[TCP]: Add code to help track down "BUG at net/ipv4/tcp_output.c:438!"

This is the second report of this bug.  Unfortunately the first
reporter hasn't been able to reproduce it since to provide more
debugging info.

So let's apply this patch for 2.6.14 to

1) Make this non-fatal.
2) Provide the info we need to track it down.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 1 deletions

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 8225e4257258..f37a50e55b68 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -435,7 +435,14 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, unsigned int mss
         int nsize, old_factor;
         u16 flags;
 
-        BUG_ON(len >= skb->len);
+        if (unlikely(len >= skb->len)) {
+                printk(KERN_DEBUG "TCP: seg_size=%u, mss=%u, seq=%u, "
+                       "end_seq=%u, skb->len=%u.\n", len, mss_now,
+                       TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq,
+                       skb->len);
+                WARN_ON(1);
+                return 0;
+        }
 
         nsize = skb_headlen(skb) - len;
         if (nsize < 0)