[NET] IPV4: Fix whitespace errors.
[safe/jmp/linux-2.6] / net / ipv4 / tcp_output.c
index 602e705..cebe9aa 100644 (file)
 #include <linux/smp_lock.h>
 
 /* People can turn this off for buggy TCP's found in printers etc. */
-int sysctl_tcp_retrans_collapse = 1;
+int sysctl_tcp_retrans_collapse __read_mostly = 1;
+
+/* People can turn this on to  work with those rare, broken TCPs that
+ * interpret the window field as a signed quantity.
+ */
+int sysctl_tcp_workaround_signed_windows __read_mostly = 0;
 
 /* This limits the percentage of the congestion window which we
  * will allow a single TSO frame to consume.  Building TSO frames
  * which are too large can cause TCP streams to be bursty.
  */
-int sysctl_tcp_tso_win_divisor = 3;
+int sysctl_tcp_tso_win_divisor __read_mostly = 3;
+
+int sysctl_tcp_mtu_probing __read_mostly = 0;
+int sysctl_tcp_base_mss __read_mostly = 512;
+
+/* By default, RFC2861 behavior.  */
+int sysctl_tcp_slow_start_after_idle __read_mostly = 1;
 
-static inline void update_send_head(struct sock *sk, struct tcp_sock *tp,
-                                   struct sk_buff *skb)
+static void update_send_head(struct sock *sk, struct tcp_sock *tp,
+                            struct sk_buff *skb)
 {
        sk->sk_send_head = skb->next;
        if (sk->sk_send_head == (struct sk_buff *)&sk->sk_write_queue)
@@ -124,13 +135,14 @@ static void tcp_cwnd_restart(struct sock *sk, struct dst_entry *dst)
        tp->snd_cwnd_used = 0;
 }
 
-static inline void tcp_event_data_sent(struct tcp_sock *tp,
-                                      struct sk_buff *skb, struct sock *sk)
+static void tcp_event_data_sent(struct tcp_sock *tp,
+                               struct sk_buff *skb, struct sock *sk)
 {
        struct inet_connection_sock *icsk = inet_csk(sk);
        const u32 now = tcp_time_stamp;
 
-       if (!tp->packets_out && (s32)(now - tp->lsndtime) > icsk->icsk_rto)
+       if (sysctl_tcp_slow_start_after_idle &&
+           (!tp->packets_out && (s32)(now - tp->lsndtime) > icsk->icsk_rto))
                tcp_cwnd_restart(sk, __sk_dst_get(sk));
 
        tp->lsndtime = now;
@@ -142,7 +154,7 @@ static inline void tcp_event_data_sent(struct tcp_sock *tp,
                icsk->icsk_ack.pingpong = 1;
 }
 
-static __inline__ void tcp_event_ack_sent(struct sock *sk, unsigned int pkts)
+static inline void tcp_event_ack_sent(struct sock *sk, unsigned int pkts)
 {
        tcp_dec_quickack_mode(sk, pkts);
        inet_csk_clear_xmit_timer(sk, ICSK_TIME_DACK);
@@ -171,18 +183,25 @@ void tcp_select_initial_window(int __space, __u32 mss,
                space = (space / mss) * mss;
 
        /* NOTE: offering an initial window larger than 32767
-        * will break some buggy TCP stacks. We try to be nice.
-        * If we are not window scaling, then this truncates
-        * our initial window offering to 32k. There should also
-        * be a sysctl option to stop being nice.
+        * will break some buggy TCP stacks. If the admin tells us
+        * it is likely we could be speaking with such a buggy stack
+        * we will truncate our initial window offering to 32K-1
+        * unless the remote has sent us a window scaling option,
+        * which we interpret as a sign the remote TCP is not
+        * misinterpreting the window field as a signed quantity.
         */
-       (*rcv_wnd) = min(space, MAX_TCP_WINDOW);
+       if (sysctl_tcp_workaround_signed_windows)
+               (*rcv_wnd) = min(space, MAX_TCP_WINDOW);
+       else
+               (*rcv_wnd) = space;
+
        (*rcv_wscale) = 0;
        if (wscale_ok) {
                /* Set window scaling on max possible window
-                * See RFC1323 for an explanation of the limit to 14 
+                * See RFC1323 for an explanation of the limit to 14
                 */
                space = max_t(u32, sysctl_tcp_rmem[2], sysctl_rmem_max);
+               space = min_t(u32, space, *window_clamp);
                while (space > 65535 && (*rcv_wscale) < 14) {
                        space >>= 1;
                        (*rcv_wscale)++;
@@ -212,7 +231,7 @@ void tcp_select_initial_window(int __space, __u32 mss,
  * value can be stuffed directly into th->window for an outgoing
  * frame.
  */
-static __inline__ u16 tcp_select_window(struct sock *sk)
+static u16 tcp_select_window(struct sock *sk)
 {
        struct tcp_sock *tp = tcp_sk(sk);
        u32 cur_win = tcp_receive_window(tp);
@@ -235,7 +254,7 @@ static __inline__ u16 tcp_select_window(struct sock *sk)
        /* Make sure we do not exceed the maximum possible
         * scaled window.
         */
-       if (!tp->rx_opt.rcv_wscale)
+       if (!tp->rx_opt.rcv_wscale && sysctl_tcp_workaround_signed_windows)
                new_win = min(new_win, MAX_TCP_WINDOW);
        else
                new_win = min(new_win, (65535U << tp->rx_opt.rcv_wscale));
@@ -250,6 +269,111 @@ static __inline__ u16 tcp_select_window(struct sock *sk)
        return new_win;
 }
 
+static void tcp_build_and_update_options(__be32 *ptr, struct tcp_sock *tp,
+                                        __u32 tstamp, __u8 **md5_hash)
+{
+       if (tp->rx_opt.tstamp_ok) {
+               *ptr++ = htonl((TCPOPT_NOP << 24) |
+                              (TCPOPT_NOP << 16) |
+                              (TCPOPT_TIMESTAMP << 8) |
+                              TCPOLEN_TIMESTAMP);
+               *ptr++ = htonl(tstamp);
+               *ptr++ = htonl(tp->rx_opt.ts_recent);
+       }
+       if (tp->rx_opt.eff_sacks) {
+               struct tcp_sack_block *sp = tp->rx_opt.dsack ? tp->duplicate_sack : tp->selective_acks;
+               int this_sack;
+
+               *ptr++ = htonl((TCPOPT_NOP  << 24) |
+                              (TCPOPT_NOP  << 16) |
+                              (TCPOPT_SACK <<  8) |
+                              (TCPOLEN_SACK_BASE + (tp->rx_opt.eff_sacks *
+                                                    TCPOLEN_SACK_PERBLOCK)));
+               for(this_sack = 0; this_sack < tp->rx_opt.eff_sacks; this_sack++) {
+                       *ptr++ = htonl(sp[this_sack].start_seq);
+                       *ptr++ = htonl(sp[this_sack].end_seq);
+               }
+               if (tp->rx_opt.dsack) {
+                       tp->rx_opt.dsack = 0;
+                       tp->rx_opt.eff_sacks--;
+               }
+       }
+#ifdef CONFIG_TCP_MD5SIG
+       if (md5_hash) {
+               *ptr++ = htonl((TCPOPT_NOP << 24) |
+                              (TCPOPT_NOP << 16) |
+                              (TCPOPT_MD5SIG << 8) |
+                              TCPOLEN_MD5SIG);
+               *md5_hash = (__u8 *)ptr;
+       }
+#endif
+}
+
+/* Construct a tcp options header for a SYN or SYN_ACK packet.
+ * If this is every changed make sure to change the definition of
+ * MAX_SYN_SIZE to match the new maximum number of options that you
+ * can generate.
+ *
+ * Note - that with the RFC2385 TCP option, we make room for the
+ * 16 byte MD5 hash. This will be filled in later, so the pointer for the
+ * location to be filled is passed back up.
+ */
+static void tcp_syn_build_options(__be32 *ptr, int mss, int ts, int sack,
+                                 int offer_wscale, int wscale, __u32 tstamp,
+                                 __u32 ts_recent, __u8 **md5_hash)
+{
+       /* We always get an MSS option.
+        * The option bytes which will be seen in normal data
+        * packets should timestamps be used, must be in the MSS
+        * advertised.  But we subtract them from tp->mss_cache so
+        * that calculations in tcp_sendmsg are simpler etc.
+        * So account for this fact here if necessary.  If we
+        * don't do this correctly, as a receiver we won't
+        * recognize data packets as being full sized when we
+        * should, and thus we won't abide by the delayed ACK
+        * rules correctly.
+        * SACKs don't matter, we never delay an ACK when we
+        * have any of those going out.
+        */
+       *ptr++ = htonl((TCPOPT_MSS << 24) | (TCPOLEN_MSS << 16) | mss);
+       if (ts) {
+               if(sack)
+                       *ptr++ = htonl((TCPOPT_SACK_PERM << 24) |
+                                      (TCPOLEN_SACK_PERM << 16) |
+                                      (TCPOPT_TIMESTAMP << 8) |
+                                      TCPOLEN_TIMESTAMP);
+               else
+                       *ptr++ = htonl((TCPOPT_NOP << 24) |
+                                      (TCPOPT_NOP << 16) |
+                                      (TCPOPT_TIMESTAMP << 8) |
+                                      TCPOLEN_TIMESTAMP);
+               *ptr++ = htonl(tstamp);         /* TSVAL */
+               *ptr++ = htonl(ts_recent);      /* TSECR */
+       } else if(sack)
+               *ptr++ = htonl((TCPOPT_NOP << 24) |
+                              (TCPOPT_NOP << 16) |
+                              (TCPOPT_SACK_PERM << 8) |
+                              TCPOLEN_SACK_PERM);
+       if (offer_wscale)
+               *ptr++ = htonl((TCPOPT_NOP << 24) |
+                              (TCPOPT_WINDOW << 16) |
+                              (TCPOLEN_WINDOW << 8) |
+                              (wscale));
+#ifdef CONFIG_TCP_MD5SIG
+       /*
+        * If MD5 is enabled, then we set the option, and include the size
+        * (always 18). The actual MD5 hash is added just before the
+        * packet is sent.
+        */
+       if (md5_hash) {
+               *ptr++ = htonl((TCPOPT_NOP << 24) |
+                              (TCPOPT_NOP << 16) |
+                              (TCPOPT_MD5SIG << 8) |
+                              TCPOLEN_MD5SIG);
+               *md5_hash = (__u8 *) ptr;
+       }
+#endif
+}
 
 /* This routine actually transmits TCP packets queued in by
  * tcp_do_sendmsg().  This is used by both the initial
@@ -262,129 +386,176 @@ static __inline__ u16 tcp_select_window(struct sock *sk)
  * We are working here with either a clone of the original
  * SKB, or a fresh unique copy made by the retransmit engine.
  */
-static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb)
+static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, gfp_t gfp_mask)
 {
-       if (skb != NULL) {
-               const struct inet_connection_sock *icsk = inet_csk(sk);
-               struct inet_sock *inet = inet_sk(sk);
-               struct tcp_sock *tp = tcp_sk(sk);
-               struct tcp_skb_cb *tcb = TCP_SKB_CB(skb);
-               int tcp_header_size = tp->tcp_header_len;
-               struct tcphdr *th;
-               int sysctl_flags;
-               int err;
+       const struct inet_connection_sock *icsk = inet_csk(sk);
+       struct inet_sock *inet;
+       struct tcp_sock *tp;
+       struct tcp_skb_cb *tcb;
+       int tcp_header_size;
+#ifdef CONFIG_TCP_MD5SIG
+       struct tcp_md5sig_key *md5;
+       __u8 *md5_hash_location;
+#endif
+       struct tcphdr *th;
+       int sysctl_flags;
+       int err;
+
+       BUG_ON(!skb || !tcp_skb_pcount(skb));
 
-               BUG_ON(!tcp_skb_pcount(skb));
+       /* If congestion control is doing timestamping, we must
+        * take such a timestamp before we potentially clone/copy.
+        */
+       if (icsk->icsk_ca_ops->rtt_sample)
+               __net_timestamp(skb);
+
+       if (likely(clone_it)) {
+               if (unlikely(skb_cloned(skb)))
+                       skb = pskb_copy(skb, gfp_mask);
+               else
+                       skb = skb_clone(skb, gfp_mask);
+               if (unlikely(!skb))
+                       return -ENOBUFS;
+       }
+
+       inet = inet_sk(sk);
+       tp = tcp_sk(sk);
+       tcb = TCP_SKB_CB(skb);
+       tcp_header_size = tp->tcp_header_len;
 
 #define SYSCTL_FLAG_TSTAMPS    0x1
 #define SYSCTL_FLAG_WSCALE     0x2
 #define SYSCTL_FLAG_SACK       0x4
 
-               /* If congestion control is doing timestamping */
-               if (icsk->icsk_ca_ops->rtt_sample)
-                       __net_timestamp(skb);
-
-               sysctl_flags = 0;
-               if (tcb->flags & TCPCB_FLAG_SYN) {
-                       tcp_header_size = sizeof(struct tcphdr) + TCPOLEN_MSS;
-                       if(sysctl_tcp_timestamps) {
-                               tcp_header_size += TCPOLEN_TSTAMP_ALIGNED;
-                               sysctl_flags |= SYSCTL_FLAG_TSTAMPS;
-                       }
-                       if(sysctl_tcp_window_scaling) {
-                               tcp_header_size += TCPOLEN_WSCALE_ALIGNED;
-                               sysctl_flags |= SYSCTL_FLAG_WSCALE;
-                       }
-                       if(sysctl_tcp_sack) {
-                               sysctl_flags |= SYSCTL_FLAG_SACK;
-                               if(!(sysctl_flags & SYSCTL_FLAG_TSTAMPS))
-                                       tcp_header_size += TCPOLEN_SACKPERM_ALIGNED;
-                       }
-               } else if (tp->rx_opt.eff_sacks) {
-                       /* A SACK is 2 pad bytes, a 2 byte header, plus
-                        * 2 32-bit sequence numbers for each SACK block.
-                        */
-                       tcp_header_size += (TCPOLEN_SACK_BASE_ALIGNED +
-                                           (tp->rx_opt.eff_sacks * TCPOLEN_SACK_PERBLOCK));
+       sysctl_flags = 0;
+       if (unlikely(tcb->flags & TCPCB_FLAG_SYN)) {
+               tcp_header_size = sizeof(struct tcphdr) + TCPOLEN_MSS;
+               if(sysctl_tcp_timestamps) {
+                       tcp_header_size += TCPOLEN_TSTAMP_ALIGNED;
+                       sysctl_flags |= SYSCTL_FLAG_TSTAMPS;
                }
-               
-               if (tcp_packets_in_flight(tp) == 0)
-                       tcp_ca_event(sk, CA_EVENT_TX_START);
-
-               th = (struct tcphdr *) skb_push(skb, tcp_header_size);
-               skb->h.th = th;
-               skb_set_owner_w(skb, sk);
-
-               /* Build TCP header and checksum it. */
-               th->source              = inet->sport;
-               th->dest                = inet->dport;
-               th->seq                 = htonl(tcb->seq);
-               th->ack_seq             = htonl(tp->rcv_nxt);
-               *(((__u16 *)th) + 6)    = htons(((tcp_header_size >> 2) << 12) | tcb->flags);
-               if (tcb->flags & TCPCB_FLAG_SYN) {
-                       /* RFC1323: The window in SYN & SYN/ACK segments
-                        * is never scaled.
-                        */
-                       th->window      = htons(tp->rcv_wnd);
-               } else {
-                       th->window      = htons(tcp_select_window(sk));
+               if (sysctl_tcp_window_scaling) {
+                       tcp_header_size += TCPOLEN_WSCALE_ALIGNED;
+                       sysctl_flags |= SYSCTL_FLAG_WSCALE;
                }
-               th->check               = 0;
-               th->urg_ptr             = 0;
-
-               if (tp->urg_mode &&
-                   between(tp->snd_up, tcb->seq+1, tcb->seq+0xFFFF)) {
-                       th->urg_ptr             = htons(tp->snd_up-tcb->seq);
-                       th->urg                 = 1;
+               if (sysctl_tcp_sack) {
+                       sysctl_flags |= SYSCTL_FLAG_SACK;
+                       if (!(sysctl_flags & SYSCTL_FLAG_TSTAMPS))
+                               tcp_header_size += TCPOLEN_SACKPERM_ALIGNED;
                }
+       } else if (unlikely(tp->rx_opt.eff_sacks)) {
+               /* A SACK is 2 pad bytes, a 2 byte header, plus
+                * 2 32-bit sequence numbers for each SACK block.
+                */
+               tcp_header_size += (TCPOLEN_SACK_BASE_ALIGNED +
+                                   (tp->rx_opt.eff_sacks *
+                                    TCPOLEN_SACK_PERBLOCK));
+       }
 
-               if (tcb->flags & TCPCB_FLAG_SYN) {
-                       tcp_syn_build_options((__u32 *)(th + 1),
-                                             tcp_advertise_mss(sk),
-                                             (sysctl_flags & SYSCTL_FLAG_TSTAMPS),
-                                             (sysctl_flags & SYSCTL_FLAG_SACK),
-                                             (sysctl_flags & SYSCTL_FLAG_WSCALE),
-                                             tp->rx_opt.rcv_wscale,
-                                             tcb->when,
-                                             tp->rx_opt.ts_recent);
-               } else {
-                       tcp_build_and_update_options((__u32 *)(th + 1),
-                                                    tp, tcb->when);
+       if (tcp_packets_in_flight(tp) == 0)
+               tcp_ca_event(sk, CA_EVENT_TX_START);
 
-                       TCP_ECN_send(sk, tp, skb, tcp_header_size);
-               }
-               tp->af_specific->send_check(sk, th, skb->len, skb);
+#ifdef CONFIG_TCP_MD5SIG
+       /*
+        * Are we doing MD5 on this segment? If so - make
+        * room for it.
+        */
+       md5 = tp->af_specific->md5_lookup(sk, sk);
+       if (md5)
+               tcp_header_size += TCPOLEN_MD5SIG_ALIGNED;
+#endif
+
+       th = (struct tcphdr *) skb_push(skb, tcp_header_size);
+       skb->h.th = th;
+       skb_set_owner_w(skb, sk);
+
+       /* Build TCP header and checksum it. */
+       th->source              = inet->sport;
+       th->dest                = inet->dport;
+       th->seq                 = htonl(tcb->seq);
+       th->ack_seq             = htonl(tp->rcv_nxt);
+       *(((__be16 *)th) + 6)   = htons(((tcp_header_size >> 2) << 12) |
+                                       tcb->flags);
+
+       if (unlikely(tcb->flags & TCPCB_FLAG_SYN)) {
+               /* RFC1323: The window in SYN & SYN/ACK segments
+                * is never scaled.
+                */
+               th->window      = htons(tp->rcv_wnd);
+       } else {
+               th->window      = htons(tcp_select_window(sk));
+       }
+       th->check               = 0;
+       th->urg_ptr             = 0;
+
+       if (unlikely(tp->urg_mode &&
+                    between(tp->snd_up, tcb->seq+1, tcb->seq+0xFFFF))) {
+               th->urg_ptr             = htons(tp->snd_up-tcb->seq);
+               th->urg                 = 1;
+       }
+
+       if (unlikely(tcb->flags & TCPCB_FLAG_SYN)) {
+               tcp_syn_build_options((__be32 *)(th + 1),
+                                     tcp_advertise_mss(sk),
+                                     (sysctl_flags & SYSCTL_FLAG_TSTAMPS),
+                                     (sysctl_flags & SYSCTL_FLAG_SACK),
+                                     (sysctl_flags & SYSCTL_FLAG_WSCALE),
+                                     tp->rx_opt.rcv_wscale,
+                                     tcb->when,
+                                     tp->rx_opt.ts_recent,
+
+#ifdef CONFIG_TCP_MD5SIG
+                                     md5 ? &md5_hash_location :
+#endif
+                                     NULL);
+       } else {
+               tcp_build_and_update_options((__be32 *)(th + 1),
+                                            tp, tcb->when,
+#ifdef CONFIG_TCP_MD5SIG
+                                            md5 ? &md5_hash_location :
+#endif
+                                            NULL);
+               TCP_ECN_send(sk, tp, skb, tcp_header_size);
+       }
+
+#ifdef CONFIG_TCP_MD5SIG
+       /* Calculate the MD5 hash, as we have all we need now */
+       if (md5) {
+               tp->af_specific->calc_md5_hash(md5_hash_location,
+                                              md5,
+                                              sk, NULL, NULL,
+                                              skb->h.th,
+                                              sk->sk_protocol,
+                                              skb->len);
+       }
+#endif
+
+       icsk->icsk_af_ops->send_check(sk, skb->len, skb);
 
-               if (tcb->flags & TCPCB_FLAG_ACK)
-                       tcp_event_ack_sent(sk, tcp_skb_pcount(skb));
+       if (likely(tcb->flags & TCPCB_FLAG_ACK))
+               tcp_event_ack_sent(sk, tcp_skb_pcount(skb));
 
-               if (skb->len != tcp_header_size)
-                       tcp_event_data_sent(tp, skb, sk);
+       if (skb->len != tcp_header_size)
+               tcp_event_data_sent(tp, skb, sk);
 
+       if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq)
                TCP_INC_STATS(TCP_MIB_OUTSEGS);
 
-               err = tp->af_specific->queue_xmit(skb, 0);
-               if (err <= 0)
-                       return err;
+       err = icsk->icsk_af_ops->queue_xmit(skb, 0);
+       if (likely(err <= 0))
+               return err;
 
-               tcp_enter_cwr(sk);
+       tcp_enter_cwr(sk);
+
+       return net_xmit_eval(err);
 
-               /* NET_XMIT_CN is special. It does not guarantee,
-                * that this packet is lost. It tells that device
-                * is about to start to drop packets or already
-                * drops some packets of the same priority and
-                * invokes us to send less aggressively.
-                */
-               return err == NET_XMIT_CN ? 0 : err;
-       }
-       return -ENOBUFS;
 #undef SYSCTL_FLAG_TSTAMPS
 #undef SYSCTL_FLAG_WSCALE
 #undef SYSCTL_FLAG_SACK
 }
 
 
-/* This routine just queue's the buffer 
+/* This routine just queue's the buffer
  *
  * NOTE: probe0 timer is not checked, do not forget tcp_push_pending_frames,
  * otherwise socket can stall.
@@ -406,26 +577,27 @@ static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb)
 
 static void tcp_set_skb_tso_segs(struct sock *sk, struct sk_buff *skb, unsigned int mss_now)
 {
-       if (skb->len <= mss_now ||
-           !(sk->sk_route_caps & NETIF_F_TSO)) {
+       if (skb->len <= mss_now || !sk_can_gso(sk)) {
                /* Avoid the costly divide in the normal
                 * non-TSO case.
                 */
-               skb_shinfo(skb)->tso_segs = 1;
-               skb_shinfo(skb)->tso_size = 0;
+               skb_shinfo(skb)->gso_segs = 1;
+               skb_shinfo(skb)->gso_size = 0;
+               skb_shinfo(skb)->gso_type = 0;
        } else {
                unsigned int factor;
 
                factor = skb->len + (mss_now - 1);
                factor /= mss_now;
-               skb_shinfo(skb)->tso_segs = factor;
-               skb_shinfo(skb)->tso_size = mss_now;
+               skb_shinfo(skb)->gso_segs = factor;
+               skb_shinfo(skb)->gso_size = mss_now;
+               skb_shinfo(skb)->gso_type = sk->sk_gso_type;
        }
 }
 
 /* Function to create two new TCP segments.  Shrinks the given segment
  * to the specified size and appends a new segment with the rest of the
- * packet to the list.  This won't be called frequently, I hope. 
+ * packet to the list.  This won't be called frequently, I hope.
  * Remember, these are still headerless SKBs at this point.
  */
 int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss_now)
@@ -433,9 +605,12 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss
        struct tcp_sock *tp = tcp_sk(sk);
        struct sk_buff *buff;
        int nsize, old_factor;
+       int nlen;
        u16 flags;
 
        BUG_ON(len > skb->len);
+
+       clear_all_retrans_hints(tp);
        nsize = skb_headlen(skb) - len;
        if (nsize < 0)
                nsize = 0;
@@ -449,7 +624,11 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss
        buff = sk_stream_alloc_skb(sk, nsize, GFP_ATOMIC);
        if (buff == NULL)
                return -ENOMEM; /* We'll just try again later. */
+
        sk_charge_skb(sk, buff);
+       nlen = skb->len - len - nsize;
+       buff->truesize += nlen;
+       skb->truesize -= nlen;
 
        /* Correct the sequence numbers. */
        TCP_SKB_CB(buff)->seq = TCP_SKB_CB(skb)->seq + len;
@@ -463,7 +642,7 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss
        TCP_SKB_CB(buff)->sacked = TCP_SKB_CB(skb)->sacked;
        TCP_SKB_CB(skb)->sacked &= ~TCPCB_AT_TAIL;
 
-       if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_HW) {
+       if (!skb_shinfo(skb)->nr_frags && skb->ip_summed != CHECKSUM_PARTIAL) {
                /* Copy and checksum data tail into the new buffer. */
                buff->csum = csum_partial_copy_nocheck(skb->data + len, skb_put(buff, nsize),
                                                       nsize, 0);
@@ -472,7 +651,7 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss
 
                skb->csum = csum_block_sub(skb->csum, buff->csum, len);
        } else {
-               skb->ip_summed = CHECKSUM_HW;
+               skb->ip_summed = CHECKSUM_PARTIAL;
                skb_split(skb, buff, len);
        }
 
@@ -535,7 +714,7 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss
  * eventually). The difference is that pulled data not copied, but
  * immediately discarded.
  */
-static unsigned char *__pskb_trim_head(struct sk_buff *skb, int len)
+static void __pskb_trim_head(struct sk_buff *skb, int len)
 {
        int i, k, eat;
 
@@ -560,7 +739,6 @@ static unsigned char *__pskb_trim_head(struct sk_buff *skb, int len)
        skb->tail = skb->data;
        skb->data_len -= len;
        skb->len = skb->data_len;
-       return skb->tail;
 }
 
 int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
@@ -569,15 +747,14 @@ int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
            pskb_expand_head(skb, 0, 0, GFP_ATOMIC))
                return -ENOMEM;
 
-       if (len <= skb_headlen(skb)) {
+       /* If len == headlen, we avoid __skb_pull to preserve alignment. */
+       if (unlikely(len < skb_headlen(skb)))
                __skb_pull(skb, len);
-       } else {
-               if (__pskb_trim_head(skb, len-skb_headlen(skb)) == NULL)
-                       return -ENOMEM;
-       }
+       else
+               __pskb_trim_head(skb, len - skb_headlen(skb));
 
        TCP_SKB_CB(skb)->seq += len;
-       skb->ip_summed = CHECKSUM_HW;
+       skb->ip_summed = CHECKSUM_PARTIAL;
 
        skb->truesize        -= len;
        sk->sk_wmem_queued   -= len;
@@ -593,6 +770,62 @@ int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
        return 0;
 }
 
+/* Not accounting for SACKs here. */
+int tcp_mtu_to_mss(struct sock *sk, int pmtu)
+{
+       struct tcp_sock *tp = tcp_sk(sk);
+       struct inet_connection_sock *icsk = inet_csk(sk);
+       int mss_now;
+
+       /* Calculate base mss without TCP options:
+          It is MMS_S - sizeof(tcphdr) of rfc1122
+        */
+       mss_now = pmtu - icsk->icsk_af_ops->net_header_len - sizeof(struct tcphdr);
+
+       /* Clamp it (mss_clamp does not include tcp options) */
+       if (mss_now > tp->rx_opt.mss_clamp)
+               mss_now = tp->rx_opt.mss_clamp;
+
+       /* Now subtract optional transport overhead */
+       mss_now -= icsk->icsk_ext_hdr_len;
+
+       /* Then reserve room for full set of TCP options and 8 bytes of data */
+       if (mss_now < 48)
+               mss_now = 48;
+
+       /* Now subtract TCP options size, not including SACKs */
+       mss_now -= tp->tcp_header_len - sizeof(struct tcphdr);
+
+       return mss_now;
+}
+
+/* Inverse of above */
+int tcp_mss_to_mtu(struct sock *sk, int mss)
+{
+       struct tcp_sock *tp = tcp_sk(sk);
+       struct inet_connection_sock *icsk = inet_csk(sk);
+       int mtu;
+
+       mtu = mss +
+             tp->tcp_header_len +
+             icsk->icsk_ext_hdr_len +
+             icsk->icsk_af_ops->net_header_len;
+
+       return mtu;
+}
+
+void tcp_mtup_init(struct sock *sk)
+{
+       struct tcp_sock *tp = tcp_sk(sk);
+       struct inet_connection_sock *icsk = inet_csk(sk);
+
+       icsk->icsk_mtup.enabled = sysctl_tcp_mtu_probing > 1;
+       icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) +
+                              icsk->icsk_af_ops->net_header_len;
+       icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, sysctl_tcp_base_mss);
+       icsk->icsk_mtup.probe_size = 0;
+}
+
 /* This function synchronize snd mss to current pmtu/exthdr set.
 
    tp->rx_opt.user_mss is mss set by user by TCP_MAXSEG. It does NOT counts
@@ -602,7 +835,7 @@ int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
    It is minimum of user_mss and mss received with SYN.
    It also does not include TCP options.
 
-   tp->pmtu_cookie is last pmtu, seen by this function.
+   inet_csk(sk)->icsk_pmtu_cookie is last pmtu, seen by this function.
 
    tp->mss_cache is current effective sending mss, including
    all tcp options except for SACKs. It is evaluated,
@@ -612,40 +845,29 @@ int tcp_trim_head(struct sock *sk, struct sk_buff *skb, u32 len)
    NOTE1. rfc1122 clearly states that advertised MSS
    DOES NOT include either tcp or ip options.
 
-   NOTE2. tp->pmtu_cookie and tp->mss_cache are READ ONLY outside
-   this function.                      --ANK (980731)
+   NOTE2. inet_csk(sk)->icsk_pmtu_cookie and tp->mss_cache
+   are READ ONLY outside this function.                --ANK (980731)
  */
 
 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu)
 {
        struct tcp_sock *tp = tcp_sk(sk);
+       struct inet_connection_sock *icsk = inet_csk(sk);
        int mss_now;
 
-       /* Calculate base mss without TCP options:
-          It is MMS_S - sizeof(tcphdr) of rfc1122
-        */
-       mss_now = pmtu - tp->af_specific->net_header_len - sizeof(struct tcphdr);
-
-       /* Clamp it (mss_clamp does not include tcp options) */
-       if (mss_now > tp->rx_opt.mss_clamp)
-               mss_now = tp->rx_opt.mss_clamp;
-
-       /* Now subtract optional transport overhead */
-       mss_now -= tp->ext_header_len;
-
-       /* Then reserve room for full set of TCP options and 8 bytes of data */
-       if (mss_now < 48)
-               mss_now = 48;
+       if (icsk->icsk_mtup.search_high > pmtu)
+               icsk->icsk_mtup.search_high = pmtu;
 
-       /* Now subtract TCP options size, not including SACKs */
-       mss_now -= tp->tcp_header_len - sizeof(struct tcphdr);
+       mss_now = tcp_mtu_to_mss(sk, pmtu);
 
        /* Bound mss with half of window */
        if (tp->max_window && mss_now > (tp->max_window>>1))
                mss_now = max((tp->max_window>>1), 68U - tp->tcp_header_len);
 
        /* And store cached results */
-       tp->pmtu_cookie = pmtu;
+       icsk->icsk_pmtu_cookie = pmtu;
+       if (icsk->icsk_mtup.enabled)
+               mss_now = min(mss_now, tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low));
        tp->mss_cache = mss_now;
 
        return mss_now;
@@ -668,14 +890,12 @@ unsigned int tcp_current_mss(struct sock *sk, int large_allowed)
 
        mss_now = tp->mss_cache;
 
-       if (large_allowed &&
-           (sk->sk_route_caps & NETIF_F_TSO) &&
-           !tp->urg_mode)
+       if (large_allowed && sk_can_gso(sk) && !tp->urg_mode)
                doing_tso = 1;
 
        if (dst) {
                u32 mtu = dst_mtu(dst);
-               if (mtu != tp->pmtu_cookie)
+               if (mtu != inet_csk(sk)->icsk_pmtu_cookie)
                        mss_now = tcp_sync_mss(sk, mtu);
        }
 
@@ -683,12 +903,18 @@ unsigned int tcp_current_mss(struct sock *sk, int large_allowed)
                mss_now -= (TCPOLEN_SACK_BASE_ALIGNED +
                            (tp->rx_opt.eff_sacks * TCPOLEN_SACK_PERBLOCK));
 
+#ifdef CONFIG_TCP_MD5SIG
+       if (tp->af_specific->md5_lookup(sk, sk))
+               mss_now -= TCPOLEN_MD5SIG_ALIGNED;
+#endif
+
        xmit_size_goal = mss_now;
 
        if (doing_tso) {
-               xmit_size_goal = 65535 -
-                       tp->af_specific->net_header_len -
-                       tp->ext_header_len - tp->tcp_header_len;
+               xmit_size_goal = (65535 -
+                                 inet_csk(sk)->icsk_af_ops->net_header_len -
+                                 inet_csk(sk)->icsk_ext_hdr_len -
+                                 tp->tcp_header_len);
 
                if (tp->max_window &&
                    (xmit_size_goal > (tp->max_window >> 1)))
@@ -704,7 +930,7 @@ unsigned int tcp_current_mss(struct sock *sk, int large_allowed)
 
 /* Congestion window validation. (RFC2861) */
 
-static inline void tcp_cwnd_validate(struct sock *sk, struct tcp_sock *tp)
+static void tcp_cwnd_validate(struct sock *sk, struct tcp_sock *tp)
 {
        __u32 packets_out = tp->packets_out;
 
@@ -739,7 +965,8 @@ static inline unsigned int tcp_cwnd_test(struct tcp_sock *tp, struct sk_buff *sk
        u32 in_flight, cwnd;
 
        /* Don't be strict about the congestion window for the final FIN.  */
-       if (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN)
+       if ((TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN) &&
+           tcp_skb_pcount(skb) == 1)
                return 1;
 
        in_flight = tcp_packets_in_flight(tp);
@@ -753,13 +980,13 @@ static inline unsigned int tcp_cwnd_test(struct tcp_sock *tp, struct sk_buff *sk
 /* This must be invoked the first time we consider transmitting
  * SKB onto the wire.
  */
-static inline int tcp_init_tso_segs(struct sock *sk, struct sk_buff *skb, unsigned int mss_now)
+static int tcp_init_tso_segs(struct sock *sk, struct sk_buff *skb, unsigned int mss_now)
 {
        int tso_segs = tcp_skb_pcount(skb);
 
        if (!tso_segs ||
            (tso_segs > 1 &&
-            skb_shinfo(skb)->tso_size != mss_now)) {
+            tcp_skb_mss(skb) != mss_now)) {
                tcp_set_skb_tso_segs(sk, skb, mss_now);
                tso_segs = tcp_skb_pcount(skb);
        }
@@ -781,7 +1008,7 @@ static inline int tcp_minshall_check(const struct tcp_sock *tp)
  */
 
 static inline int tcp_nagle_check(const struct tcp_sock *tp,
-                                 const struct sk_buff *skb, 
+                                 const struct sk_buff *skb,
                                  unsigned mss_now, int nonagle)
 {
        return (skb->len < mss_now &&
@@ -851,7 +1078,7 @@ static unsigned int tcp_snd_test(struct sock *sk, struct sk_buff *skb,
        return cwnd_quota;
 }
 
-static inline int tcp_skb_is_last(const struct sock *sk, 
+static inline int tcp_skb_is_last(const struct sock *sk,
                                  const struct sk_buff *skb)
 {
        return skb->next == (struct sk_buff *)&sk->sk_write_queue;
@@ -889,7 +1116,8 @@ static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len,
        if (unlikely(buff == NULL))
                return -ENOMEM;
 
-       buff->truesize = nlen;
+       sk_charge_skb(sk, buff);
+       buff->truesize += nlen;
        skb->truesize -= nlen;
 
        /* Correct the sequence numbers. */
@@ -905,7 +1133,7 @@ static int tso_fragment(struct sock *sk, struct sk_buff *skb, unsigned int len,
        /* This packet was never sent out yet, so no SACK bits. */
        TCP_SKB_CB(buff)->sacked = 0;
 
-       buff->ip_summed = skb->ip_summed = CHECKSUM_HW;
+       buff->ip_summed = skb->ip_summed = CHECKSUM_PARTIAL;
        skb_split(skb, buff, len);
 
        /* Fix up tso_factor for both original and new SKB.  */
@@ -930,10 +1158,14 @@ static int tcp_tso_should_defer(struct sock *sk, struct tcp_sock *tp, struct sk_
        u32 send_win, cong_win, limit, in_flight;
 
        if (TCP_SKB_CB(skb)->flags & TCPCB_FLAG_FIN)
-               return 0;
+               goto send_now;
 
        if (icsk->icsk_ca_state != TCP_CA_Open)
-               return 0;
+               goto send_now;
+
+       /* Defer for less than two clock ticks. */
+       if (!tp->tso_deferred && ((jiffies<<1)>>1) - (tp->tso_deferred>>1) > 1)
+               goto send_now;
 
        in_flight = tcp_packets_in_flight(tp);
 
@@ -947,6 +1179,10 @@ static int tcp_tso_should_defer(struct sock *sk, struct tcp_sock *tp, struct sk_
 
        limit = min(send_win, cong_win);
 
+       /* If a full-sized TSO skb can be sent, do it. */
+       if (limit >= 65536)
+               goto send_now;
+
        if (sysctl_tcp_tso_win_divisor) {
                u32 chunk = min(tp->snd_wnd, tp->snd_cwnd * tp->mss_cache);
 
@@ -955,7 +1191,7 @@ static int tcp_tso_should_defer(struct sock *sk, struct tcp_sock *tp, struct sk_
                 */
                chunk /= sysctl_tcp_tso_win_divisor;
                if (limit >= chunk)
-                       return 0;
+                       goto send_now;
        } else {
                /* Different approach, try not to defer past a single
                 * ACK.  Receiver should ACK every other full sized
@@ -963,13 +1199,152 @@ static int tcp_tso_should_defer(struct sock *sk, struct tcp_sock *tp, struct sk_
                 * then send now.
                 */
                if (limit > tcp_max_burst(tp) * tp->mss_cache)
-                       return 0;
+                       goto send_now;
        }
 
        /* Ok, it looks like it is advisable to defer.  */
+       tp->tso_deferred = 1 | (jiffies<<1);
+
        return 1;
+
+send_now:
+       tp->tso_deferred = 0;
+       return 0;
+}
+
+/* Create a new MTU probe if we are ready.
+ * Returns 0 if we should wait to probe (no cwnd available),
+ *         1 if a probe was sent,
+ *         -1 otherwise */
+static int tcp_mtu_probe(struct sock *sk)
+{
+       struct tcp_sock *tp = tcp_sk(sk);
+       struct inet_connection_sock *icsk = inet_csk(sk);
+       struct sk_buff *skb, *nskb, *next;
+       int len;
+       int probe_size;
+       unsigned int pif;
+       int copy;
+       int mss_now;
+
+       /* Not currently probing/verifying,
+        * not in recovery,
+        * have enough cwnd, and
+        * not SACKing (the variable headers throw things off) */
+       if (!icsk->icsk_mtup.enabled ||
+           icsk->icsk_mtup.probe_size ||
+           inet_csk(sk)->icsk_ca_state != TCP_CA_Open ||
+           tp->snd_cwnd < 11 ||
+           tp->rx_opt.eff_sacks)
+               return -1;
+
+       /* Very simple search strategy: just double the MSS. */
+       mss_now = tcp_current_mss(sk, 0);
+       probe_size = 2*tp->mss_cache;
+       if (probe_size > tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_high)) {
+               /* TODO: set timer for probe_converge_event */
+               return -1;
+       }
+
+       /* Have enough data in the send queue to probe? */
+       len = 0;
+       if ((skb = sk->sk_send_head) == NULL)
+               return -1;
+       while ((len += skb->len) < probe_size && !tcp_skb_is_last(sk, skb))
+               skb = skb->next;
+       if (len < probe_size)
+               return -1;
+
+       /* Receive window check. */
+       if (after(TCP_SKB_CB(skb)->seq + probe_size, tp->snd_una + tp->snd_wnd)) {
+               if (tp->snd_wnd < probe_size)
+                       return -1;
+               else
+                       return 0;
+       }
+
+       /* Do we need to wait to drain cwnd? */
+       pif = tcp_packets_in_flight(tp);
+       if (pif + 2 > tp->snd_cwnd) {
+               /* With no packets in flight, don't stall. */
+               if (pif == 0)
+                       return -1;
+               else
+                       return 0;
+       }
+
+       /* We're allowed to probe.  Build it now. */
+       if ((nskb = sk_stream_alloc_skb(sk, probe_size, GFP_ATOMIC)) == NULL)
+               return -1;
+       sk_charge_skb(sk, nskb);
+
+       skb = sk->sk_send_head;
+       __skb_insert(nskb, skb->prev, skb, &sk->sk_write_queue);
+       sk->sk_send_head = nskb;
+
+       TCP_SKB_CB(nskb)->seq = TCP_SKB_CB(skb)->seq;
+       TCP_SKB_CB(nskb)->end_seq = TCP_SKB_CB(skb)->seq + probe_size;
+       TCP_SKB_CB(nskb)->flags = TCPCB_FLAG_ACK;
+       TCP_SKB_CB(nskb)->sacked = 0;
+       nskb->csum = 0;
+       nskb->ip_summed = skb->ip_summed;
+
+       len = 0;
+       while (len < probe_size) {
+               next = skb->next;
+
+               copy = min_t(int, skb->len, probe_size - len);
+               if (nskb->ip_summed)
+                       skb_copy_bits(skb, 0, skb_put(nskb, copy), copy);
+               else
+                       nskb->csum = skb_copy_and_csum_bits(skb, 0,
+                                        skb_put(nskb, copy), copy, nskb->csum);
+
+               if (skb->len <= copy) {
+                       /* We've eaten all the data from this skb.
+                        * Throw it away. */
+                       TCP_SKB_CB(nskb)->flags |= TCP_SKB_CB(skb)->flags;
+                       __skb_unlink(skb, &sk->sk_write_queue);
+                       sk_stream_free_skb(sk, skb);
+               } else {
+                       TCP_SKB_CB(nskb)->flags |= TCP_SKB_CB(skb)->flags &
+                                                  ~(TCPCB_FLAG_FIN|TCPCB_FLAG_PSH);
+                       if (!skb_shinfo(skb)->nr_frags) {
+                               skb_pull(skb, copy);
+                               if (skb->ip_summed != CHECKSUM_PARTIAL)
+                                       skb->csum = csum_partial(skb->data, skb->len, 0);
+                       } else {
+                               __pskb_trim_head(skb, copy);
+                               tcp_set_skb_tso_segs(sk, skb, mss_now);
+                       }
+                       TCP_SKB_CB(skb)->seq += copy;
+               }
+
+               len += copy;
+               skb = next;
+       }
+       tcp_init_tso_segs(sk, nskb, nskb->len);
+
+       /* We're ready to send.  If this fails, the probe will
+        * be resegmented into mss-sized pieces by tcp_write_xmit(). */
+       TCP_SKB_CB(nskb)->when = tcp_time_stamp;
+       if (!tcp_transmit_skb(sk, nskb, 1, GFP_ATOMIC)) {
+               /* Decrement cwnd here because we are sending
+               * effectively two packets. */
+               tp->snd_cwnd--;
+               update_send_head(sk, tp, nskb);
+
+               icsk->icsk_mtup.probe_size = tcp_mss_to_mtu(sk, nskb->len);
+               tp->mtu_probe.probe_seq_start = TCP_SKB_CB(nskb)->seq;
+               tp->mtu_probe.probe_seq_end = TCP_SKB_CB(nskb)->end_seq;
+
+               return 1;
+       }
+
+       return -1;
 }
 
+
 /* This routine writes packets to the network.  It advances the
  * send_head.  This happens as incoming acks open up the remote
  * window for us.
@@ -983,6 +1358,7 @@ static int tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle)
        struct sk_buff *skb;
        unsigned int tso_segs, sent_pkts;
        int cwnd_quota;
+       int result;
 
        /* If we are closed, the bytes will have to remain here.
         * In time closedown will finish, we empty the write queue and all
@@ -992,6 +1368,14 @@ static int tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle)
                return 0;
 
        sent_pkts = 0;
+
+       /* Do MTU probing. */
+       if ((result = tcp_mtu_probe(sk)) == 0) {
+               return 0;
+       } else if (result > 0) {
+               sent_pkts = 1;
+       }
+
        while ((skb = sk->sk_send_head)) {
                unsigned int limit;
 
@@ -1034,7 +1418,7 @@ static int tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle)
 
                TCP_SKB_CB(skb)->when = tcp_time_stamp;
 
-               if (unlikely(tcp_transmit_skb(sk, skb_clone(skb, GFP_ATOMIC))))
+               if (unlikely(tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC)))
                        break;
 
                /* Advance the send_head.  This one is sent out.
@@ -1107,7 +1491,7 @@ void tcp_push_one(struct sock *sk, unsigned int mss_now)
                /* Send it out now. */
                TCP_SKB_CB(skb)->when = tcp_time_stamp;
 
-               if (likely(!tcp_transmit_skb(sk, skb_clone(skb, sk->sk_allocation)))) {
+               if (likely(!tcp_transmit_skb(sk, skb, 1, sk->sk_allocation))) {
                        update_send_head(sk, tp, skb);
                        tcp_cwnd_validate(sk, tp);
                        return;
@@ -1117,7 +1501,7 @@ void tcp_push_one(struct sock *sk, unsigned int mss_now)
 
 /* This function returns the amount that we can raise the
  * usable window based on the following constraints
- *  
+ *
  * 1. The window can never be shrunk once it is offered (RFC 793)
  * 2. We limit memory per socket
  *
@@ -1136,12 +1520,12 @@ void tcp_push_one(struct sock *sk, unsigned int mss_now)
  * side SWS prevention criteria. The problem is that under this rule
  * a stream of single byte packets will cause the right side of the
  * window to always advance by a single byte.
- * 
+ *
  * Of course, if the sender implements sender side SWS prevention
  * then this will not be a problem.
- * 
+ *
  * BSD seems to make the following compromise:
- * 
+ *
  *     If the free space is less than the 1/4 of the maximum
  *     space available and the free space is less than 1/2 mss,
  *     then set the window to 0.
@@ -1183,7 +1567,7 @@ u32 __tcp_select_window(struct sock *sk)
        int window;
 
        if (mss > full_space)
-               mss = full_space; 
+               mss = full_space;
 
        if (free_space < full_space/2) {
                icsk->icsk_ack.quick = 0;
@@ -1260,15 +1644,18 @@ static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *skb, int m
                BUG_ON(tcp_skb_pcount(skb) != 1 ||
                       tcp_skb_pcount(next_skb) != 1);
 
-               /* Ok.  We will be able to collapse the packet. */
+               /* changing transmit queue under us so clear hints */
+               clear_all_retrans_hints(tp);
+
+               /* Ok.  We will be able to collapse the packet. */
                __skb_unlink(next_skb, &sk->sk_write_queue);
 
                memcpy(skb_put(skb, next_skb_size), next_skb->data, next_skb_size);
 
-               if (next_skb->ip_summed == CHECKSUM_HW)
-                       skb->ip_summed = CHECKSUM_HW;
+               if (next_skb->ip_summed == CHECKSUM_PARTIAL)
+                       skb->ip_summed = CHECKSUM_PARTIAL;
 
-               if (skb->ip_summed != CHECKSUM_HW)
+               if (skb->ip_summed != CHECKSUM_PARTIAL)
                        skb->csum = csum_block_add(skb->csum, next_skb->csum, skb_size);
 
                /* Update sequence range on original skb. */
@@ -1304,9 +1691,9 @@ static void tcp_retrans_try_collapse(struct sock *sk, struct sk_buff *skb, int m
 }
 
 /* Do a simple retransmit without using the backoff mechanisms in
- * tcp_timer. This is used for path mtu discovery. 
+ * tcp_timer. This is used for path mtu discovery.
  * The socket is already locked here.
- */ 
+ */
 void tcp_simple_retransmit(struct sock *sk)
 {
        const struct inet_connection_sock *icsk = inet_csk(sk);
@@ -1316,7 +1703,7 @@ void tcp_simple_retransmit(struct sock *sk)
        int lost = 0;
 
        sk_stream_for_retrans_queue(skb, sk) {
-               if (skb->len > mss && 
+               if (skb->len > mss &&
                    !(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED)) {
                        if (TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_RETRANS) {
                                TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
@@ -1330,12 +1717,14 @@ void tcp_simple_retransmit(struct sock *sk)
                }
        }
 
+       clear_all_retrans_hints(tp);
+
        if (!lost)
                return;
 
        tcp_sync_left_out(tp);
 
-       /* Don't muck with the congestion window here.
+       /* Don't muck with the congestion window here.
         * Reason is that we do not increase amount of _data_
         * in network, but units changed and effective
         * cwnd/ssthresh really reduced now.
@@ -1357,9 +1746,15 @@ void tcp_simple_retransmit(struct sock *sk)
 int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
 {
        struct tcp_sock *tp = tcp_sk(sk);
-       unsigned int cur_mss = tcp_current_mss(sk, 0);
+       struct inet_connection_sock *icsk = inet_csk(sk);
+       unsigned int cur_mss = tcp_current_mss(sk, 0);
        int err;
 
+       /* Inconslusive MTU probe */
+       if (icsk->icsk_mtup.probe_size) {
+               icsk->icsk_mtup.probe_size = 0;
+       }
+
        /* Do not sent more than we queued. 1/4 is reserved for possible
         * copying overhead: fragmentation, tunneling, mangling etc.
         */
@@ -1398,7 +1793,7 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
           (sysctl_tcp_retrans_collapse != 0))
                tcp_retrans_try_collapse(sk, skb, cur_mss);
 
-       if(tp->af_specific->rebuild_header(sk))
+       if (inet_csk(sk)->icsk_af_ops->rebuild_header(sk))
                return -EHOSTUNREACH; /* Routing failure or similar. */
 
        /* Some Solaris stacks overoptimize and ignore the FIN on a
@@ -1410,8 +1805,9 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
           tp->snd_una == (TCP_SKB_CB(skb)->end_seq - 1)) {
                if (!pskb_trim(skb, 0)) {
                        TCP_SKB_CB(skb)->seq = TCP_SKB_CB(skb)->end_seq - 1;
-                       skb_shinfo(skb)->tso_segs = 1;
-                       skb_shinfo(skb)->tso_size = 0;
+                       skb_shinfo(skb)->gso_segs = 1;
+                       skb_shinfo(skb)->gso_size = 0;
+                       skb_shinfo(skb)->gso_type = 0;
                        skb->ip_summed = CHECKSUM_NONE;
                        skb->csum = 0;
                }
@@ -1422,9 +1818,7 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb)
         */
        TCP_SKB_CB(skb)->when = tcp_time_stamp;
 
-       err = tcp_transmit_skb(sk, (skb_cloned(skb) ?
-                                   pskb_copy(skb, GFP_ATOMIC):
-                                   skb_clone(skb, GFP_ATOMIC)));
+       err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC);
 
        if (err == 0) {
                /* Update global TCP statistics. */
@@ -1468,13 +1862,25 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
        const struct inet_connection_sock *icsk = inet_csk(sk);
        struct tcp_sock *tp = tcp_sk(sk);
        struct sk_buff *skb;
-       int packet_cnt = tp->lost_out;
+       int packet_cnt;
+
+       if (tp->retransmit_skb_hint) {
+               skb = tp->retransmit_skb_hint;
+               packet_cnt = tp->retransmit_cnt_hint;
+       }else{
+               skb = sk->sk_write_queue.next;
+               packet_cnt = 0;
+       }
 
        /* First pass: retransmit lost packets. */
-       if (packet_cnt) {
-               sk_stream_for_retrans_queue(skb, sk) {
+       if (tp->lost_out) {
+               sk_stream_for_retrans_queue_from(skb, sk) {
                        __u8 sacked = TCP_SKB_CB(skb)->sacked;
 
+                       /* we could do better than to assign each time */
+                       tp->retransmit_skb_hint = skb;
+                       tp->retransmit_cnt_hint = packet_cnt;
+
                        /* Assume this retransmit will generate
                         * only one packet for congestion window
                         * calculation purposes.  This works because
@@ -1485,10 +1891,12 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
                        if (tcp_packets_in_flight(tp) >= tp->snd_cwnd)
                                return;
 
-                       if (sacked&TCPCB_LOST) {
+                       if (sacked & TCPCB_LOST) {
                                if (!(sacked&(TCPCB_SACKED_ACKED|TCPCB_SACKED_RETRANS))) {
-                                       if (tcp_retransmit_skb(sk, skb))
+                                       if (tcp_retransmit_skb(sk, skb)) {
+                                               tp->retransmit_skb_hint = NULL;
                                                return;
+                                       }
                                        if (icsk->icsk_ca_state != TCP_CA_Loss)
                                                NET_INC_STATS_BH(LINUX_MIB_TCPFASTRETRANS);
                                        else
@@ -1501,8 +1909,8 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
                                                                          TCP_RTO_MAX);
                                }
 
-                               packet_cnt -= tcp_skb_pcount(skb);
-                               if (packet_cnt <= 0)
+                               packet_cnt += tcp_skb_pcount(skb);
+                               if (packet_cnt >= tp->lost_out)
                                        break;
                        }
                }
@@ -1528,9 +1936,18 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
        if (tcp_may_send_now(sk, tp))
                return;
 
-       packet_cnt = 0;
+       if (tp->forward_skb_hint) {
+               skb = tp->forward_skb_hint;
+               packet_cnt = tp->forward_cnt_hint;
+       } else{
+               skb = sk->sk_write_queue.next;
+               packet_cnt = 0;
+       }
+
+       sk_stream_for_retrans_queue_from(skb, sk) {
+               tp->forward_cnt_hint = packet_cnt;
+               tp->forward_skb_hint = skb;
 
-       sk_stream_for_retrans_queue(skb, sk) {
                /* Similar to the retransmit loop above we
                 * can pretend that the retransmitted SKB
                 * we send out here will be composed of one
@@ -1547,8 +1964,10 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
                        continue;
 
                /* Ok, retransmit it. */
-               if (tcp_retransmit_skb(sk, skb))
+               if (tcp_retransmit_skb(sk, skb)) {
+                       tp->forward_skb_hint = NULL;
                        break;
+               }
 
                if (skb == skb_peek(&sk->sk_write_queue))
                        inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
@@ -1565,10 +1984,10 @@ void tcp_xmit_retransmit_queue(struct sock *sk)
  */
 void tcp_send_fin(struct sock *sk)
 {
-       struct tcp_sock *tp = tcp_sk(sk);       
+       struct tcp_sock *tp = tcp_sk(sk);
        struct sk_buff *skb = skb_peek_tail(&sk->sk_write_queue);
        int mss_now;
-       
+
        /* Optimization, tack on the FIN if we have a queue of
         * unsent frames.  But be careful about outgoing SACKS
         * and IP options.
@@ -1593,8 +2012,9 @@ void tcp_send_fin(struct sock *sk)
                skb->csum = 0;
                TCP_SKB_CB(skb)->flags = (TCPCB_FLAG_ACK | TCPCB_FLAG_FIN);
                TCP_SKB_CB(skb)->sacked = 0;
-               skb_shinfo(skb)->tso_segs = 1;
-               skb_shinfo(skb)->tso_size = 0;
+               skb_shinfo(skb)->gso_segs = 1;
+               skb_shinfo(skb)->gso_size = 0;
+               skb_shinfo(skb)->gso_type = 0;
 
                /* FIN eats a sequence byte, write_seq advanced by tcp_queue_skb(). */
                TCP_SKB_CB(skb)->seq = tp->write_seq;
@@ -1626,14 +2046,15 @@ void tcp_send_active_reset(struct sock *sk, gfp_t priority)
        skb->csum = 0;
        TCP_SKB_CB(skb)->flags = (TCPCB_FLAG_ACK | TCPCB_FLAG_RST);
        TCP_SKB_CB(skb)->sacked = 0;
-       skb_shinfo(skb)->tso_segs = 1;
-       skb_shinfo(skb)->tso_size = 0;
+       skb_shinfo(skb)->gso_segs = 1;
+       skb_shinfo(skb)->gso_size = 0;
+       skb_shinfo(skb)->gso_type = 0;
 
        /* Send it off. */
        TCP_SKB_CB(skb)->seq = tcp_acceptable_seq(sk, tp);
        TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq;
        TCP_SKB_CB(skb)->when = tcp_time_stamp;
-       if (tcp_transmit_skb(sk, skb))
+       if (tcp_transmit_skb(sk, skb, 0, priority))
                NET_INC_STATS(LINUX_MIB_TCPABORTFAILED);
 }
 
@@ -1668,7 +2089,7 @@ int tcp_send_synack(struct sock *sk)
                TCP_ECN_send_synack(tcp_sk(sk), skb);
        }
        TCP_SKB_CB(skb)->when = tcp_time_stamp;
-       return tcp_transmit_skb(sk, skb_clone(skb, GFP_ATOMIC));
+       return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC);
 }
 
 /*
@@ -1682,6 +2103,10 @@ struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
        struct tcphdr *th;
        int tcp_header_size;
        struct sk_buff *skb;
+#ifdef CONFIG_TCP_MD5SIG
+       struct tcp_md5sig_key *md5;
+       __u8 *md5_hash_location;
+#endif
 
        skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15, 1, GFP_ATOMIC);
        if (skb == NULL)
@@ -1697,56 +2122,80 @@ struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
                           (ireq->wscale_ok ? TCPOLEN_WSCALE_ALIGNED : 0) +
                           /* SACK_PERM is in the place of NOP NOP of TS */
                           ((ireq->sack_ok && !ireq->tstamp_ok) ? TCPOLEN_SACKPERM_ALIGNED : 0));
+
+#ifdef CONFIG_TCP_MD5SIG
+       /* Are we doing MD5 on this segment? If so - make room for it */
+       md5 = tcp_rsk(req)->af_specific->md5_lookup(sk, req);
+       if (md5)
+               tcp_header_size += TCPOLEN_MD5SIG_ALIGNED;
+#endif
        skb->h.th = th = (struct tcphdr *) skb_push(skb, tcp_header_size);
 
        memset(th, 0, sizeof(struct tcphdr));
        th->syn = 1;
        th->ack = 1;
-       if (dst->dev->features&NETIF_F_TSO)
-               ireq->ecn_ok = 0;
        TCP_ECN_make_synack(req, th);
        th->source = inet_sk(sk)->sport;
        th->dest = ireq->rmt_port;
        TCP_SKB_CB(skb)->seq = tcp_rsk(req)->snt_isn;
        TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq + 1;
        TCP_SKB_CB(skb)->sacked = 0;
-       skb_shinfo(skb)->tso_segs = 1;
-       skb_shinfo(skb)->tso_size = 0;
+       skb_shinfo(skb)->gso_segs = 1;
+       skb_shinfo(skb)->gso_size = 0;
+       skb_shinfo(skb)->gso_type = 0;
        th->seq = htonl(TCP_SKB_CB(skb)->seq);
        th->ack_seq = htonl(tcp_rsk(req)->rcv_isn + 1);
        if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */
-               __u8 rcv_wscale; 
+               __u8 rcv_wscale;
                /* Set this up on the first call only */
                req->window_clamp = tp->window_clamp ? : dst_metric(dst, RTAX_WINDOW);
                /* tcp_full_space because it is guaranteed to be the first packet */
-               tcp_select_initial_window(tcp_full_space(sk), 
+               tcp_select_initial_window(tcp_full_space(sk),
                        dst_metric(dst, RTAX_ADVMSS) - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0),
                        &req->rcv_wnd,
                        &req->window_clamp,
                        ireq->wscale_ok,
                        &rcv_wscale);
-               ireq->rcv_wscale = rcv_wscale; 
+               ireq->rcv_wscale = rcv_wscale;
        }
 
        /* RFC1323: The window in SYN & SYN/ACK segments is never scaled. */
        th->window = htons(req->rcv_wnd);
 
        TCP_SKB_CB(skb)->when = tcp_time_stamp;
-       tcp_syn_build_options((__u32 *)(th + 1), dst_metric(dst, RTAX_ADVMSS), ireq->tstamp_ok,
+       tcp_syn_build_options((__be32 *)(th + 1), dst_metric(dst, RTAX_ADVMSS), ireq->tstamp_ok,
                              ireq->sack_ok, ireq->wscale_ok, ireq->rcv_wscale,
                              TCP_SKB_CB(skb)->when,
-                             req->ts_recent);
+                             req->ts_recent,
+                             (
+#ifdef CONFIG_TCP_MD5SIG
+                              md5 ? &md5_hash_location :
+#endif
+                              NULL)
+                             );
 
        skb->csum = 0;
        th->doff = (tcp_header_size >> 2);
        TCP_INC_STATS(TCP_MIB_OUTSEGS);
+
+#ifdef CONFIG_TCP_MD5SIG
+       /* Okay, we have all we need - do the md5 hash if needed */
+       if (md5) {
+               tp->af_specific->calc_md5_hash(md5_hash_location,
+                                              md5,
+                                              NULL, dst, req,
+                                              skb->h.th, sk->sk_protocol,
+                                              skb->len);
+       }
+#endif
+
        return skb;
 }
 
-/* 
+/*
  * Do all connect socket setups that can be done AF independent.
- */ 
-static inline void tcp_connect_init(struct sock *sk)
+ */
+static void tcp_connect_init(struct sock *sk)
 {
        struct dst_entry *dst = __sk_dst_get(sk);
        struct tcp_sock *tp = tcp_sk(sk);
@@ -1758,10 +2207,16 @@ static inline void tcp_connect_init(struct sock *sk)
        tp->tcp_header_len = sizeof(struct tcphdr) +
                (sysctl_tcp_timestamps ? TCPOLEN_TSTAMP_ALIGNED : 0);
 
+#ifdef CONFIG_TCP_MD5SIG
+       if (tp->af_specific->md5_lookup(sk, sk) != NULL)
+               tp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED;
+#endif
+
        /* If user gave his TCP_MAXSEG, record it to clamp */
        if (tp->rx_opt.user_mss)
                tp->rx_opt.mss_clamp = tp->rx_opt.user_mss;
        tp->max_window = 0;
+       tcp_mtup_init(sk);
        tcp_sync_mss(sk, dst_mtu(dst));
 
        if (!tp->window_clamp)
@@ -1796,7 +2251,7 @@ static inline void tcp_connect_init(struct sock *sk)
 
 /*
  * Build a SYN and send it off.
- */ 
+ */
 int tcp_connect(struct sock *sk)
 {
        struct tcp_sock *tp = tcp_sk(sk);
@@ -1814,13 +2269,13 @@ int tcp_connect(struct sock *sk)
        TCP_SKB_CB(buff)->flags = TCPCB_FLAG_SYN;
        TCP_ECN_send_syn(sk, tp, buff);
        TCP_SKB_CB(buff)->sacked = 0;
-       skb_shinfo(buff)->tso_segs = 1;
-       skb_shinfo(buff)->tso_size = 0;
+       skb_shinfo(buff)->gso_segs = 1;
+       skb_shinfo(buff)->gso_size = 0;
+       skb_shinfo(buff)->gso_type = 0;
        buff->csum = 0;
+       tp->snd_nxt = tp->write_seq;
        TCP_SKB_CB(buff)->seq = tp->write_seq++;
        TCP_SKB_CB(buff)->end_seq = tp->write_seq;
-       tp->snd_nxt = tp->write_seq;
-       tp->pushed_seq = tp->write_seq;
 
        /* Send it off. */
        TCP_SKB_CB(buff)->when = tcp_time_stamp;
@@ -1829,7 +2284,13 @@ int tcp_connect(struct sock *sk)
        __skb_queue_tail(&sk->sk_write_queue, buff);
        sk_charge_skb(sk, buff);
        tp->packets_out += tcp_skb_pcount(buff);
-       tcp_transmit_skb(sk, skb_clone(buff, GFP_KERNEL));
+       tcp_transmit_skb(sk, buff, 1, GFP_KERNEL);
+
+       /* We change tp->snd_nxt after the tcp_transmit_skb() call
+        * in order to make this packet get counted in tcpOutSegs.
+        */
+       tp->snd_nxt = tp->write_seq;
+       tp->pushed_seq = tp->write_seq;
        TCP_INC_STATS(TCP_MIB_ACTIVEOPENS);
 
        /* Timer for repeating the SYN until an answer. */
@@ -1919,13 +2380,14 @@ void tcp_send_ack(struct sock *sk)
                buff->csum = 0;
                TCP_SKB_CB(buff)->flags = TCPCB_FLAG_ACK;
                TCP_SKB_CB(buff)->sacked = 0;
-               skb_shinfo(buff)->tso_segs = 1;
-               skb_shinfo(buff)->tso_size = 0;
+               skb_shinfo(buff)->gso_segs = 1;
+               skb_shinfo(buff)->gso_size = 0;
+               skb_shinfo(buff)->gso_type = 0;
 
                /* Send it off, this clears delayed acks for us. */
                TCP_SKB_CB(buff)->seq = TCP_SKB_CB(buff)->end_seq = tcp_acceptable_seq(sk, tp);
                TCP_SKB_CB(buff)->when = tcp_time_stamp;
-               tcp_transmit_skb(sk, buff);
+               tcp_transmit_skb(sk, buff, 0, GFP_ATOMIC);
        }
 }
 
@@ -1947,7 +2409,7 @@ static int tcp_xmit_probe_skb(struct sock *sk, int urgent)
 
        /* We don't queue it, tcp_transmit_skb() sets ownership. */
        skb = alloc_skb(MAX_TCP_HEADER, GFP_ATOMIC);
-       if (skb == NULL) 
+       if (skb == NULL)
                return -1;
 
        /* Reserve space for headers and set control bits. */
@@ -1955,8 +2417,9 @@ static int tcp_xmit_probe_skb(struct sock *sk, int urgent)
        skb->csum = 0;
        TCP_SKB_CB(skb)->flags = TCPCB_FLAG_ACK;
        TCP_SKB_CB(skb)->sacked = urgent;
-       skb_shinfo(skb)->tso_segs = 1;
-       skb_shinfo(skb)->tso_size = 0;
+       skb_shinfo(skb)->gso_segs = 1;
+       skb_shinfo(skb)->gso_size = 0;
+       skb_shinfo(skb)->gso_type = 0;
 
        /* Use a previous sequence.  This should cause the other
         * end to send an ack.  Don't queue or clone SKB, just
@@ -1965,7 +2428,7 @@ static int tcp_xmit_probe_skb(struct sock *sk, int urgent)
        TCP_SKB_CB(skb)->seq = urgent ? tp->snd_una : tp->snd_una - 1;
        TCP_SKB_CB(skb)->end_seq = TCP_SKB_CB(skb)->seq;
        TCP_SKB_CB(skb)->when = tcp_time_stamp;
-       return tcp_transmit_skb(sk, skb);
+       return tcp_transmit_skb(sk, skb, 0, GFP_ATOMIC);
 }
 
 int tcp_write_wakeup(struct sock *sk)
@@ -1998,7 +2461,7 @@ int tcp_write_wakeup(struct sock *sk)
 
                        TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_PSH;
                        TCP_SKB_CB(skb)->when = tcp_time_stamp;
-                       err = tcp_transmit_skb(sk, skb_clone(skb, GFP_ATOMIC));
+                       err = tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC);
                        if (!err) {
                                update_send_head(sk, tp, skb);
                        }
@@ -2035,7 +2498,7 @@ void tcp_send_probe0(struct sock *sk)
                if (icsk->icsk_backoff < sysctl_tcp_retries2)
                        icsk->icsk_backoff++;
                icsk->icsk_probes_out++;
-               inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 
+               inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
                                          min(icsk->icsk_rto << icsk->icsk_backoff, TCP_RTO_MAX),
                                          TCP_RTO_MAX);
        } else {
@@ -2047,7 +2510,7 @@ void tcp_send_probe0(struct sock *sk)
                 */
                if (!icsk->icsk_probes_out)
                        icsk->icsk_probes_out = 1;
-               inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 
+               inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
                                          min(icsk->icsk_rto << icsk->icsk_backoff,
                                              TCP_RESOURCE_PROBE_INTERVAL),
                                          TCP_RTO_MAX);
@@ -2059,3 +2522,4 @@ EXPORT_SYMBOL(tcp_make_synack);
 EXPORT_SYMBOL(tcp_simple_retransmit);
 EXPORT_SYMBOL(tcp_sync_mss);
 EXPORT_SYMBOL(sysctl_tcp_tso_win_divisor);
+EXPORT_SYMBOL(tcp_mtup_init);