Re: [PATCH] tcpdump may trace some outbound packets twice.

[Ranjit Manomohan <ranjitm@google.com>]

Thank you for the comments. Incorporated feedback into current version.

-Thanks,
Ranjit

--- linux-2.6/net/sched/sch_generic.c	2006-05-10 12:34:52.000000000 -0700
+++ linux/net/sched/sch_generic.c	2006-05-14 08:53:33.000000000 -0700
@@ -136,8 +136,12 @@
 
 			if (!netif_queue_stopped(dev)) {
 				int ret;
+				struct sk_buff *skbc = NULL;
+				/* Clone the skb so that we hold a reference
+				 * to its data and we can trace it after a
+				 * successful transmit. */
 				if (netdev_nit)
-					dev_queue_xmit_nit(skb, dev);
+					skbc = skb_clone(skb, GFP_ATOMIC);
 
 				ret = dev->hard_start_xmit(skb, dev);
 				if (ret == NETDEV_TX_OK) { 
@@ -145,9 +149,17 @@
 						dev->xmit_lock_owner = -1;
 						spin_unlock(&dev->xmit_lock);
 					}
+					if (skbc) {
+						/* transmit succeeded, 
+						 * trace the clone. */
+						dev_queue_xmit_nit(skbc,dev);
+						kfree_skb(skbc);
+					}
 					spin_lock(&dev->queue_lock);
 					return -1;
 				}
+				/* Free clone if it exists */
+				kfree_skb(skbc);
 				if (ret == NETDEV_TX_LOCKED && nolock) {
 					spin_lock(&dev->queue_lock);
 					goto collision;