Re: [PATCH net-next] net: skbuff: use net_zcopy_get() instead of refcount_inc()

[Willem de Bruijn <willemdebruijn.kernel@gmail.com>]

Yun Lu wrote:
> From: Yun Lu <luyun@kylinos.cn>
> 
> The net_zcopy_get() increments the uarg->refcnt, which is called both
> in pskb_carve_inside_header() and pskb_carve_inside_nonlinear().
> Also use net_zcopy_get() in pskb_expand_head for code consistency.
> 
> No functional change intended.
> 
> Signed-off-by: Yun Lu <luyun@kylinos.cn>
> ---
>  net/core/skbuff.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index 18dabb4e9cfa..bcf3b2c65fb9 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -2326,7 +2326,7 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
>  		if (skb_orphan_frags(skb, gfp_mask))
>  			goto nofrags;
>  		if (skb_zcopy(skb))
> -			refcount_inc(&skb_uarg(skb)->refcnt);
> +			net_zcopy_get(skb_zcopy(skb));

This adds some unnecessary instructions in skb_zcopy.

It's not terrible and I see the consistency argument. But would make
more sense to update the recently added pskb_carve_.. variants instead.