From: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
To: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: grygorii.strashko@ti.com, linux-omap@vger.kernel.org,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
hawk@kernel.org, xdp-newbies@vger.kernel.org, ast@kernel.org,
aniel@iogearbox.net, jakub.kicinski@netronome.com,
john.fastabend@gmail.com
Subject: Re: [RFC PATCH 3/3] net: ethernet: ti: cpsw: add XDP support
Date: Fri, 19 Apr 2019 13:42:30 +0300 [thread overview]
Message-ID: <20190419104228.GA4268@khorivan> (raw)
In-Reply-To: <20190419083156.GA6687@apalos>
On Fri, Apr 19, 2019 at 11:31:56AM +0300, Ilias Apalodimas wrote:
>Hi Ivan,
>
>> +static struct page *cpsw_alloc_page(struct cpsw_common *cpsw)
>> +{
>> + struct page_pool *pool = cpsw->rx_page_pool;
>> + struct page *page;
>> + int i = 0;
>> +
>> + do {
>> + page = page_pool_dev_alloc_pages(pool);
>> + if (!page)
>> + return NULL;
>> +
>> + /* skip pages used by skb netstack */
>I think the comment here is wrong and might confuse people.
>The page ref cnt is 1, which means the packet was *processed* and netstack is
>done with it, hence you can re-use it.
>If it's !=1 then you correctly unmap the buffer and decrease the ref cnt, so it
>will eventually be freed and not returned to the pool, right?
It's compensation substitution for page_pool support in skb netsack.
And should be considered in combine with:
skb = build_skb(xmeta, cpsw_rxbuf_total_len(pkt_size));
...
page_pool_recycle_direct(pool, page);
page_ref_inc(page);
netif_receive_skb(skb);
Here order is important.
I will correct comments in final version (w/o overloading) ofc, leaving
thinking environment for people. I think it's fair enough about this.
>> + if (page_ref_count(page) == 1)
>> + break;
>> +
>> + /* it's a pitty, but free page */
>> + page_pool_recycle_direct(pool, page);
>> + } while (++i < descs_pool_size);
>> +
>> + return page;
>> +}
>> +
>
> /Ilias
--
Regards,
Ivan Khoronzhuk
next prev parent reply other threads:[~2019-04-19 19:32 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-17 17:49 [RFC PATCH 0/3] net: ethernet: ti: cpsw: Add XDP support Ivan Khoronzhuk
2019-04-17 17:49 ` [RFC PATCH 1/3] net: ethernet: ti: davinci_cpdma: add dma mapped submit Ivan Khoronzhuk
2019-04-17 17:49 ` [RFC PATCH 2/3] net: ethernet: ti: davinci_cpdma: return handler status Ivan Khoronzhuk
2019-04-17 17:49 ` [RFC PATCH 3/3] net: ethernet: ti: cpsw: add XDP support Ivan Khoronzhuk
2019-04-17 22:46 ` Jakub Kicinski
2019-04-18 9:40 ` Ivan Khoronzhuk
2019-04-18 17:41 ` Jakub Kicinski
2019-04-18 18:30 ` Ivan Khoronzhuk
2019-04-18 18:44 ` Jakub Kicinski
2019-04-19 8:31 ` Ilias Apalodimas
2019-04-19 10:42 ` Ivan Khoronzhuk [this message]
2019-04-18 6:12 ` [RFC PATCH 0/3] net: ethernet: ti: cpsw: Add " Björn Töpel
2019-04-18 9:47 ` Ivan Khoronzhuk
2019-04-19 8:24 ` Grygorii Strashko
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