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Date: Mon, 26 Feb 2024 17:25:33 +0000
From: Simon Horman <horms@kernel.org>
To: Julien Panis <jpanis@baylibre.com>
Cc: "David S. Miller" <davem@davemloft.net>,
 Eric Dumazet <edumazet@google.com>,
 Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
 Russell King <linux@armlinux.org.uk>, Alexei Starovoitov <ast@kernel.org>,
 Daniel Borkmann <daniel@iogearbox.net>,
 Jesper Dangaard Brouer <hawk@kernel.org>,
 John Fastabend <john.fastabend@gmail.com>,
 Sumit Semwal <sumit.semwal@linaro.org>,
 Christian =?utf-8?B?S8O2bmln?= <christian.koenig@amd.com>,
 netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
 bpf@vger.kernel.org, linux-media@vger.kernel.org,
 dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org
Subject: Re: [PATCH] net: ethernet: ti: am65-cpsw: Add minimal XDP support
Message-ID: <20240226172533.GG13129@kernel.org>
References: <20240223-am65-cpsw-xdp-basic-v1-1-9f0b6cbda310@baylibre.com>
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On Fri, Feb 23, 2024 at 12:01:37PM +0100, Julien Panis wrote:
> This patch adds XDP (eXpress Data Path) support to TI AM65 CPSW
> Ethernet driver. The following features are implemented:
> - NETDEV_XDP_ACT_BASIC (XDP_PASS, XDP_TX, XDP_DROP, XDP_ABORTED)
> - NETDEV_XDP_ACT_REDIRECT (XDP_REDIRECT)
> - NETDEV_XDP_ACT_NDO_XMIT (ndo_xdp_xmit callback)
> 
> Signed-off-by: Julien Panis <jpanis@baylibre.com>

...

> @@ -440,6 +476,27 @@ static void am65_cpsw_nuss_tx_cleanup(void *data, dma_addr_t desc_dma)
>  	dev_kfree_skb_any(skb);
>  }
>  
> +static struct sk_buff *am65_cpsw_alloc_skb(struct net_device *ndev, unsigned int len)
> +{
> +	struct page *page;
> +	struct sk_buff *skb;

nit: please arrange local variables in reverse xmas tree order,
     from longest line to shortest in new code.

     This tool can be useful: https://github.com/ecree-solarflare/xmastree

> +
> +	page = dev_alloc_pages(0);

nit: Maybe dev_alloc_page() is appropriate here?

> +	if (unlikely(!page))
> +		return NULL;
> +
> +	len += AM65_CPSW_HEADROOM;
> +
> +	skb = build_skb(page_address(page), len);
> +	if (unlikely(!skb))

Does page need to be freed here?

> +		return NULL;
> +
> +	skb_reserve(skb, AM65_CPSW_HEADROOM + NET_IP_ALIGN);
> +	skb->dev = ndev;
> +
> +	return skb;
> +}

...