linux-kernel - Re: [PATCH] bpf: remove redundant null pointer check before consume

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Message-ID: <CAPhsuW47a=6r_O9WRp=BrpOfDfKFFrzvfmdsuAUygZYZXP4sFg@mail.gmail.com>
Date:   Thu, 20 Sep 2018 10:53:59 -0700
From:   Song Liu <liu.song.a23@...il.com>
To:     zhongjiang@...wei.com
Cc:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Networking <netdev@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] bpf: remove redundant null pointer check before consume_skb

On Thu, Sep 20, 2018 at 3:00 AM zhong jiang <zhongjiang@...wei.com> wrote:
>
> consume_skb has taken the null pointer into account. hence it is safe
> to remove the redundant null pointer check before consume_skb.
>
> Signed-off-by: zhong jiang <zhongjiang@...wei.com>

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

> ---
>  kernel/bpf/sockmap.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
> index 488ef96..a9359cb 100644
> --- a/kernel/bpf/sockmap.c
> +++ b/kernel/bpf/sockmap.c
> @@ -590,8 +590,7 @@ static int free_sg(struct sock *sk, int start,
>                 if (i == MAX_SKB_FRAGS)
>                         i = 0;
>         }
> -       if (md->skb)
> -               consume_skb(md->skb);
> +       consume_skb(md->skb);
>
>         return free;
>  }
> @@ -973,8 +972,7 @@ static int bpf_tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
>
>                 if (!sg->length && md->sg_start == md->sg_end) {
>                         list_del(&md->list);
> -                       if (md->skb)
> -                               consume_skb(md->skb);
> +                       consume_skb(md->skb);
>                         kfree(md);
>                 }
>         }
> --
> 1.7.12.4
>