netdev - Re: [PATCH net] bpf: fix u64_stats_init() usage in bpf_prog

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Date:   Fri, 1 Mar 2019 15:31:11 -0800
From:   Song Liu <liu.song.a23@...il.com>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        netdev <netdev@...r.kernel.org>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        bpf <bpf@...r.kernel.org>, Guenter Roeck <linux@...ck-us.net>
Subject: Re: [PATCH net] bpf: fix u64_stats_init() usage in bpf_prog_alloc()

On Fri, Mar 1, 2019 at 2:34 PM Eric Dumazet <edumazet@...gle.com> wrote:
>
> We need to iterate through all possible cpus.
>
> Fixes: 492ecee892c2 ("bpf: enable program stats")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Reported-by: Guenter Roeck <linux@...ck-us.net>
> Tested-by: Guenter Roeck <linux@...ck-us.net>

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

> ---
>  kernel/bpf/core.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> index 1c14c347f3cfe1f7c0cf8a7eccff8135b16df81f..3f08c257858e1570339cd64a6351824bcc332ee3 100644
> --- a/kernel/bpf/core.c
> +++ b/kernel/bpf/core.c
> @@ -109,6 +109,7 @@ struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags)
>  {
>         gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO | gfp_extra_flags;
>         struct bpf_prog *prog;
> +       int cpu;
>
>         prog = bpf_prog_alloc_no_stats(size, gfp_extra_flags);
>         if (!prog)
> @@ -121,7 +122,12 @@ struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags)
>                 return NULL;
>         }
>
> -       u64_stats_init(&prog->aux->stats->syncp);
> +       for_each_possible_cpu(cpu) {
> +               struct bpf_prog_stats *pstats;
> +
> +               pstats = per_cpu_ptr(prog->aux->stats, cpu);
> +               u64_stats_init(&pstats->syncp);
> +       }
>         return prog;
>  }
>  EXPORT_SYMBOL_GPL(bpf_prog_alloc);
> --
> 2.21.0.352.gf09ad66450-goog
>