c9d1d23e52
When forwarding TCP after GRO, software segmentation is very expensive, especially when the checksum needs to be recalculated. One case where that's currently unavoidable is when routing packets over PPPoE. Performance improves significantly when using fraglist GRO implemented in the same way as for UDP. When NETIF_F_GRO_FRAGLIST is enabled, perform a lookup for an established socket in the same netns as the receiving device. While this may not cover all relevant use cases in multi-netns configurations, it should be good enough for most configurations that need this. Here's a measurement of running 2 TCP streams through a MediaTek MT7622 device (2-core Cortex-A53), which runs NAT with flow offload enabled from one ethernet port to PPPoE on another ethernet port + cake qdisc set to 1Gbps. rx-gro-list off: 630 Mbit/s, CPU 35% idle rx-gro-list on: 770 Mbit/s, CPU 40% idle Acked-by: Paolo Abeni <pabeni@redhat.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Felix Fietkau <nbd@nbd.name> Reviewed-by: David Ahern <dsahern@kernel.org> Reviewed-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com>
499 lines
12 KiB
C
499 lines
12 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* IPV4 GSO/GRO offload support
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* Linux INET implementation
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*
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* TCPv4 GSO/GRO support
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*/
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#include <linux/indirect_call_wrapper.h>
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#include <linux/skbuff.h>
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#include <net/gro.h>
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#include <net/gso.h>
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#include <net/tcp.h>
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#include <net/protocol.h>
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static void tcp_gso_tstamp(struct sk_buff *skb, unsigned int ts_seq,
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unsigned int seq, unsigned int mss)
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{
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while (skb) {
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if (before(ts_seq, seq + mss)) {
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skb_shinfo(skb)->tx_flags |= SKBTX_SW_TSTAMP;
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skb_shinfo(skb)->tskey = ts_seq;
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return;
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}
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skb = skb->next;
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seq += mss;
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}
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}
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static void __tcpv4_gso_segment_csum(struct sk_buff *seg,
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__be32 *oldip, __be32 newip,
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__be16 *oldport, __be16 newport)
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{
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struct tcphdr *th;
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struct iphdr *iph;
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if (*oldip == newip && *oldport == newport)
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return;
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th = tcp_hdr(seg);
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iph = ip_hdr(seg);
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inet_proto_csum_replace4(&th->check, seg, *oldip, newip, true);
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inet_proto_csum_replace2(&th->check, seg, *oldport, newport, false);
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*oldport = newport;
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csum_replace4(&iph->check, *oldip, newip);
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*oldip = newip;
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}
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static struct sk_buff *__tcpv4_gso_segment_list_csum(struct sk_buff *segs)
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{
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const struct tcphdr *th;
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const struct iphdr *iph;
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struct sk_buff *seg;
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struct tcphdr *th2;
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struct iphdr *iph2;
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seg = segs;
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th = tcp_hdr(seg);
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iph = ip_hdr(seg);
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th2 = tcp_hdr(seg->next);
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iph2 = ip_hdr(seg->next);
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if (!(*(const u32 *)&th->source ^ *(const u32 *)&th2->source) &&
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iph->daddr == iph2->daddr && iph->saddr == iph2->saddr)
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return segs;
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while ((seg = seg->next)) {
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th2 = tcp_hdr(seg);
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iph2 = ip_hdr(seg);
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__tcpv4_gso_segment_csum(seg,
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&iph2->saddr, iph->saddr,
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&th2->source, th->source);
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__tcpv4_gso_segment_csum(seg,
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&iph2->daddr, iph->daddr,
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&th2->dest, th->dest);
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}
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return segs;
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}
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static struct sk_buff *__tcp4_gso_segment_list(struct sk_buff *skb,
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netdev_features_t features)
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{
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skb = skb_segment_list(skb, features, skb_mac_header_len(skb));
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if (IS_ERR(skb))
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return skb;
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return __tcpv4_gso_segment_list_csum(skb);
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}
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static struct sk_buff *tcp4_gso_segment(struct sk_buff *skb,
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netdev_features_t features)
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{
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if (!(skb_shinfo(skb)->gso_type & SKB_GSO_TCPV4))
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return ERR_PTR(-EINVAL);
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if (!pskb_may_pull(skb, sizeof(struct tcphdr)))
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return ERR_PTR(-EINVAL);
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if (skb_shinfo(skb)->gso_type & SKB_GSO_FRAGLIST)
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return __tcp4_gso_segment_list(skb, features);
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if (unlikely(skb->ip_summed != CHECKSUM_PARTIAL)) {
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const struct iphdr *iph = ip_hdr(skb);
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struct tcphdr *th = tcp_hdr(skb);
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/* Set up checksum pseudo header, usually expect stack to
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* have done this already.
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*/
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th->check = 0;
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skb->ip_summed = CHECKSUM_PARTIAL;
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__tcp_v4_send_check(skb, iph->saddr, iph->daddr);
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}
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return tcp_gso_segment(skb, features);
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}
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struct sk_buff *tcp_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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unsigned int sum_truesize = 0;
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struct tcphdr *th;
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unsigned int thlen;
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unsigned int seq;
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unsigned int oldlen;
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unsigned int mss;
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struct sk_buff *gso_skb = skb;
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__sum16 newcheck;
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bool ooo_okay, copy_destructor;
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__wsum delta;
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th = tcp_hdr(skb);
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thlen = th->doff * 4;
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if (thlen < sizeof(*th))
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goto out;
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if (!pskb_may_pull(skb, thlen))
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goto out;
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oldlen = ~skb->len;
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__skb_pull(skb, thlen);
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mss = skb_shinfo(skb)->gso_size;
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if (unlikely(skb->len <= mss))
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goto out;
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if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
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/* Packet is from an untrusted source, reset gso_segs. */
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skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
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segs = NULL;
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goto out;
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}
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copy_destructor = gso_skb->destructor == tcp_wfree;
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ooo_okay = gso_skb->ooo_okay;
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/* All segments but the first should have ooo_okay cleared */
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skb->ooo_okay = 0;
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segs = skb_segment(skb, features);
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if (IS_ERR(segs))
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goto out;
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/* Only first segment might have ooo_okay set */
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segs->ooo_okay = ooo_okay;
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/* GSO partial and frag_list segmentation only requires splitting
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* the frame into an MSS multiple and possibly a remainder, both
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* cases return a GSO skb. So update the mss now.
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*/
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if (skb_is_gso(segs))
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mss *= skb_shinfo(segs)->gso_segs;
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delta = (__force __wsum)htonl(oldlen + thlen + mss);
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skb = segs;
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th = tcp_hdr(skb);
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seq = ntohl(th->seq);
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if (unlikely(skb_shinfo(gso_skb)->tx_flags & SKBTX_SW_TSTAMP))
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tcp_gso_tstamp(segs, skb_shinfo(gso_skb)->tskey, seq, mss);
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newcheck = ~csum_fold(csum_add(csum_unfold(th->check), delta));
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while (skb->next) {
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th->fin = th->psh = 0;
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th->check = newcheck;
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if (skb->ip_summed == CHECKSUM_PARTIAL)
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gso_reset_checksum(skb, ~th->check);
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else
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th->check = gso_make_checksum(skb, ~th->check);
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seq += mss;
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if (copy_destructor) {
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skb->destructor = gso_skb->destructor;
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skb->sk = gso_skb->sk;
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sum_truesize += skb->truesize;
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}
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skb = skb->next;
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th = tcp_hdr(skb);
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th->seq = htonl(seq);
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th->cwr = 0;
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}
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/* Following permits TCP Small Queues to work well with GSO :
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* The callback to TCP stack will be called at the time last frag
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* is freed at TX completion, and not right now when gso_skb
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* is freed by GSO engine
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*/
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if (copy_destructor) {
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int delta;
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swap(gso_skb->sk, skb->sk);
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swap(gso_skb->destructor, skb->destructor);
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sum_truesize += skb->truesize;
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delta = sum_truesize - gso_skb->truesize;
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/* In some pathological cases, delta can be negative.
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* We need to either use refcount_add() or refcount_sub_and_test()
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*/
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if (likely(delta >= 0))
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refcount_add(delta, &skb->sk->sk_wmem_alloc);
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else
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WARN_ON_ONCE(refcount_sub_and_test(-delta, &skb->sk->sk_wmem_alloc));
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}
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delta = (__force __wsum)htonl(oldlen +
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(skb_tail_pointer(skb) -
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skb_transport_header(skb)) +
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skb->data_len);
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th->check = ~csum_fold(csum_add(csum_unfold(th->check), delta));
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if (skb->ip_summed == CHECKSUM_PARTIAL)
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gso_reset_checksum(skb, ~th->check);
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else
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th->check = gso_make_checksum(skb, ~th->check);
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out:
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return segs;
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}
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struct sk_buff *tcp_gro_lookup(struct list_head *head, struct tcphdr *th)
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{
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struct tcphdr *th2;
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struct sk_buff *p;
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list_for_each_entry(p, head, list) {
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if (!NAPI_GRO_CB(p)->same_flow)
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continue;
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th2 = tcp_hdr(p);
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if (*(u32 *)&th->source ^ *(u32 *)&th2->source) {
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NAPI_GRO_CB(p)->same_flow = 0;
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continue;
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}
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return p;
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}
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return NULL;
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}
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struct tcphdr *tcp_gro_pull_header(struct sk_buff *skb)
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{
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unsigned int thlen, hlen, off;
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struct tcphdr *th;
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off = skb_gro_offset(skb);
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hlen = off + sizeof(*th);
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th = skb_gro_header(skb, hlen, off);
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if (unlikely(!th))
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return NULL;
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thlen = th->doff * 4;
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if (thlen < sizeof(*th))
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return NULL;
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hlen = off + thlen;
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if (!skb_gro_may_pull(skb, hlen)) {
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th = skb_gro_header_slow(skb, hlen, off);
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if (unlikely(!th))
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return NULL;
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}
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skb_gro_pull(skb, thlen);
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return th;
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}
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struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb,
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struct tcphdr *th)
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{
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unsigned int thlen = th->doff * 4;
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struct sk_buff *pp = NULL;
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struct sk_buff *p;
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struct tcphdr *th2;
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unsigned int len;
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__be32 flags;
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unsigned int mss = 1;
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int flush = 1;
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int i;
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len = skb_gro_len(skb);
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flags = tcp_flag_word(th);
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p = tcp_gro_lookup(head, th);
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if (!p)
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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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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_word(th2)) &
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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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for (i = sizeof(*th); i < thlen; i += 4)
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flush |= *(u32 *)((u8 *)th + 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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* 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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/* If skb is a GRO packet, make sure its gso_size matches prior packet mss.
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* If it is a single frame, do not aggregate it if its length
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* is bigger than our mss.
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*/
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if (unlikely(skb_is_gso(skb)))
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flush |= (mss != skb_shinfo(skb)->gso_size);
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else
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flush |= (len - 1) >= mss;
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flush |= (ntohl(th2->seq) + skb_gro_len(p)) ^ ntohl(th->seq);
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flush |= skb_cmp_decrypted(p, skb);
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if (unlikely(NAPI_GRO_CB(p)->is_flist)) {
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flush |= (__force int)(flags ^ tcp_flag_word(th2));
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flush |= skb->ip_summed != p->ip_summed;
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flush |= skb->csum_level != p->csum_level;
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flush |= NAPI_GRO_CB(p)->count >= 64;
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if (flush || skb_gro_receive_list(p, skb))
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mss = 1;
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goto out_check_final;
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}
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if (flush || skb_gro_receive(p, skb)) {
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mss = 1;
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goto out_check_final;
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}
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tcp_flag_word(th2) |= flags & (TCP_FLAG_FIN | TCP_FLAG_PSH);
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out_check_final:
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/* Force a flush if last segment is smaller than mss. */
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if (unlikely(skb_is_gso(skb)))
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flush = len != NAPI_GRO_CB(skb)->count * skb_shinfo(skb)->gso_size;
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else
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flush = len < mss;
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flush |= (__force int)(flags & (TCP_FLAG_URG | TCP_FLAG_PSH |
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TCP_FLAG_RST | TCP_FLAG_SYN |
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TCP_FLAG_FIN));
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if (p && (!NAPI_GRO_CB(skb)->same_flow || flush))
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pp = p;
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NAPI_GRO_CB(skb)->flush |= (flush != 0);
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return pp;
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}
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void tcp_gro_complete(struct sk_buff *skb)
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{
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struct tcphdr *th = tcp_hdr(skb);
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struct skb_shared_info *shinfo;
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if (skb->encapsulation)
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skb->inner_transport_header = skb->transport_header;
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skb->csum_start = (unsigned char *)th - skb->head;
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skb->csum_offset = offsetof(struct tcphdr, check);
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skb->ip_summed = CHECKSUM_PARTIAL;
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shinfo = skb_shinfo(skb);
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shinfo->gso_segs = NAPI_GRO_CB(skb)->count;
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if (th->cwr)
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shinfo->gso_type |= SKB_GSO_TCP_ECN;
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}
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EXPORT_SYMBOL(tcp_gro_complete);
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static void tcp4_check_fraglist_gro(struct list_head *head, struct sk_buff *skb,
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struct tcphdr *th)
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{
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const struct iphdr *iph;
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struct sk_buff *p;
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struct sock *sk;
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struct net *net;
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int iif, sdif;
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if (likely(!(skb->dev->features & NETIF_F_GRO_FRAGLIST)))
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return;
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p = tcp_gro_lookup(head, th);
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if (p) {
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NAPI_GRO_CB(skb)->is_flist = NAPI_GRO_CB(p)->is_flist;
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return;
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}
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inet_get_iif_sdif(skb, &iif, &sdif);
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iph = skb_gro_network_header(skb);
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net = dev_net(skb->dev);
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sk = __inet_lookup_established(net, net->ipv4.tcp_death_row.hashinfo,
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iph->saddr, th->source,
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iph->daddr, ntohs(th->dest),
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iif, sdif);
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NAPI_GRO_CB(skb)->is_flist = !sk;
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if (sk)
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sock_put(sk);
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}
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INDIRECT_CALLABLE_SCOPE
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struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb)
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{
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struct tcphdr *th;
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/* Don't bother verifying checksum if we're going to flush anyway. */
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if (!NAPI_GRO_CB(skb)->flush &&
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skb_gro_checksum_validate(skb, IPPROTO_TCP,
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inet_gro_compute_pseudo))
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goto flush;
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th = tcp_gro_pull_header(skb);
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if (!th)
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goto flush;
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tcp4_check_fraglist_gro(head, skb, th);
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return tcp_gro_receive(head, skb, th);
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flush:
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NAPI_GRO_CB(skb)->flush = 1;
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return NULL;
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}
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INDIRECT_CALLABLE_SCOPE int tcp4_gro_complete(struct sk_buff *skb, int thoff)
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{
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const struct iphdr *iph = ip_hdr(skb);
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struct tcphdr *th = tcp_hdr(skb);
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if (unlikely(NAPI_GRO_CB(skb)->is_flist)) {
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skb_shinfo(skb)->gso_type |= SKB_GSO_FRAGLIST | SKB_GSO_TCPV4;
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skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
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__skb_incr_checksum_unnecessary(skb);
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return 0;
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}
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th->check = ~tcp_v4_check(skb->len - thoff, iph->saddr,
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iph->daddr, 0);
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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);
|
|
|
|
tcp_gro_complete(skb);
|
|
return 0;
|
|
}
|
|
|
|
int __init tcpv4_offload_init(void)
|
|
{
|
|
net_hotdata.tcpv4_offload = (struct net_offload) {
|
|
.callbacks = {
|
|
.gso_segment = tcp4_gso_segment,
|
|
.gro_receive = tcp4_gro_receive,
|
|
.gro_complete = tcp4_gro_complete,
|
|
},
|
|
};
|
|
return inet_add_offload(&net_hotdata.tcpv4_offload, IPPROTO_TCP);
|
|
}
|