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Date: Thu, 10 Jan 2013 11:47:24 -0800
From: Eric Dumazet <eric.dumazet@...il.com>
To: Pravin B Shelar <pshelar@...ira.com>
Cc: dev@...nvswitch.org, netdev@...r.kernel.org, jesse@...ira.com
Subject: Re: [PATCH 1/5] GRE: Add segmentation offload for GRE TAP device.
On Mon, 2013-01-07 at 18:31 -0800, Pravin B Shelar wrote:
> From: Pravin Shelar <pshelar@...ira.com>
Do you have some perf numbers to share ?
> Signed-off-by: Pravin B Shelar <pshelar@...ira.com>
> ---
> include/linux/skbuff.h | 12 ++++++
> include/net/gre.h | 6 +++
> net/ipv4/af_inet.c | 1 +
> net/ipv4/gre.c | 101 ++++++++++++++++++++++++++++++++++++++++++++++++
> net/ipv4/tcp.c | 1 +
> net/ipv4/udp.c | 3 +-
> net/ipv6/ip6_offload.c | 1 +
> net/ipv6/udp_offload.c | 3 +-
> 8 files changed, 126 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 320e976..43033f0 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -307,6 +307,8 @@ enum {
> SKB_GSO_TCPV6 = 1 << 4,
>
> SKB_GSO_FCOE = 1 << 5,
> +
> + SKB_GSO_GRE = 1 << 6,
> };
>
> #if BITS_PER_LONG > 32
> @@ -797,6 +799,16 @@ static inline int skb_cloned(const struct sk_buff *skb)
> (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1;
> }
>
> +static inline int skb_unclone(struct sk_buff *skb, gfp_t pri)
> +{
> + might_sleep_if(pri & __GFP_WAIT);
> +
> + if (skb_cloned(skb))
> + return pskb_expand_head(skb, 0, 0, pri);
> +
> + return 0;
> +}
Should be a commit on its own, and use a "bool"
We have some places in network stack that could use this helper.
(net/ipv6/ah6.c, net/ipv6/reassembly.c,
net/ipv6/xfrm6_mode_tunnel.c, ...)
> +
> /**
> * skb_header_cloned - is the header a clone
> * @skb: buffer to check
> diff --git a/include/net/gre.h b/include/net/gre.h
> index 8266547..f7d5bfb 100644
> --- a/include/net/gre.h
> +++ b/include/net/gre.h
> @@ -15,4 +15,10 @@ struct gre_protocol {
> int gre_add_protocol(const struct gre_protocol *proto, u8 version);
> int gre_del_protocol(const struct gre_protocol *proto, u8 version);
>
> +struct gre_base_hdr {
> + __be16 flags;
> + __be16 protocol;
> +};
> +#define GRE_HEADER_SECTION 4
> +
> #endif
> diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
> index 24b384b..9a3d5d2 100644
> --- a/net/ipv4/af_inet.c
> +++ b/net/ipv4/af_inet.c
> @@ -1306,6 +1306,7 @@ static struct sk_buff *inet_gso_segment(struct sk_buff *skb,
> SKB_GSO_UDP |
> SKB_GSO_DODGY |
> SKB_GSO_TCP_ECN |
> + SKB_GSO_GRE |
> 0)))
> goto out;
>
> diff --git a/net/ipv4/gre.c b/net/ipv4/gre.c
> index 42a4910..0eaaf44 100644
> --- a/net/ipv4/gre.c
> +++ b/net/ipv4/gre.c
> @@ -19,6 +19,7 @@
> #include <linux/in.h>
> #include <linux/ip.h>
> #include <linux/netdevice.h>
> +#include <linux/if_tunnel.h>
> #include <linux/spinlock.h>
> #include <net/protocol.h>
> #include <net/gre.h>
> @@ -112,12 +113,105 @@ static void gre_err(struct sk_buff *skb, u32 info)
> rcu_read_unlock();
> }
>
> +static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
> + netdev_features_t features)
> +{
> + struct sk_buff *segs = ERR_PTR(-EINVAL);
> + struct gre_base_hdr *greh;
> + unsigned char *mac = skb_mac_header(skb);
You should not init mac here, but after the pskb_may_pull()
> + int net_hlen = skb_network_header_len(skb);
> + int ghl = GRE_HEADER_SECTION;
> + int mac_len;
> + int doffset;
> +
> + if (unlikely(skb_shinfo(skb)->gso_type &
> + ~(SKB_GSO_TCPV4 |
> + SKB_GSO_UDP |
> + SKB_GSO_DODGY |
> + SKB_GSO_TCP_ECN |
> + SKB_GSO_GRE |
> + 0)))
> + goto out;
> +
> + if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
> + goto out;
> +
> + greh = (struct gre_base_hdr *)skb_transport_header(skb);
> +
> + if (greh->flags & GRE_KEY)
> + ghl += GRE_HEADER_SECTION;
> + if (greh->flags & GRE_CSUM)
> + ghl += GRE_HEADER_SECTION;
> +
> + if (unlikely(!pskb_may_pull(skb, ghl)))
> + goto out;
> +
mac can now point to freed memory. You should move its init here :
mac = skb_mac_header(skb);
same for greh
greh = (struct gre_base_hdr *)skb_transport_header(skb);
> + __skb_pull(skb, ghl);
> + skb_reset_mac_header(skb);
> + skb_set_network_header(skb, skb->mac_len);
> + doffset = skb_mac_header(skb) - mac;
> + /* segment inner packet. */
> + segs = skb_gso_segment(skb, 0);
> + if (!segs || IS_ERR(segs))
> + goto out;
> +
> + mac_len = skb_inner_network_header(skb) - ((unsigned char *)greh + ghl);
> + skb = segs;
> + do {
> + unsigned char *smac;
> +
> + skb_push(skb, doffset);
> +
> + skb_reset_mac_header(skb);
> + skb_set_network_header(skb, mac_len);
> + skb_set_transport_header(skb,
> + skb_network_offset(skb) + net_hlen);
> + smac = skb_mac_header(skb);
> + skb->mac_len = mac_len;
> + /* Copy entire outer header from original skb. */
> + memcpy(smac, mac, doffset);
> +
> + greh = (struct gre_base_hdr *)skb_transport_header(skb);
> + if (greh->flags & GRE_CSUM) {
> + __be32 *gre_csum = (__be32 *)(greh + 1);
> + *gre_csum = 0;
> + *(__sum16 *)gre_csum = csum_fold(skb_checksum(skb,
> + skb_transport_offset(skb),
> + skb->len - skb_transport_offset(skb),
> + 0));
> + }
> + } while ((skb = skb->next));
> +
> +out:
> + return segs;
> +}
> +
--
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