net_sched: always clone skbs

Pawel reported a panic related to handling shared skbs in ixgbe
incorrectly. So we need to revert my previous patch to work around
this bug. Instead of reverting the patch completely, I just revert
the essential lines, so we can add the previous optimization
back more easily in future.

    commit 3511c913
    Author: Changli Gao <xiaosuo@gmail.com>
    Date:   Sat Oct 16 13:04:08 2010 +0000

        net_sched: remove the unused parameter of qdisc_create_dflt()
Reported-by: Pawel Staszewski <pstaszewski@itcare.pl>
Signed-off-by: Changli Gao <xiaosuo@gmail.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sch_generic.h

@@ -610,11 +610,7 @@ static inline struct sk_buff *skb_act_clone(struct sk_buff *skb, gfp_t gfp_mask,
 {
 	struct sk_buff *n;
 
-	if ((action == TC_ACT_STOLEN || action == TC_ACT_QUEUED) &&
-	    !skb_shared(skb))
-		n = skb_get(skb);
-	else
-		n = skb_clone(skb, gfp_mask);
+	n = skb_clone(skb, gfp_mask);
 
 	if (n) {
 		n->tc_verd = SET_TC_VERD(n->tc_verd, 0);