296 lines
7.1 KiB
C
296 lines
7.1 KiB
C
/*
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* IPV4 GSO/GRO offload support
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* Linux INET implementation
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* GRE GSO support
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*/
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#include <linux/skbuff.h>
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#include <linux/init.h>
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#include <net/protocol.h>
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#include <net/gre.h>
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static int gre_gso_send_check(struct sk_buff *skb)
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{
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if (!skb->encapsulation)
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return -EINVAL;
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return 0;
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}
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static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
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netdev_features_t features)
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{
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struct sk_buff *segs = ERR_PTR(-EINVAL);
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netdev_features_t enc_features;
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int ghl;
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struct gre_base_hdr *greh;
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u16 mac_offset = skb->mac_header;
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int mac_len = skb->mac_len;
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__be16 protocol = skb->protocol;
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int tnl_hlen;
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bool csum;
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if (unlikely(skb_shinfo(skb)->gso_type &
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~(SKB_GSO_TCPV4 |
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SKB_GSO_TCPV6 |
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SKB_GSO_UDP |
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SKB_GSO_DODGY |
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SKB_GSO_TCP_ECN |
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SKB_GSO_GRE |
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SKB_GSO_GRE_CSUM |
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SKB_GSO_IPIP)))
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goto out;
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if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
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goto out;
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greh = (struct gre_base_hdr *)skb_transport_header(skb);
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ghl = skb_inner_network_header(skb) - skb_transport_header(skb);
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if (unlikely(ghl < sizeof(*greh)))
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goto out;
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csum = !!(greh->flags & GRE_CSUM);
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if (csum)
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skb->encap_hdr_csum = 1;
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if (unlikely(!pskb_may_pull(skb, ghl)))
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goto out;
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/* setup inner skb. */
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skb->protocol = greh->protocol;
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skb->encapsulation = 0;
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__skb_pull(skb, ghl);
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skb_reset_mac_header(skb);
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skb_set_network_header(skb, skb_inner_network_offset(skb));
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skb->mac_len = skb_inner_network_offset(skb);
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/* segment inner packet. */
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enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
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segs = skb_mac_gso_segment(skb, enc_features);
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if (!segs || IS_ERR(segs)) {
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skb_gso_error_unwind(skb, protocol, ghl, mac_offset, mac_len);
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goto out;
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}
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skb = segs;
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tnl_hlen = skb_tnl_header_len(skb);
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do {
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__skb_push(skb, ghl);
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if (csum) {
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__be32 *pcsum;
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if (skb_has_shared_frag(skb)) {
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int err;
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err = __skb_linearize(skb);
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if (err) {
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kfree_skb_list(segs);
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segs = ERR_PTR(err);
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goto out;
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}
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}
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skb_reset_transport_header(skb);
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greh = (struct gre_base_hdr *)
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skb_transport_header(skb);
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pcsum = (__be32 *)(greh + 1);
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*pcsum = 0;
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*(__sum16 *)pcsum = gso_make_checksum(skb, 0);
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}
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__skb_push(skb, tnl_hlen - ghl);
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skb_reset_inner_headers(skb);
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skb->encapsulation = 1;
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skb_reset_mac_header(skb);
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skb_set_network_header(skb, mac_len);
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skb->mac_len = mac_len;
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skb->protocol = protocol;
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} while ((skb = skb->next));
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out:
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return segs;
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}
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/* Compute the whole skb csum in s/w and store it, then verify GRO csum
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* starting from gro_offset.
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*/
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static __sum16 gro_skb_checksum(struct sk_buff *skb)
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{
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__sum16 sum;
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skb->csum = skb_checksum(skb, 0, skb->len, 0);
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NAPI_GRO_CB(skb)->csum = csum_sub(skb->csum,
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csum_partial(skb->data, skb_gro_offset(skb), 0));
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sum = csum_fold(NAPI_GRO_CB(skb)->csum);
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if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE)) {
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if (unlikely(!sum) && !skb->csum_complete_sw)
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netdev_rx_csum_fault(skb->dev);
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} else {
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skb->ip_summed = CHECKSUM_COMPLETE;
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skb->csum_complete_sw = 1;
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}
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return sum;
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}
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static struct sk_buff **gre_gro_receive(struct sk_buff **head,
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struct sk_buff *skb)
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{
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struct sk_buff **pp = NULL;
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struct sk_buff *p;
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const struct gre_base_hdr *greh;
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unsigned int hlen, grehlen;
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unsigned int off;
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int flush = 1;
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struct packet_offload *ptype;
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__be16 type;
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off = skb_gro_offset(skb);
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hlen = off + sizeof(*greh);
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greh = skb_gro_header_fast(skb, off);
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if (skb_gro_header_hard(skb, hlen)) {
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greh = skb_gro_header_slow(skb, hlen, off);
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if (unlikely(!greh))
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goto out;
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}
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/* Only support version 0 and K (key), C (csum) flags. Note that
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* although the support for the S (seq#) flag can be added easily
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* for GRO, this is problematic for GSO hence can not be enabled
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* here because a GRO pkt may end up in the forwarding path, thus
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* requiring GSO support to break it up correctly.
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*/
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if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
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goto out;
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type = greh->protocol;
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rcu_read_lock();
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ptype = gro_find_receive_by_type(type);
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if (ptype == NULL)
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goto out_unlock;
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grehlen = GRE_HEADER_SECTION;
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if (greh->flags & GRE_KEY)
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grehlen += GRE_HEADER_SECTION;
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if (greh->flags & GRE_CSUM)
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grehlen += GRE_HEADER_SECTION;
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hlen = off + grehlen;
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if (skb_gro_header_hard(skb, hlen)) {
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greh = skb_gro_header_slow(skb, hlen, off);
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if (unlikely(!greh))
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goto out_unlock;
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}
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if (greh->flags & GRE_CSUM) { /* Need to verify GRE csum first */
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__sum16 csum = 0;
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if (skb->ip_summed == CHECKSUM_COMPLETE)
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csum = csum_fold(NAPI_GRO_CB(skb)->csum);
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/* Don't trust csum error calculated/reported by h/w */
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if (skb->ip_summed == CHECKSUM_NONE || csum != 0)
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csum = gro_skb_checksum(skb);
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/* GRE CSUM is the 1's complement of the 1's complement sum
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* of the GRE hdr plus payload so it should add up to 0xffff
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* (and 0 after csum_fold()) just like the IPv4 hdr csum.
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*/
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if (csum)
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goto out_unlock;
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}
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flush = 0;
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for (p = *head; p; p = p->next) {
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const struct gre_base_hdr *greh2;
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if (!NAPI_GRO_CB(p)->same_flow)
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continue;
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/* The following checks are needed to ensure only pkts
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* from the same tunnel are considered for aggregation.
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* The criteria for "the same tunnel" includes:
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* 1) same version (we only support version 0 here)
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* 2) same protocol (we only support ETH_P_IP for now)
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* 3) same set of flags
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* 4) same key if the key field is present.
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*/
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greh2 = (struct gre_base_hdr *)(p->data + off);
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if (greh2->flags != greh->flags ||
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greh2->protocol != greh->protocol) {
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NAPI_GRO_CB(p)->same_flow = 0;
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continue;
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}
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if (greh->flags & GRE_KEY) {
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/* compare keys */
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if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
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NAPI_GRO_CB(p)->same_flow = 0;
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continue;
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}
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}
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}
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skb_gro_pull(skb, grehlen);
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/* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
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skb_gro_postpull_rcsum(skb, greh, grehlen);
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pp = ptype->callbacks.gro_receive(head, skb);
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out_unlock:
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rcu_read_unlock();
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out:
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NAPI_GRO_CB(skb)->flush |= flush;
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return pp;
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}
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static int gre_gro_complete(struct sk_buff *skb, int nhoff)
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{
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struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
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struct packet_offload *ptype;
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unsigned int grehlen = sizeof(*greh);
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int err = -ENOENT;
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__be16 type;
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type = greh->protocol;
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if (greh->flags & GRE_KEY)
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grehlen += GRE_HEADER_SECTION;
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if (greh->flags & GRE_CSUM)
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grehlen += GRE_HEADER_SECTION;
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rcu_read_lock();
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ptype = gro_find_complete_by_type(type);
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if (ptype != NULL)
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err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
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rcu_read_unlock();
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return err;
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}
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static const struct net_offload gre_offload = {
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.callbacks = {
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.gso_send_check = gre_gso_send_check,
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.gso_segment = gre_gso_segment,
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.gro_receive = gre_gro_receive,
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.gro_complete = gre_gro_complete,
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},
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};
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static int __init gre_offload_init(void)
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{
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return inet_add_offload(&gre_offload, IPPROTO_GRE);
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}
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device_initcall(gre_offload_init);
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