netdev - Re: [PATCH v6 2/4] net: moxa: replace build_skb() with netdev_alloc_skb_ip

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4449672.aCJ5J5rv4r@wuerfel>
Date:	Tue, 26 Aug 2014 11:04:30 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	linux-arm-kernel@...ts.infradead.org
Cc:	Jonas Jensen <jonas.jensen@...il.com>, netdev@...r.kernel.org,
	f.fainelli@...il.com, eric.dumazet@...il.com,
	linux-kernel@...r.kernel.org, mirqus@...il.com, davem@...emloft.net
Subject: Re: [PATCH v6 2/4] net: moxa: replace build_skb() with netdev_alloc_skb_ip_align() / memcpy()

On Monday 25 August 2014 16:22:22 Jonas Jensen wrote:
> @@ -226,13 +226,15 @@ static int moxart_rx_poll(struct napi_struct *napi, int budget)
>                 if (len > RX_BUF_SIZE)
>                         len = RX_BUF_SIZE;
>  
> -               skb = build_skb(priv->rx_buf[rx_head], priv->rx_buf_size);
> +               skb = netdev_alloc_skb_ip_align(ndev, len);
> +
>                 if (unlikely(!skb)) {
> -                       net_dbg_ratelimited("build_skb failed\n");
> +                       net_dbg_ratelimited("netdev_alloc_skb_ip_align failed\n");
>                         priv->stats.rx_dropped++;
>                         priv->stats.rx_errors++;
>                 }
>  
> +               memcpy(skb->data, priv->rx_buf[rx_head], len);
>                 skb_put(skb, len);
>                 skb->protocol = eth_type_trans(skb, ndev);
>                 napi_gro_receive(&priv->napi, skb);

While this seems correct, I wonder why you don't do the normal approach of
dequeuing the skb from the chain and adding a newly allocated skb to it to
save the memcpy.

	Arnd
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html