Re: [PATCH net-next 07/12] xsk: add generic XSk &xdp_buff -> skb conversion

[Alexander Lobakin]

From: Jakub Kicinski <kuba@xxxxxxxxxx>
Date: Thu, 12 Dec 2024 18:19:44 -0800

> On Wed, 11 Dec 2024 18:26:44 +0100 Alexander Lobakin wrote:
>> +#else /* !CONFIG_PAGE_POOL */
>> +	struct napi_struct *napi;
>> +
>> +	pp = NULL;
>> +	napi = napi_by_id(rxq->napi_id);
>> +	if (likely(napi))
>> +		skb = napi_alloc_skb(napi, len);
>> +	else
>> +		skb = __netdev_alloc_skb_ip_align(rxq->dev, len,
>> +						  GFP_ATOMIC | __GFP_NOWARN);
>> +	if (unlikely(!skb))
>> +		return NULL;
>> +#endif /* !CONFIG_PAGE_POOL */
> 
> What are the chances of having a driver with AF_XDP support 
> and without page pool support? I think it's zero :S

Right, as CONFIG_BPF_SYSCALL selects PAGE_POOL if NET.

I think I wrote this when it wasn't true (before Lorenzo introduced
generic page_pools) and then just forgot to change that ._.

> Can we kill all the if !CONFIG_PAGE_POOL sections and hide
> the entire helper under if CONFIG_PAGE_POLL ?

We can. But I think I'd need to introduce a return-NULL wrapper in case
of !PAGE_POOL to satisfy the linker, as lots of drivers build their XSk
code unconditionally.

Thanks,
Olek