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

[luyun <luyun_611@163.com>]

在 2026/7/6 21:55, Willem de Bruijn 写道:
> 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.

Thanks for your review.

The skb_zcopy() does indeed make repeated checks. So following your 
suggestion,

I have modified the code as follows:

-                       net_zcopy_get(skb_zcopy(skb));
+                       net_zcopy_get(skb_uarg(skb));

Does it seem more reasonable?

And I plan to modify all three functions in patch version 2.