Due to slab poisoning after origianl freeing, skb->users will not allow
subsequent freeing to succeed and fire slab debugging, which ends up
with obscure bugs.
Patch based on Eric Sesterhenn's <[EMAIL PROTECTED]> one, I changed
check to skb>truesize instead of skb->users.counter, since the latter in
theory can be different than simple integer containing structure.
--- linux/net/core/skbuff.c.orig 2007-02-28 11:34:13.865540564 +0100
+++ linux/net/core/skbuff.c 2007-03-01 13:42:05.633136591 +0100
@@ -407,6 +407,11 @@ void kfree_skb(struct sk_buff *skb)
{
if (unlikely(!skb))
return;
+#ifdef CONFIG_DEBUG_SLAB
+ /* check for double kfree_skb() */
+ WARN_ON(unlikely((skb->truesize & 0xFFFFFFFF) == 0x6b6b6b6b));
+#endif
+
if (likely(atomic_read(&skb->users) == 1))
smp_rmb();
else if (likely(!atomic_dec_and_test(&skb->users)))
--
Evgeniy Polyakov
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