <songliubraving@...com>,
        Martin KaFai Lau <kafai@...com>,
        Jakub Kicinski <kuba@...nel.org>,
        David Miller <davem@...hat.com>,
        Björn Töpel <bjorn.topel@...el.com>,
        John Fastabend <john.fastabend@...il.com>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH 10/18] bpf: Re-initialize lnode in bpf_ksym_del

On Wed, Feb 26, 2020 at 5:06 AM Jiri Olsa <jolsa@...nel.org> wrote:
>
> When bpf_prog is removed from kallsyms it's on the way
> out to be removed, so we don't care about lnode state.
>
> However the bpf_ksym_del will be used also by bpf_trampoline
> and bpf_dispatcher objects, which stay allocated even when
> they are not in kallsyms list, hence the lnode re-init.
>
> The list_del_rcu commentary states that we need to call
> synchronize_rcu, before we can change/re-init the list_head
> pointers.
>
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>

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