tcp: Use SKB queue and list helpers instead of doing it by-hand.

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 90 insertions, 45 deletions

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 0fb8b441f1f9..17b89c523f9d 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -439,12 +439,14 @@ int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
                          !tp->urg_data ||
                          before(tp->urg_seq, tp->copied_seq) ||
                          !before(tp->urg_seq, tp->rcv_nxt)) {
+                        struct sk_buff *skb;
+
                         answ = tp->rcv_nxt - tp->copied_seq;
 
                         /* Subtract 1, if FIN is in queue. */
-                        if (answ && !skb_queue_empty(&sk->sk_receive_queue))
-                                answ -=
-                       tcp_hdr((struct sk_buff *)sk->sk_receive_queue.prev)->fin;
+                        skb = skb_peek_tail(&sk->sk_receive_queue);
+                        if (answ && skb)
+                                answ -= tcp_hdr(skb)->fin;
                 } else
                         answ = tp->urg_seq - tp->copied_seq;
                 release_sock(sk);
@@ -1382,11 +1384,7 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 
                 /* Next get a buffer. */
 
-                skb = skb_peek(&sk->sk_receive_queue);
-                do {
-                        if (!skb)
-                                break;
-
+                skb_queue_walk(&sk->sk_receive_queue, skb) {
                         /* Now that we have two receive queues this
                          * shouldn't happen.
                          */
@@ -1403,8 +1401,7 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                         if (tcp_hdr(skb)->fin)
                                 goto found_fin_ok;
                         WARN_ON(!(flags & MSG_PEEK));
-                        skb = skb->next;
-                } while (skb != (struct sk_buff *)&sk->sk_receive_queue);
+                }
 
                 /* Well, if we have backlog, try to process it now yet. */
 
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index eeb8a92aa416..ba34a23c1bfb 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4426,7 +4426,7 @@ drop:
                 }
                 __skb_queue_head(&tp->out_of_order_queue, skb);
         } else {
-                struct sk_buff *skb1 = tp->out_of_order_queue.prev;
+                struct sk_buff *skb1 = skb_peek_tail(&tp->out_of_order_queue);
                 u32 seq = TCP_SKB_CB(skb)->seq;
                 u32 end_seq = TCP_SKB_CB(skb)->end_seq;
 
@@ -4443,15 +4443,18 @@ drop:
                 }
 
                 /* Find place to insert this segment. */
-                do {
+                while (1) {
                         if (!after(TCP_SKB_CB(skb1)->seq, seq))
                                 break;
-                } while ((skb1 = skb1->prev) !=
-                         (struct sk_buff *)&tp->out_of_order_queue);
+                        if (skb_queue_is_first(&tp->out_of_order_queue, skb1)) {
+                                skb1 = NULL;
+                                break;
+                        }
+                        skb1 = skb_queue_prev(&tp->out_of_order_queue, skb1);
+                }
 
                 /* Do skb overlap to previous one? */
-                if (skb1 != (struct sk_buff *)&tp->out_of_order_queue &&
-                    before(seq, TCP_SKB_CB(skb1)->end_seq)) {
+                if (skb1 && before(seq, TCP_SKB_CB(skb1)->end_seq)) {
                         if (!after(end_seq, TCP_SKB_CB(skb1)->end_seq)) {
                                 /* All the bits are present. Drop. */
                                 __kfree_skb(skb);
@@ -4463,24 +4466,41 @@ drop:
                                 tcp_dsack_set(sk, seq,
                                               TCP_SKB_CB(skb1)->end_seq);
                         } else {
-                                skb1 = skb1->prev;
+                                if (skb_queue_is_first(&tp->out_of_order_queue,
+                                                       skb1))
+                                        skb1 = NULL;
+                                else
+                                        skb1 = skb_queue_prev(
+                                                &tp->out_of_order_queue,
+                                                skb1);
                         }
                 }
-                __skb_queue_after(&tp->out_of_order_queue, skb1, skb);
+                if (!skb1)
+                        __skb_queue_head(&tp->out_of_order_queue, skb);
+                else
+                        __skb_queue_after(&tp->out_of_order_queue, skb1, skb);
 
                 /* And clean segments covered by new one as whole. */
-                while ((skb1 = skb->next) !=
-                       (struct sk_buff *)&tp->out_of_order_queue &&
-                       after(end_seq, TCP_SKB_CB(skb1)->seq)) {
-                        if (before(end_seq, TCP_SKB_CB(skb1)->end_seq)) {
+                if (skb1 && !skb_queue_is_last(&tp->out_of_order_queue, skb1)) {
+                        struct sk_buff *n;
+
+                        skb1 = skb_queue_next(&tp->out_of_order_queue, skb1);
+                        skb_queue_walk_from_safe(&tp->out_of_order_queue,
+                                                 skb1, n) {
+                                if (!after(end_seq, TCP_SKB_CB(skb1)->seq))
+                                        break;
+                                if (before(end_seq,
+                                           TCP_SKB_CB(skb1)->end_seq)) {
+                                        tcp_dsack_extend(sk,
+                                                         TCP_SKB_CB(skb1)->seq,
+                                                         end_seq);
+                                        break;
+                                }
+                                __skb_unlink(skb1, &tp->out_of_order_queue);
                                 tcp_dsack_extend(sk, TCP_SKB_CB(skb1)->seq,
-                                                 end_seq);
-                                break;
+                                                 TCP_SKB_CB(skb1)->end_seq);
+                                __kfree_skb(skb1);
                         }
-                        __skb_unlink(skb1, &tp->out_of_order_queue);
-                        tcp_dsack_extend(sk, TCP_SKB_CB(skb1)->seq,
-                                         TCP_SKB_CB(skb1)->end_seq);
-                        __kfree_skb(skb1);
                 }
 
 add_sack:
@@ -4492,7 +4512,10 @@ add_sack:
 static struct sk_buff *tcp_collapse_one(struct sock *sk, struct sk_buff *skb,
                                         struct sk_buff_head *list)
 {
-        struct sk_buff *next = skb->next;
+        struct sk_buff *next = NULL;
+
+        if (!skb_queue_is_last(list, skb))
+                next = skb_queue_next(list, skb);
 
         __skb_unlink(skb, list);
         __kfree_skb(skb);
@@ -4503,6 +4526,9 @@ static struct sk_buff *tcp_collapse_one(struct sock *sk, struct sk_buff *skb,
 
 /* Collapse contiguous sequence of skbs head..tail with
  * sequence numbers start..end.
+ *
+ * If tail is NULL, this means until the end of the list.
+ *
  * Segments with FIN/SYN are not collapsed (only because this
  * simplifies code)
  */
@@ -4511,15 +4537,23 @@ tcp_collapse(struct sock *sk, struct sk_buff_head *list,
              struct sk_buff *head, struct sk_buff *tail,
              u32 start, u32 end)
 {
-        struct sk_buff *skb;
+        struct sk_buff *skb, *n;
+        bool end_of_skbs;
 
         /* First, check that queue is collapsible and find
          * the point where collapsing can be useful. */
-        for (skb = head; skb != tail;) {
+        skb = head;
+restart:
+        end_of_skbs = true;
+        skb_queue_walk_from_safe(list, skb, n) {
+                if (skb == tail)
+                        break;
                 /* No new bits? It is possible on ofo queue. */
                 if (!before(start, TCP_SKB_CB(skb)->end_seq)) {
                         skb = tcp_collapse_one(sk, skb, list);
-                        continue;
+                        if (!skb)
+                                break;
+                        goto restart;
                 }
 
                 /* The first skb to collapse is:
@@ -4529,16 +4563,24 @@ tcp_collapse(struct sock *sk, struct sk_buff_head *list,
                  */
                 if (!tcp_hdr(skb)->syn && !tcp_hdr(skb)->fin &&
                     (tcp_win_from_space(skb->truesize) > skb->len ||
-                     before(TCP_SKB_CB(skb)->seq, start) ||
-                     (skb->next != tail &&
-                      TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb->next)->seq)))
+                     before(TCP_SKB_CB(skb)->seq, start))) {
+                        end_of_skbs = false;
                         break;
+                }
+
+                if (!skb_queue_is_last(list, skb)) {
+                        struct sk_buff *next = skb_queue_next(list, skb);
+                        if (next != tail &&
+                            TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(next)->seq) {
+                                end_of_skbs = false;
+                                break;
+                        }
+                }
 
                 /* Decided to skip this, advance start seq. */
                 start = TCP_SKB_CB(skb)->end_seq;
-                skb = skb->next;
         }
-        if (skb == tail || tcp_hdr(skb)->syn || tcp_hdr(skb)->fin)
+        if (end_of_skbs || tcp_hdr(skb)->syn || tcp_hdr(skb)->fin)
                 return;
 
         while (before(start, end)) {
@@ -4583,7 +4625,8 @@ tcp_collapse(struct sock *sk, struct sk_buff_head *list,
                         }
                         if (!before(start, TCP_SKB_CB(skb)->end_seq)) {
                                 skb = tcp_collapse_one(sk, skb, list);
-                                if (skb == tail ||
+                                if (!skb ||
+                                    skb == tail ||
                                     tcp_hdr(skb)->syn ||
                                     tcp_hdr(skb)->fin)
                                         return;
@@ -4610,17 +4653,21 @@ static void tcp_collapse_ofo_queue(struct sock *sk)
         head = skb;
 
         for (;;) {
-                skb = skb->next;
+                struct sk_buff *next = NULL;
+
+                if (!skb_queue_is_last(&tp->out_of_order_queue, skb))
+                        next = skb_queue_next(&tp->out_of_order_queue, skb);
+                skb = next;
 
                 /* Segment is terminated when we see gap or when
                  * we are at the end of all the queue. */
-                if (skb == (struct sk_buff *)&tp->out_of_order_queue ||
+                if (!skb ||
                     after(TCP_SKB_CB(skb)->seq, end) ||
                     before(TCP_SKB_CB(skb)->end_seq, start)) {
                         tcp_collapse(sk, &tp->out_of_order_queue,
                                      head, skb, start, end);
                         head = skb;
-                        if (skb == (struct sk_buff *)&tp->out_of_order_queue)
+                        if (!skb)
                                 break;
                         /* Start new segment */
                         start = TCP_SKB_CB(skb)->seq;
@@ -4681,10 +4728,11 @@ static int tcp_prune_queue(struct sock *sk)
                 tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U * tp->advmss);
 
         tcp_collapse_ofo_queue(sk);
-        tcp_collapse(sk, &sk->sk_receive_queue,
-                     sk->sk_receive_queue.next,
-                     (struct sk_buff *)&sk->sk_receive_queue,
-                     tp->copied_seq, tp->rcv_nxt);
+        if (!skb_queue_empty(&sk->sk_receive_queue))
+                tcp_collapse(sk, &sk->sk_receive_queue,
+                             skb_peek(&sk->sk_receive_queue),
+                             NULL,
+                             tp->copied_seq, tp->rcv_nxt);
         sk_mem_reclaim(sk);
 
         if (atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf)