linux-kernel - Re: [PATCH net-next 2/9] net: skbuff: don't include <net/page

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Message-ID: <61965a16-55bf-2f81-8938-856f834d35bf@intel.com>
Date:   Tue, 1 Aug 2023 15:25:38 +0200
From:   Alexander Lobakin <aleksander.lobakin@...el.com>
To:     Yunsheng Lin <linyunsheng@...wei.com>
CC:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
        Larysa Zaremba <larysa.zaremba@...el.com>,
        Alexander Duyck <alexanderduyck@...com>,
        Jesper Dangaard Brouer <hawk@...nel.org>,
        "Ilias Apalodimas" <ilias.apalodimas@...aro.org>,
        Simon Horman <simon.horman@...igine.com>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net-next 2/9] net: skbuff: don't include
 <net/page_pool/types.h> to <linux/skbuff.h>

From: Yunsheng Lin <linyunsheng@...wei.com>
Date: Sat, 29 Jul 2023 19:40:19 +0800

> On 2023/7/28 21:58, Alexander Lobakin wrote:
>> From: Yunsheng Lin <linyunsheng@...wei.com>
>> Date: Fri, 28 Jul 2023 20:02:51 +0800
>>
>>> On 2023/7/27 22:43, Alexander Lobakin wrote:
>>>> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
>>>
>>> ...
>>>
>>>> +bool page_pool_return_skb_page(struct page *page, bool napi_safe)
>>>
>>> Still having the 'page_pool_' prefix seems odd here when it is in the
>>> skbuff.c where most have skb_ or napi_ prefix, is it better to rename
>>> it to something like napi_return_page_pool_page()?
>>
>> Given that how the function that goes next is named, maybe
>> skb_pp_return_page() (or skb_pp_put_page())?
> 
> skb_pp_put_page() seems better.
> 
> And I like napi_pp_put_page() with 'napi_' prefix better as
> it does not take a skb as parameter and the naming is aligned
> with the 'napi_safe' parameter.

Ah, I see. Sounds reasonable. I'll pick napi_pp_put_page() for the next
round, I like this one.

> 
>>
>>>
>>>> +{
>>>> +	struct napi_struct *napi;
>>>> +	struct page_pool *pp;
>>>> +	bool allow_direct;
>>>> +
>>>> +	page = compound_head(page);
>>>> +
>>>> +	/* page->pp_magic is OR'ed with PP_SIGNATURE after the allocation
>>>> +	 * in order to preserve any existing bits, such as bit 0 for the
>>>> +	 * head page of compound page and bit 1 for pfmemalloc page, so
>>>> +	 * mask those bits for freeing side when doing below checking,
>>>> +	 * and page_is_pfmemalloc() is checked in __page_pool_put_page()
>>>> +	 * to avoid recycling the pfmemalloc page.
>>>> +	 */
>>>> +	if (unlikely((page->pp_magic & ~0x3UL) != PP_SIGNATURE))
>>>> +		return false;
>>>> +
>>>> +	pp = page->pp;
>>>> +
>>>> +	/* Allow direct recycle if we have reasons to believe that we are
>>>> +	 * in the same context as the consumer would run, so there's
>>>> +	 * no possible race.
>>>> +	 */
>>>> +	napi = READ_ONCE(pp->p.napi);
>>>> +	allow_direct = napi_safe && napi &&
>>>> +		READ_ONCE(napi->list_owner) == smp_processor_id();
>>>> +
>>>> +	/* Driver set this to memory recycling info. Reset it on recycle.
>>>> +	 * This will *not* work for NIC using a split-page memory model.
>>>> +	 * The page will be returned to the pool here regardless of the
>>>> +	 * 'flipped' fragment being in use or not.
>>>> +	 */
>>>> +	page_pool_put_full_page(pp, page, allow_direct);
>>>> +
>>>> +	return true;
>>>> +}
>>>> +EXPORT_SYMBOL(page_pool_return_skb_page);
>>>> +
>>>>  static bool skb_pp_recycle(struct sk_buff *skb, void *data, bool napi_safe)
>>
>> (this one)
>>
>>>>  {
>>>>  	if (!IS_ENABLED(CONFIG_PAGE_POOL) || !skb->pp_recycle)
> 
> We may need the 'IS_ENABLED(CONFIG_PAGE_POOL' checking in the newly
> moved function too.

The first person who noticed this, for sure we should have it!

> 
>>>>
>>
>> Thanks,
>> Olek
>>
>> .
>>

Thanks,
Olek