From: Jesper Dangaard Brouer <brouer@redhat.com>
To: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
Cc: grygorii.strashko@ti.com, hawk@kernel.org, davem@davemloft.net,
ast@kernel.org, linux-kernel@vger.kernel.org,
linux-omap@vger.kernel.org, xdp-newbies@vger.kernel.org,
ilias.apalodimas@linaro.org, netdev@vger.kernel.org,
daniel@iogearbox.net, jakub.kicinski@netronome.com,
john.fastabend@gmail.com, brouer@redhat.com
Subject: Re: [PATCH net-next 3/3] net: ethernet: ti: cpsw: add XDP support
Date: Wed, 29 May 2019 10:16:59 +0200 [thread overview]
Message-ID: <20190529101659.2aa714b8@carbon> (raw)
In-Reply-To: <20190523182035.9283-4-ivan.khoronzhuk@linaro.org>
On Thu, 23 May 2019 21:20:35 +0300
Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org> wrote:
> +static struct page *cpsw_alloc_page(struct cpsw_common *cpsw)
> +{
> + struct page_pool *pool = cpsw->rx_page_pool;
> + struct page *page, *prev_page = NULL;
> + int try = pool->p.pool_size << 2;
> + int start_free = 0, ret;
> +
> + do {
> + page = page_pool_dev_alloc_pages(pool);
> + if (!page)
> + return NULL;
> +
> + /* if netstack has page_pool recycling remove the rest */
> + if (page_ref_count(page) == 1)
> + break;
> +
> + /* start free pages in use, shouldn't happen */
> + if (prev_page == page || start_free) {
> + /* dma unmap/puts page if rfcnt != 1 */
> + page_pool_recycle_direct(pool, page);
> + start_free = 1;
> + continue;
> + }
> +
> + /* if refcnt > 1, page has been holding by netstack, it's pity,
> + * so put it to the ring to be consumed later when fast cash is
> + * empty. If ring is full then free page by recycling as above.
> + */
> + ret = ptr_ring_produce(&pool->ring, page);
This looks very wrong to me! First of all you are manipulation
directly with the internal pool->ring and not using the API, which
makes this code un-maintainable. Second this is wrong, as page_pool
assume the in-variance that pages on the ring have refcnt==1.
> + if (ret) {
> + page_pool_recycle_direct(pool, page);
> + continue;
> + }
> +
> + if (!prev_page)
> + prev_page = page;
> + } while (try--);
> +
> + return page;
> +}
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
next prev parent reply other threads:[~2019-05-29 8:17 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-23 18:20 [PATCH net-next 0/3] net: ethernet: ti: cpsw: Add XDP support Ivan Khoronzhuk
2019-05-23 18:20 ` [PATCH net-next 1/3] net: ethernet: ti: davinci_cpdma: add dma mapped submit Ivan Khoronzhuk
2019-05-23 18:20 ` [PATCH net-next 2/3] net: ethernet: ti: davinci_cpdma: return handler status Ivan Khoronzhuk
2019-05-23 18:20 ` [PATCH net-next 3/3] net: ethernet: ti: cpsw: add XDP support Ivan Khoronzhuk
2019-05-24 11:05 ` Ilias Apalodimas
2019-05-27 18:21 ` Ivan Khoronzhuk
2019-05-24 11:54 ` Jesper Dangaard Brouer
2019-05-27 18:10 ` Ivan Khoronzhuk
2019-05-24 17:49 ` grygorii
2019-05-27 18:29 ` Ivan Khoronzhuk
2019-05-27 7:17 ` Dan Carpenter
2019-05-29 8:16 ` Jesper Dangaard Brouer [this message]
2019-05-29 9:58 ` Ivan Khoronzhuk
2019-05-24 9:41 ` [PATCH net-next 0/3] net: ethernet: ti: cpsw: Add " Ilias Apalodimas
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