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Date:   Fri, 4 Jun 2021 11:42:17 +0300
From:   Ilias Apalodimas <ilias.apalodimas@linaro.org>
To:     Yunsheng Lin <linyunsheng@huawei.com>
Cc:     Matteo Croce <mcroce@linux.microsoft.com>, netdev@vger.kernel.org,
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        Sven Auhagen <sven.auhagen@voleatech.de>
Subject: Re: [PATCH net-next v6 3/5] page_pool: Allow drivers to hint on SKB
 recycling
Message-ID: <YLnnaRLMlnm+LKwX@iliass-mbp>
References: <20210521161527.34607-1-mcroce@linux.microsoft.com>
 <20210521161527.34607-4-mcroce@linux.microsoft.com>
 <badedf51-ce74-061d-732c-61d0678180b3@huawei.com>
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In-Reply-To: <badedf51-ce74-061d-732c-61d0678180b3@huawei.com>
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[...]
> > +	/* 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.
> > +	 */
> 
> I am not sure I understand how does the last part of comment related
> to the code below, as there is no driver using split-page memory model
> will reach here because those driver will not call skb_mark_for_recycle(),
> right?
> 

Yes the comment is there to prohibit people (mlx5 only actually) to add the
recycling bit on their driver.  Because if they do it will *probably* work
but they might get random corrupted packets which will be hard to debug.

> > +	page->pp = NULL;
> > +	page_pool_put_full_page(pp, virt_to_head_page(data), false);
> > +
> > +	return true;
> > +}
> > +EXPORT_SYMBOL(page_pool_return_skb_page);
>