tcp: provide more information on the tcp receive_queue bugs

The addition of rcv_nxt allows to discern whether the skb
was out of place or tp->copied. Also catch fancy combination
of flags if necessary (sadly we might miss the actual causer
flags as it might have already returned).

Btw, we perhaps would want to forward copied_seq in
somewhere or otherwise we might have some nice loop with
WARN stuff within but where to do that safely I don't
know at this stage until more is known (but it is not
made significantly worse by this patch).

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 98440ad82558064ce4eb7ee9ad525f9725413739..f1813bc7108811a50ff8284775ad053623903a2e 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -1183,7 +1183,9 @@ void tcp_cleanup_rbuf(struct sock *sk, int copied)
 #if TCP_DEBUG
        struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
 
-       WARN_ON(skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq));
+       WARN(skb && !before(tp->copied_seq, TCP_SKB_CB(skb)->end_seq),
+            KERN_INFO "cleanup rbuf bug: copied %X seq %X rcvnxt %X\n",
+            tp->copied_seq, TCP_SKB_CB(skb)->end_seq, tp->rcv_nxt);
 #endif
 
        if (inet_csk_ack_scheduled(sk)) {
@@ -1430,11 +1432,13 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                        /* Now that we have two receive queues this
                         * shouldn't happen.
                         */
-                       if (before(*seq, TCP_SKB_CB(skb)->seq)) {
-                               printk(KERN_INFO "recvmsg bug: copied %X "
-                                      "seq %X\n", *seq, TCP_SKB_CB(skb)->seq);
+                       if (WARN(before(*seq, TCP_SKB_CB(skb)->seq),
+                            KERN_INFO "recvmsg bug: copied %X "
+                                      "seq %X rcvnxt %X fl %X\n", *seq,
+                                      TCP_SKB_CB(skb)->seq, tp->rcv_nxt,
+                                      flags))
                                break;
-                       }
+
                        offset = *seq - TCP_SKB_CB(skb)->seq;
                        if (tcp_hdr(skb)->syn)
                                offset--;
@@ -1443,8 +1447,9 @@ int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
                        if (tcp_hdr(skb)->fin)
                                goto found_fin_ok;
                        WARN(!(flags & MSG_PEEK), KERN_INFO "recvmsg bug 2: "
-                                       "copied %X seq %X\n", *seq,
-                                       TCP_SKB_CB(skb)->seq);
+                                       "copied %X seq %X rcvnxt %X fl %X\n",
+                                       *seq, TCP_SKB_CB(skb)->seq,
+                                       tp->rcv_nxt, flags);
                }
 
                /* Well, if we have backlog, try to process it now yet. */