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Date: Tue, 31 Dec 2013 14:10:09 -0500
From: Boris Ostrovsky <boris.ostrovsky@...cle.com>
To: Paul Durrant <paul.durrant@...rix.com>
CC: xen-devel@...ts.xen.org, netdev@...r.kernel.org,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
David Vrabel <david.vrabel@...rix.com>,
Ian Campbell <ian.campbell@...rix.com>,
Wei Liu <wei.liu2@...rix.com>, Annie Li <annie.li@...cle.com>
Subject: Re: [PATCH net-next v3] xen-netfront: Add support for IPv6 offloads
On 11/26/2013 11:41 AM, Paul Durrant wrote:
> This patch adds support for IPv6 checksum offload and GSO when those
> features are available in the backend.
Sorry for late review. Mostly style comments.
>
> Signed-off-by: Paul Durrant <paul.durrant@...rix.com>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> Cc: Boris Ostrovsky <boris.ostrovsky@...cle.com>
> Cc: David Vrabel <david.vrabel@...rix.com>
> Cc: Ian Campbell <ian.campbell@...rix.com>
> Cc: Wei Liu <wei.liu2@...rix.com>
> Cc: Annie Li <annie.li@...cle.com>
> ---
>
> v3:
> - Addressed comments raised by Annie Li
>
> v2:
> - Addressed comments raised by Ian Campbell
>
> drivers/net/xen-netfront.c | 239 ++++++++++++++++++++++++++++++++++++++++----
> include/linux/ipv6.h | 2 +
> 2 files changed, 224 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
> index dd1011e..fe747e4 100644
> --- a/drivers/net/xen-netfront.c
> +++ b/drivers/net/xen-netfront.c
> @@ -616,7 +616,9 @@ static int xennet_start_xmit(struct sk_buff *skb, struct net_device *dev)
> tx->flags |= XEN_NETTXF_extra_info;
>
> gso->u.gso.size = skb_shinfo(skb)->gso_size;
> - gso->u.gso.type = XEN_NETIF_GSO_TYPE_TCPV4;
> + gso->u.gso.type = (skb_shinfo(skb)->gso_type & SKB_GSO_TCPV6) ?
> + XEN_NETIF_GSO_TYPE_TCPV6 :
> + XEN_NETIF_GSO_TYPE_TCPV4;
> gso->u.gso.pad = 0;
> gso->u.gso.features = 0;
>
> @@ -808,15 +810,18 @@ static int xennet_set_skb_gso(struct sk_buff *skb,
> return -EINVAL;
> }
>
> - /* Currently only TCPv4 S.O. is supported. */
> - if (gso->u.gso.type != XEN_NETIF_GSO_TYPE_TCPV4) {
> + if (gso->u.gso.type != XEN_NETIF_GSO_TYPE_TCPV4 &&
> + gso->u.gso.type != XEN_NETIF_GSO_TYPE_TCPV6) {
> if (net_ratelimit())
> pr_warn("Bad GSO type %d\n", gso->u.gso.type);
> return -EINVAL;
> }
>
> skb_shinfo(skb)->gso_size = gso->u.gso.size;
> - skb_shinfo(skb)->gso_type = SKB_GSO_TCPV4;
> + skb_shinfo(skb)->gso_type =
> + (gso->u.gso.type == XEN_NETIF_GSO_TYPE_TCPV4) ?
> + SKB_GSO_TCPV4 :
> + SKB_GSO_TCPV6;
>
> /* Header must be checked, and gso_segs computed. */
> skb_shinfo(skb)->gso_type |= SKB_GSO_DODGY;
> @@ -856,11 +861,42 @@ static RING_IDX xennet_fill_frags(struct netfront_info *np,
> return cons;
> }
>
> -static int checksum_setup(struct net_device *dev, struct sk_buff *skb)
> +static inline bool maybe_pull_tail(struct sk_buff *skb, unsigned int min,
> + unsigned int max)
Should this routine return error code instead of a boolean? Otherwise
it's not clear what "false" should mean --- whether it is that it failed
to pull or that the pull wasn't needed.
> {
> - struct iphdr *iph;
> - int err = -EPROTO;
> + int target;
> +
> + BUG_ON(max < min);
> +
> + if (!skb_is_nonlinear(skb) || skb_headlen(skb) >= min)
> + return true;
> +
> + /* If we need to pullup then pullup to max, so we hopefully
> + * won't need to do it again.
> + */
Comment style.
> + target = min_t(int, skb->len, max);
> + __pskb_pull_tail(skb, target - skb_headlen(skb));
> +
> + if (skb_headlen(skb) < min) {
Why not explicitly check whether__pskb_pull_tail() returned NULL ?
> + net_err_ratelimited("Failed to pullup packet header\n");
> + return false;
> + }
> +
> + return true;
> +}
> +
> +/* This value should be large enough to cover a tagged ethernet header plus
> + * maximally sized IP and TCP or UDP headers.
> + */
Comment style.
> +#define MAX_IP_HEADER 128
> +
> +static int checksum_setup_ip(struct net_device *dev, struct sk_buff *skb)
> +{
> + struct iphdr *iph = (void *)skb->data;
> + unsigned int header_size;
> + unsigned int off;
> int recalculate_partial_csum = 0;
> + int err = -EPROTO;
>
> /*
> * A GSO SKB must be CHECKSUM_PARTIAL. However some buggy
> @@ -879,40 +915,158 @@ static int checksum_setup(struct net_device *dev, struct sk_buff *skb)
> if (skb->ip_summed != CHECKSUM_PARTIAL)
> return 0;
>
> - if (skb->protocol != htons(ETH_P_IP))
> + off = sizeof(struct iphdr);
> +
> + header_size = skb->network_header + off;
> + if (!maybe_pull_tail(skb, header_size, MAX_IP_HEADER))
> goto out;
>
> - iph = (void *)skb->data;
> + off = iph->ihl * 4;
>
> switch (iph->protocol) {
> case IPPROTO_TCP:
> - if (!skb_partial_csum_set(skb, 4 * iph->ihl,
> + if (!skb_partial_csum_set(skb, off,
> offsetof(struct tcphdr, check)))
> goto out;
>
> if (recalculate_partial_csum) {
> struct tcphdr *tcph = tcp_hdr(skb);
> +
> + header_size = skb->network_header +
> + off +
> + sizeof(struct tcphdr);
You can put these (off and sizeof) onto the same line.
> + if (!maybe_pull_tail(skb, header_size, MAX_IP_HEADER))
> + goto out;
> +
> tcph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
> - skb->len - iph->ihl*4,
> + skb->len - off,
> IPPROTO_TCP, 0);
> }
> break;
> case IPPROTO_UDP:
> - if (!skb_partial_csum_set(skb, 4 * iph->ihl,
> + if (!skb_partial_csum_set(skb, off,
> offsetof(struct udphdr, check)))
> goto out;
>
> if (recalculate_partial_csum) {
> struct udphdr *udph = udp_hdr(skb);
> +
> + header_size = skb->network_header +
> + off +
> + sizeof(struct udphdr);
> + if (!maybe_pull_tail(skb, header_size, MAX_IP_HEADER))
> + goto out;
> +
> udph->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr,
> - skb->len - iph->ihl*4,
> + skb->len - off,
> IPPROTO_UDP, 0);
> }
> break;
> default:
> - if (net_ratelimit())
> - pr_err("Attempting to checksum a non-TCP/UDP packet, dropping a protocol %d packet\n",
> - iph->protocol);
> + net_err_ratelimited("Attempting to checksum a non-TCP/UDP packet, dropping a protocol %d packet\n",
> + iph->protocol);
> + goto out;
> + }
> +
> + err = 0;
> +
> +out:
> + return err;
> +}
> +
> +/* This value should be large enough to cover a tagged ethernet header plus
> + * an IPv6 header, all options, and a maximal TCP or UDP header.
> + */
> +#define MAX_IPV6_HEADER 256
> +
> +static int checksum_setup_ipv6(struct net_device *dev, struct sk_buff *skb)
> +{
> + struct ipv6hdr *ipv6h = (void *)skb->data;
> + u8 nexthdr;
> + unsigned int header_size;
> + unsigned int off;
> + bool fragment;
> + bool done;
> + int err = -EPROTO;
> +
> + done = false;
This should probably be moved down to the beginning of the while loop.
And you also need to initialize fragment to "false" (and possibly rename
it to is_fragment?)
> +
> + /* A non-CHECKSUM_PARTIAL SKB does not require setup. */
> + if (skb->ip_summed != CHECKSUM_PARTIAL)
> + return 0;
> +
> + off = sizeof(struct ipv6hdr);
> +
> + header_size = skb->network_header + off;
> + if (!maybe_pull_tail(skb, header_size, MAX_IPV6_HEADER))
> + goto out;
> +
> + nexthdr = ipv6h->nexthdr;
> +
> + while ((off <= sizeof(struct ipv6hdr) + ntohs(ipv6h->payload_len)) &&
> + !done) {
> + switch (nexthdr) {
> + case IPPROTO_DSTOPTS:
> + case IPPROTO_HOPOPTS:
> + case IPPROTO_ROUTING: {
> + struct ipv6_opt_hdr *hp = (void *)(skb->data + off);
> +
> + header_size = skb->network_header +
> + off +
> + sizeof(struct ipv6_opt_hdr);
I'd merge the last two lines.
> + if (!maybe_pull_tail(skb, header_size, MAX_IPV6_HEADER))
> + goto out;
> +
> + nexthdr = hp->nexthdr;
> + off += ipv6_optlen(hp);
> + break;
> + }
> + case IPPROTO_AH: {
> + struct ip_auth_hdr *hp = (void *)(skb->data + off);
> +
> + header_size = skb->network_header +
> + off +
> + sizeof(struct ip_auth_hdr);
Here as well.
> + if (!maybe_pull_tail(skb, header_size, MAX_IPV6_HEADER))
> + goto out;
> +
> + nexthdr = hp->nexthdr;
> + off += ipv6_ahlen(hp);
> + break;
> + }
> + case IPPROTO_FRAGMENT:
> + fragment = true;
> + /* fall through */
> + default:
> + done = true;
> + break;
> + }
> + }
> +
> + if (!done) {
> + net_err_ratelimited("Failed to parse packet header\n");
> + goto out;
> + }
> +
> + if (fragment) {
> + net_err_ratelimited("Packet is a fragment!\n");
> + goto out;
> + }
> +
> + switch (nexthdr) {
> + case IPPROTO_TCP:
> + if (!skb_partial_csum_set(skb, off,
> + offsetof(struct tcphdr, check)))
> + goto out;
> + break;
> + case IPPROTO_UDP:
> + if (!skb_partial_csum_set(skb, off,
> + offsetof(struct udphdr, check)))
> + goto out;
> + break;
> + default:
> + net_err_ratelimited("Attempting to checksum a non-TCP/UDP packet, dropping a protocol %d packet\n",
> + nexthdr);
> goto out;
> }
>
> @@ -922,6 +1076,25 @@ out:
> return err;
> }
>
> +static int checksum_setup(struct net_device *dev, struct sk_buff *skb)
> +{
> + int err;
Initialize to -EPROTO (just to keep consistent with the rest of the file)
> +
> + switch (skb->protocol) {
> + case htons(ETH_P_IP):
> + err = checksum_setup_ip(dev, skb);
> + break;
> + case htons(ETH_P_IPV6):
> + err = checksum_setup_ipv6(dev, skb);
> + break;
> + default:
> + err = -EPROTO;
> + break;
> + }
> +
> + return err;
> +}
> +
> static int handle_incoming_queue(struct net_device *dev,
> struct sk_buff_head *rxq)
> {
> @@ -1232,6 +1405,15 @@ static netdev_features_t xennet_fix_features(struct net_device *dev,
> features &= ~NETIF_F_SG;
> }
>
> + if (features & NETIF_F_IPV6_CSUM) {
> + if (xenbus_scanf(XBT_NIL, np->xbdev->otherend,
> + "feature-ipv6-csum-offload", "%d", &val) < 0)
> + val = 0;
> +
> + if (!val)
> + features &= ~NETIF_F_IPV6_CSUM;
> + }
> +
> if (features & NETIF_F_TSO) {
> if (xenbus_scanf(XBT_NIL, np->xbdev->otherend,
> "feature-gso-tcpv4", "%d", &val) < 0)
> @@ -1241,6 +1423,15 @@ static netdev_features_t xennet_fix_features(struct net_device *dev,
> features &= ~NETIF_F_TSO;
> }
>
> + if (features & NETIF_F_TSO6) {
> + if (xenbus_scanf(XBT_NIL, np->xbdev->otherend,
> + "feature-gso-tcpv6", "%d", &val) < 0)
> + val = 0;
> +
> + if (!val)
> + features &= ~NETIF_F_TSO6;
> + }
> +
> return features;
> }
>
> @@ -1373,7 +1564,9 @@ static struct net_device *xennet_create_dev(struct xenbus_device *dev)
> netif_napi_add(netdev, &np->napi, xennet_poll, 64);
> netdev->features = NETIF_F_IP_CSUM | NETIF_F_RXCSUM |
> NETIF_F_GSO_ROBUST;
> - netdev->hw_features = NETIF_F_IP_CSUM | NETIF_F_SG | NETIF_F_TSO;
> + netdev->hw_features = NETIF_F_SG |
> + NETIF_F_IPV6_CSUM |
> + NETIF_F_TSO | NETIF_F_TSO6;
Can you merge these three lines and stay under 80? If not, merge either
of the two of them.
-boris
>
> /*
> * Assume that all hw features are available for now. This set
> @@ -1751,6 +1944,18 @@ again:
> goto abort_transaction;
> }
>
> + err = xenbus_printf(xbt, dev->nodename, "feature-gso-tcpv6", "%d", 1);
> + if (err) {
> + message = "writing feature-gso-tcpv6";
> + goto abort_transaction;
> + }
> +
> + err = xenbus_printf(xbt, dev->nodename, "feature-ipv6-csum-offload", "%d", 1);
> + if (err) {
> + message = "writing feature-ipv6-csum-offload";
> + goto abort_transaction;
> + }
> +
> err = xenbus_transaction_end(xbt, 0);
> if (err) {
> if (err == -EAGAIN)
> diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
> index 5d89d1b..10f1b03 100644
> --- a/include/linux/ipv6.h
> +++ b/include/linux/ipv6.h
> @@ -4,6 +4,8 @@
> #include <uapi/linux/ipv6.h>
>
> #define ipv6_optlen(p) (((p)->hdrlen+1) << 3)
> +#define ipv6_ahlen(p) (((p)->hdrlen+2) << 2);
> +
> /*
> * This structure contains configuration options per IPv6 link.
> */
--
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