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net: gro: move L3 flush checks to tcp_gro_receive and udp_gro_receive_segment
{inet,ipv6}_gro_receive functions perform flush checks (ttl, flags, iph->id, ...) against all packets in a loop. These flush checks are used in all merging UDP and TCP flows. These checks need to be done only once and only against the found p skb, since they only affect flush and not same_flow. This patch leverages correct network header offsets from the cb for both outer and inner network headers - allowing these checks to be done only once, in tcp_gro_receive and udp_gro_receive_segment. As a result, NAPI_GRO_CB(p)->flush is not used at all. In addition, flush_id checks are more declarative and contained in inet_gro_flush, thus removing the need for flush_id in napi_gro_cb. This results in less parsing code for non-loop flush tests for TCP and UDP flows. To make sure results are not within noise range - I've made netfilter drop all TCP packets, and measured CPU performance in GRO (in this case GRO is responsible for about 50% of the CPU utilization). perf top while replaying 64 parallel IP/TCP streams merging in GRO: (gro_receive_network_flush is compiled inline to tcp_gro_receive) net-next: 6.94% [kernel] [k] inet_gro_receive 3.02% [kernel] [k] tcp_gro_receive patch applied: 4.27% [kernel] [k] tcp_gro_receive 4.22% [kernel] [k] inet_gro_receive perf top while replaying 64 parallel IP/IP/TCP streams merging in GRO (same results for any encapsulation, in this case inet_gro_receive is top offender in net-next) net-next: 10.09% [kernel] [k] inet_gro_receive 2.08% [kernel] [k] tcp_gro_receive patch applied: 6.97% [kernel] [k] inet_gro_receive 3.68% [kernel] [k] tcp_gro_receive Signed-off-by: Richard Gobert <richardbgobert@gmail.com> Reviewed-by: Willem de Bruijn <willemb@google.com> Link: https://lore.kernel.org/r/20240509190819.2985-3-richardbgobert@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
parent
186b1ea73a
commit
4b0ebbca3e
6 changed files with 73 additions and 84 deletions
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@ -36,15 +36,15 @@ struct napi_gro_cb {
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/* This is non-zero if the packet cannot be merged with the new skb. */
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/* This is non-zero if the packet cannot be merged with the new skb. */
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u16 flush;
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u16 flush;
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/* Save the IP ID here and check when we get to the transport layer */
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u16 flush_id;
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/* Number of segments aggregated. */
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/* Number of segments aggregated. */
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u16 count;
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u16 count;
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/* Used in ipv6_gro_receive() and foo-over-udp and esp-in-udp */
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/* Used in ipv6_gro_receive() and foo-over-udp and esp-in-udp */
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u16 proto;
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u16 proto;
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/* used to support CHECKSUM_COMPLETE for tunneling protocols */
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__wsum csum;
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/* Used in napi_gro_cb::free */
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/* Used in napi_gro_cb::free */
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#define NAPI_GRO_FREE 1
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#define NAPI_GRO_FREE 1
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#define NAPI_GRO_FREE_STOLEN_HEAD 2
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#define NAPI_GRO_FREE_STOLEN_HEAD 2
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@ -75,8 +75,8 @@ struct napi_gro_cb {
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/* Used in GRE, set in fou/gue_gro_receive */
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/* Used in GRE, set in fou/gue_gro_receive */
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u8 is_fou:1;
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u8 is_fou:1;
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/* Used to determine if flush_id can be ignored */
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/* Used to determine if ipid_offset can be ignored */
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u8 is_atomic:1;
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u8 ip_fixedid:1;
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/* Number of gro_receive callbacks this packet already went through */
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/* Number of gro_receive callbacks this packet already went through */
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u8 recursion_counter:4;
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u8 recursion_counter:4;
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@ -85,9 +85,6 @@ struct napi_gro_cb {
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u8 is_flist:1;
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u8 is_flist:1;
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);
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);
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/* used to support CHECKSUM_COMPLETE for tunneling protocols */
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__wsum csum;
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/* L3 offsets */
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/* L3 offsets */
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union {
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union {
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struct {
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struct {
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@ -442,6 +439,69 @@ static inline __wsum ip6_gro_compute_pseudo(const struct sk_buff *skb,
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skb_gro_len(skb), proto, 0));
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skb_gro_len(skb), proto, 0));
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}
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}
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static inline int inet_gro_flush(const struct iphdr *iph, const struct iphdr *iph2,
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struct sk_buff *p, bool outer)
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{
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const u32 id = ntohl(*(__be32 *)&iph->id);
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const u32 id2 = ntohl(*(__be32 *)&iph2->id);
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const u16 ipid_offset = (id >> 16) - (id2 >> 16);
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const u16 count = NAPI_GRO_CB(p)->count;
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const u32 df = id & IP_DF;
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int flush;
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/* All fields must match except length and checksum. */
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flush = (iph->ttl ^ iph2->ttl) | (iph->tos ^ iph2->tos) | (df ^ (id2 & IP_DF));
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if (flush | (outer && df))
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return flush;
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/* When we receive our second frame we can make a decision on if we
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* continue this flow as an atomic flow with a fixed ID or if we use
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* an incrementing ID.
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*/
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if (count == 1 && df && !ipid_offset)
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NAPI_GRO_CB(p)->ip_fixedid = true;
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return ipid_offset ^ (count * !NAPI_GRO_CB(p)->ip_fixedid);
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}
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static inline int ipv6_gro_flush(const struct ipv6hdr *iph, const struct ipv6hdr *iph2)
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{
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/* <Version:4><Traffic_Class:8><Flow_Label:20> */
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__be32 first_word = *(__be32 *)iph ^ *(__be32 *)iph2;
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/* Flush if Traffic Class fields are different. */
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return !!((first_word & htonl(0x0FF00000)) |
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(__force __be32)(iph->hop_limit ^ iph2->hop_limit));
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}
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static inline int __gro_receive_network_flush(const void *th, const void *th2,
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struct sk_buff *p, const u16 diff,
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bool outer)
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{
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const void *nh = th - diff;
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const void *nh2 = th2 - diff;
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if (((struct iphdr *)nh)->version == 6)
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return ipv6_gro_flush(nh, nh2);
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else
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return inet_gro_flush(nh, nh2, p, outer);
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}
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static inline int gro_receive_network_flush(const void *th, const void *th2,
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struct sk_buff *p)
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{
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const bool encap_mark = NAPI_GRO_CB(p)->encap_mark;
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int off = skb_transport_offset(p);
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int flush;
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flush = __gro_receive_network_flush(th, th2, p, off - NAPI_GRO_CB(p)->network_offset, encap_mark);
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if (encap_mark)
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flush |= __gro_receive_network_flush(th, th2, p, off - NAPI_GRO_CB(p)->inner_network_offset, false);
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return flush;
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}
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int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb);
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int skb_gro_receive(struct sk_buff *p, struct sk_buff *skb);
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int skb_gro_receive_list(struct sk_buff *p, struct sk_buff *skb);
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int skb_gro_receive_list(struct sk_buff *p, struct sk_buff *skb);
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@ -358,8 +358,6 @@ static void gro_list_prepare(const struct list_head *head,
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list_for_each_entry(p, head, list) {
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list_for_each_entry(p, head, list) {
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unsigned long diffs;
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unsigned long diffs;
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NAPI_GRO_CB(p)->flush = 0;
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if (hash != skb_get_hash_raw(p)) {
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if (hash != skb_get_hash_raw(p)) {
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NAPI_GRO_CB(p)->same_flow = 0;
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NAPI_GRO_CB(p)->same_flow = 0;
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continue;
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continue;
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@ -499,7 +497,6 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
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sizeof(u32))); /* Avoid slow unaligned acc */
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sizeof(u32))); /* Avoid slow unaligned acc */
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*(u32 *)&NAPI_GRO_CB(skb)->zeroed = 0;
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*(u32 *)&NAPI_GRO_CB(skb)->zeroed = 0;
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NAPI_GRO_CB(skb)->flush = skb_has_frag_list(skb);
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NAPI_GRO_CB(skb)->flush = skb_has_frag_list(skb);
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NAPI_GRO_CB(skb)->is_atomic = 1;
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NAPI_GRO_CB(skb)->count = 1;
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NAPI_GRO_CB(skb)->count = 1;
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if (unlikely(skb_is_gso(skb))) {
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if (unlikely(skb_is_gso(skb))) {
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NAPI_GRO_CB(skb)->count = skb_shinfo(skb)->gso_segs;
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NAPI_GRO_CB(skb)->count = skb_shinfo(skb)->gso_segs;
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@ -1482,7 +1482,6 @@ struct sk_buff *inet_gro_receive(struct list_head *head, struct sk_buff *skb)
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struct sk_buff *p;
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struct sk_buff *p;
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unsigned int hlen;
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unsigned int hlen;
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unsigned int off;
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unsigned int off;
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unsigned int id;
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int flush = 1;
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int flush = 1;
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int proto;
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int proto;
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@ -1508,13 +1507,10 @@ struct sk_buff *inet_gro_receive(struct list_head *head, struct sk_buff *skb)
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goto out;
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goto out;
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NAPI_GRO_CB(skb)->proto = proto;
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NAPI_GRO_CB(skb)->proto = proto;
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id = ntohl(*(__be32 *)&iph->id);
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flush = (u16)((ntohl(*(__be32 *)iph) ^ skb_gro_len(skb)) | (ntohl(*(__be32 *)&iph->id) & ~IP_DF));
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flush = (u16)((ntohl(*(__be32 *)iph) ^ skb_gro_len(skb)) | (id & ~IP_DF));
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id >>= 16;
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list_for_each_entry(p, head, list) {
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list_for_each_entry(p, head, list) {
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struct iphdr *iph2;
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struct iphdr *iph2;
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u16 flush_id;
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if (!NAPI_GRO_CB(p)->same_flow)
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if (!NAPI_GRO_CB(p)->same_flow)
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continue;
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continue;
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@ -1531,43 +1527,8 @@ struct sk_buff *inet_gro_receive(struct list_head *head, struct sk_buff *skb)
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NAPI_GRO_CB(p)->same_flow = 0;
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NAPI_GRO_CB(p)->same_flow = 0;
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continue;
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continue;
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}
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}
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/* All fields must match except length and checksum. */
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NAPI_GRO_CB(p)->flush |=
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(iph->ttl ^ iph2->ttl) |
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(iph->tos ^ iph2->tos) |
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((iph->frag_off ^ iph2->frag_off) & htons(IP_DF));
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NAPI_GRO_CB(p)->flush |= flush;
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/* We need to store of the IP ID check to be included later
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* when we can verify that this packet does in fact belong
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* to a given flow.
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*/
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flush_id = (u16)(id - ntohs(iph2->id));
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/* This bit of code makes it much easier for us to identify
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* the cases where we are doing atomic vs non-atomic IP ID
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* checks. Specifically an atomic check can return IP ID
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* values 0 - 0xFFFF, while a non-atomic check can only
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* return 0 or 0xFFFF.
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*/
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if (!NAPI_GRO_CB(p)->is_atomic ||
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!(iph->frag_off & htons(IP_DF))) {
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flush_id ^= NAPI_GRO_CB(p)->count;
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flush_id = flush_id ? 0xFFFF : 0;
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}
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/* If the previous IP ID value was based on an atomic
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* datagram we can overwrite the value and ignore it.
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*/
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if (NAPI_GRO_CB(skb)->is_atomic)
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NAPI_GRO_CB(p)->flush_id = flush_id;
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else
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NAPI_GRO_CB(p)->flush_id |= flush_id;
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}
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}
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NAPI_GRO_CB(skb)->is_atomic = !!(iph->frag_off & htons(IP_DF));
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NAPI_GRO_CB(skb)->flush |= flush;
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NAPI_GRO_CB(skb)->flush |= flush;
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NAPI_GRO_CB(skb)->inner_network_offset = off;
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NAPI_GRO_CB(skb)->inner_network_offset = off;
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@ -313,10 +313,8 @@ struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb,
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if (!p)
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if (!p)
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goto out_check_final;
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goto out_check_final;
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/* Include the IP ID check below from the inner most IP hdr */
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th2 = tcp_hdr(p);
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th2 = tcp_hdr(p);
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flush = NAPI_GRO_CB(p)->flush;
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flush = (__force int)(flags & TCP_FLAG_CWR);
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flush |= (__force int)(flags & TCP_FLAG_CWR);
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flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
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flush |= (__force int)((flags ^ tcp_flag_word(th2)) &
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~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
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~(TCP_FLAG_CWR | TCP_FLAG_FIN | TCP_FLAG_PSH));
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flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
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flush |= (__force int)(th->ack_seq ^ th2->ack_seq);
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@ -324,16 +322,7 @@ struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb,
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flush |= *(u32 *)((u8 *)th + i) ^
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flush |= *(u32 *)((u8 *)th + i) ^
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*(u32 *)((u8 *)th2 + i);
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*(u32 *)((u8 *)th2 + i);
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/* When we receive our second frame we can made a decision on if we
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flush |= gro_receive_network_flush(th, th2, p);
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* continue this flow as an atomic flow with a fixed ID or if we use
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* an incrementing ID.
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*/
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if (NAPI_GRO_CB(p)->flush_id != 1 ||
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NAPI_GRO_CB(p)->count != 1 ||
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!NAPI_GRO_CB(p)->is_atomic)
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flush |= NAPI_GRO_CB(p)->flush_id;
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else
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NAPI_GRO_CB(p)->is_atomic = false;
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mss = skb_shinfo(p)->gso_size;
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mss = skb_shinfo(p)->gso_size;
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iph->daddr, 0);
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iph->daddr, 0);
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skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4 |
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skb_shinfo(skb)->gso_type |= SKB_GSO_TCPV4 |
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(NAPI_GRO_CB(skb)->is_atomic * SKB_GSO_TCP_FIXEDID);
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(NAPI_GRO_CB(skb)->ip_fixedid * SKB_GSO_TCP_FIXEDID);
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tcp_gro_complete(skb);
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tcp_gro_complete(skb);
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return 0;
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return 0;
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return p;
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return p;
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}
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}
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flush = NAPI_GRO_CB(p)->flush;
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flush = gro_receive_network_flush(uh, uh2, p);
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if (NAPI_GRO_CB(p)->flush_id != 1 ||
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NAPI_GRO_CB(p)->count != 1 ||
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!NAPI_GRO_CB(p)->is_atomic)
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flush |= NAPI_GRO_CB(p)->flush_id;
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else
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NAPI_GRO_CB(p)->is_atomic = false;
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/* Terminate the flow on len mismatch or if it grow "too much".
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/* Terminate the flow on len mismatch or if it grow "too much".
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* Under small packet flood GRO count could elsewhere grow a lot
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* Under small packet flood GRO count could elsewhere grow a lot
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@ -290,19 +290,8 @@ INDIRECT_CALLABLE_SCOPE struct sk_buff *ipv6_gro_receive(struct list_head *head,
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nlen - sizeof(struct ipv6hdr)))
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nlen - sizeof(struct ipv6hdr)))
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goto not_same_flow;
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goto not_same_flow;
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}
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}
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/* flush if Traffic Class fields are different */
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NAPI_GRO_CB(p)->flush |= !!((first_word & htonl(0x0FF00000)) |
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(__force __be32)(iph->hop_limit ^ iph2->hop_limit));
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NAPI_GRO_CB(p)->flush |= flush;
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/* If the previous IP ID value was based on an atomic
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* datagram we can overwrite the value and ignore it.
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*/
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if (NAPI_GRO_CB(skb)->is_atomic)
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NAPI_GRO_CB(p)->flush_id = 0;
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}
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}
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NAPI_GRO_CB(skb)->is_atomic = true;
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NAPI_GRO_CB(skb)->flush |= flush;
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NAPI_GRO_CB(skb)->flush |= flush;
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skb_gro_postpull_rcsum(skb, iph, nlen);
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skb_gro_postpull_rcsum(skb, iph, nlen);
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