From: Jesper Dangaard Brouer <brouer@redhat•com>
To: Ivan Khoronzhuk <ivan.khoronzhuk@linaro•org>
Cc: grygorii.strashko@ti•com, 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, Tariq Toukan <tariqt@mellanox•com>
Subject: Re: [PATCH net-next 3/3] net: ethernet: ti: cpsw: add XDP support
Date: Fri, 24 May 2019 13:54:18 +0200 [thread overview]
Message-ID: <20190524135418.5408591e@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:
> Add XDP support based on rx page_pool allocator, one frame per page.
> Page pool allocator is used with assumption that only one rx_handler
> is running simultaneously. DMA map/unmap is reused from page pool
> despite there is no need to map whole page.
When using page_pool for DMA-mapping, your XDP-memory model must use
1-page per packet, which you state you do. This is because
__page_pool_put_page() fallback mode does a __page_pool_clean_page()
unmapping the DMA. Ilias and I are looking at options for removing this
restriction as Mlx5 would need it (when we extend the SKB to return
pages to page_pool).
Unfortunately, I've found another blocker for drivers using the DMA
mapping feature of page_pool. We don't properly handle the case, where
a remote TX-driver have xdp_frame's in-flight, and simultaneously the
sending driver is unloaded and take down the page_pool. Nothing crash,
but we end-up calling put_page() on a page that is still DMA-mapped.
I'm working on different solutions for fixing this, see here:
https://github.com/xdp-project/xdp-project/blob/master/areas/mem/page_pool03_shutdown_inflight.org
--
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:[~2019-05-24 11:54 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 [this message]
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
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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