Re: [PATCH] net: exit immediately when off = 0 in skb_headers_offset_update()

[Eric Dumazet]

On Thu, Aug 27, 2020 at 4:25 AM Miaohe Lin <linmiaohe@xxxxxxxxxx> wrote:
>
> In the case of off = 0, skb_headers_offset_update() do nothing indeed.
>
> Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
> ---
>  net/core/skbuff.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 18ed56316e56..f67f0da20a5b 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -1459,6 +1459,8 @@ EXPORT_SYMBOL(skb_clone);
>
>  void skb_headers_offset_update(struct sk_buff *skb, int off)
>  {
> +       if (unlikely(off == 0))
> +               return;

If this is unlikely, I doubt adding a test is going to save anything.

This will instead add a conditional test for the 'likely' cases.