From: Ben Hutchings <bhutchings@solarflare.com>
To: Jim Baxter <jim_baxter@mentor.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
Frank Li <Frank.Li@freescale.com>,
Fugang Duan <B38611@freescale.com>, <netdev@vger.kernel.org>,
Fabio Estevam <festevam@gmail.com>,
Francois Romieu <romieu@fr.zoreil.com>
Subject: Re: [PATCH net-next v3 1/1] net: fec: Enable imx6 enet checksum acceleration.
Date: Thu, 18 Apr 2013 17:16:36 +0100 [thread overview]
Message-ID: <1366301796.2735.18.camel@bwh-desktop.uk.solarflarecom.com> (raw)
In-Reply-To: <516FEBD3.8000803@mentor.com>
On Thu, 2013-04-18 at 13:49 +0100, Jim Baxter wrote:
> On 17/04/13 22:37, Eric Dumazet wrote:
> > On Wed, 2013-04-17 at 21:07 +0100, Jim Baxter wrote:
> >> Enables hardware generation of IP header and
> >> protocol specific checksums for transmitted
> >> packets.
> >>
> >> Enabled hardware discarding of received packets with
> >> invalid IP header or protocol specific checksums.
> >>
> >> The feature is enabled by default but can be
> >> enabled/disabled by ethtool.
> >>
> >> Signed-off-by: Fugang Duan <B38611@freescale.com>
> >> Signed-off-by: Jim Baxter <jim_baxter@mentor.com>
> >> ---
> >>
> >> +static void
> >> +fec_enet_clear_csum(struct sk_buff *skb, struct net_device *ndev)
> >> +{
> >> + int hdr_len = 0;
> >> +
> >> + /* Only run for packets requiring a checksum. */
> >> + if (skb->ip_summed != CHECKSUM_PARTIAL)
> >> + return;
> >> + if (skb->len < (ETH_HLEN + sizeof(struct iphdr)))
> >> + return;
> >> +
> >
> > You could do the skb_cow_head() here.
>
> I do not know the full length of the header at this point, so I think
> that would be tricky.
>
> >
> >> + if (skb->protocol == htons(ETH_P_IP)) {
> >> + ip_hdr(skb)->check = 0;
But you're already changing it here.
> >> + switch (ip_hdr(skb)->protocol) {
> >> + case IPPROTO_UDP:
> >> + hdr_len = (ETH_HLEN +
> >> + (ip_hdr(skb)->ihl << 2) +
> >> + sizeof(struct udphdr));
> >> + if (skb->len < hdr_len)
> >> + return;
> >> + skb_cow_head(skb, hdr_len);
> >
> > You should not ignore the return value...
> I agree.
> >
> >> + skb_set_transport_header(skb,
> >> + ETH_HLEN + ip_hdrlen(skb));
> >> + udp_hdr(skb)->check = 0;
> >> + break;
> >> + case IPPROTO_TCP:
> >> + hdr_len = (ETH_HLEN +
> >> + (ip_hdr(skb)->ihl << 2) +
> >> + sizeof(struct tcphdr));
> >> + if (skb->len < hdr_len)
> >> + return;
> >> + skb_cow_head(skb, hdr_len);
> >
> > same here
> Do I need to call skb_cow_head here, I am not changing the size of the
> header?
[...]
The length passed to skb_cow_head() may be significant when the skb has
paged fragments. Since you aren't (yet) implementing scatter-gather,
that won't happen. And the headers shouldn't be in paged fragments
anyway. I think you can safely use skb_cow_head(skb, 0).
But you don't actually need to check protocol numbers at all, as the
kernel already specifies where the checksum should be.
So I think this function should look like:
{
if (skb->ip_summed != CHECKSUM_PARTIAL)
return 0;
if (unlikely(skb_cow_head(skb, 0)))
return -1;
*(__sum16 *)(skb->head + skb->csum_start + skb->csum_offset) = 0;
return 0;
}
The caller needs to check for the failure, and free the skb
(kfree_skb()) rather than transmitting it.
Ben.
--
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.
next prev parent reply other threads:[~2013-04-18 16:16 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <Jim Baxter <jim_baxter@mentor.com>
2013-04-17 20:07 ` [PATCH net-next v3 1/1] net: fec: Enable imx6 enet checksum acceleration Jim Baxter
2013-04-17 21:37 ` Eric Dumazet
2013-04-18 12:49 ` Jim Baxter
2013-04-18 16:16 ` Ben Hutchings [this message]
2013-04-18 17:07 ` Ben Hutchings
2013-04-18 17:08 ` Jim Baxter
2013-04-18 17:12 ` Ben Hutchings
2013-04-18 17:21 ` Jim Baxter
2013-04-18 21:27 ` Jim Baxter
2013-04-18 22:03 ` Ben Hutchings
2013-04-17 22:45 ` Francois Romieu
2013-04-18 10:18 ` Jim Baxter
2013-04-18 11:31 ` Fabio Estevam
2013-04-18 21:54 ` Francois Romieu
2013-04-19 8:45 ` Jim Baxter
2013-04-19 15:10 ` [PATCH net-next v4 " Jim Baxter
2013-04-19 15:29 ` Eric Dumazet
2013-04-19 15:55 ` Jim Baxter
2013-04-19 15:56 ` Ben Hutchings
2013-04-19 15:59 ` Eric Dumazet
2013-04-19 15:34 ` Ben Hutchings
2013-04-19 16:16 ` Jim Baxter
2013-04-19 16:20 ` Ben Hutchings
2013-04-19 18:10 ` [PATCH net-next v5 " Jim Baxter
2013-04-19 18:50 ` Ben Hutchings
2013-04-25 7:59 ` David Miller
2013-06-25 23:55 ` [PATCH net-next v1 1/1] net: fec: Add VLAN receive HW support Jim Baxter
2013-06-26 2:22 ` Duan Fugang-B38611
2013-06-26 2:31 ` Duan Fugang-B38611
2013-06-26 2:56 ` Shawn Guo
2013-06-26 3:13 ` Duan Fugang-B38611
2013-06-26 5:49 ` David Miller
2013-06-26 10:09 ` Jim Baxter
2013-06-26 11:18 ` Duan Fugang-B38611
2013-06-26 11:45 ` Jim Baxter
2013-06-27 1:41 ` Duan Fugang-B38611
2013-06-27 9:35 ` Jim Baxter
2013-06-27 9:44 ` Lucas Stach
2013-06-27 14:03 ` Jim Baxter
2013-06-27 18:25 ` [PATCH net v1 1/1] net: fec: Fix Transmitted bytes counter Jim Baxter
2013-06-28 2:11 ` Duan Fugang-B38611
2013-07-01 20:40 ` David Miller
2013-07-02 8:32 ` Jim Baxter
2013-07-02 8:46 ` David Miller
2013-06-28 9:51 ` [PATCH net v2 " Jim Baxter
2013-06-28 10:10 ` Duan Fugang-B38611
2013-06-28 14:08 ` [PATCH net-next v2 1/1] net: fec: Add VLAN receive HW support Jim Baxter
2013-06-29 5:34 ` Duan Fugang-B38611
2013-07-02 0:09 ` David Miller
2013-07-02 9:39 ` Jim Baxter
2013-06-28 15:07 ` [PATCH RFC net-next v1 1/1] net: fec: Fix RMON registers on imx6 Jim Baxter
2013-06-29 5:58 ` Duan Fugang-B38611
[not found] ` <CAFXsbZpgAqvkEy+S83iJNMH9-N7h68MDRuvARE9pmT7HbcpAOQ@mail.gmail.com>
[not found] ` <CAFXsbZoBQ3ODUnFg-VumP+YAfCJ2-d=nL_=Gk2LKXm7PadHUuQ@mail.gmail.com>
2013-07-01 10:16 ` Jim Baxter
2013-07-01 10:31 ` [PATCH " Jim Baxter
[not found] ` <CAFXsbZoDWn4KgAVEpUtajo+PwfnrJoO0eTw9g6+MdQ8b666=EQ@mail.gmail.com>
2013-07-01 13:52 ` Jim Baxter
2013-07-02 19:41 ` David Miller
2013-07-01 13:57 ` [PATCH net-next v3 " Jim Baxter
2013-07-02 21:52 ` [PATCH net-next v3 1/1] net: fec: Add VLAN receive HW support Jim Baxter
2013-07-03 23:45 ` David Miller
2014-05-29 17:12 ` [PATCH v1 0/3] usb: gadget: NCM: Fixes and Multi-frame for TX Jim Baxter
2014-05-29 17:12 ` [PATCH v1 1/3] usb: gadget: NCM: RX function support multiple NDPs Jim Baxter
2014-05-29 18:55 ` Bjørn Mork
2014-05-30 11:45 ` Jim Baxter
2014-05-29 17:12 ` [PATCH v1 2/3] usb: gadget: NCM: Add transmit multi-frame Jim Baxter
2014-05-29 17:12 ` [PATCH v1 3/3] usb: gadget: NCM: Stop RX TCP Bursts getting dropped Jim Baxter
2014-05-29 19:04 ` Eric Dumazet
2014-05-30 11:25 ` Jim Baxter
2014-06-12 9:38 ` Jim Baxter
2014-06-12 9:42 ` David Laight
2014-07-07 17:33 ` [PATCH v2 0/3] usb: gadget: NCM: Fixes and Multi-frame for TX Jim Baxter
2014-07-07 17:33 ` [PATCH v2 1/3] usb: gadget: NCM: RX function support multiple NDPs Jim Baxter
2014-07-07 17:33 ` [PATCH v2 2/3] usb: gadget: NCM: Add transmit multi-frame Jim Baxter
2014-07-07 17:33 ` [PATCH v2 3/3] usb: gadget: NCM: Stop RX TCP Bursts getting dropped Jim Baxter
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