net: add debugging checks in skb_attempt_defer_free()

Make sure skbs that are stored in softnet_data.defer_list
do not have a dst attached.

Also make sure the the skb was orphaned.

Link: https://lore.kernel.org/netdev/CANn89iJuEVe72bPmEftyEJHLzzN=QNR2yueFjTxYXCEpS5S8HQ@mail.gmail.com/T/
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 0d99880..bd815a0 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -6881,6 +6881,9 @@ nodefer:  __kfree_skb(skb);
                return;
        }
 
+       DEBUG_NET_WARN_ON_ONCE(skb_dst(skb));
+       DEBUG_NET_WARN_ON_ONCE(skb->destructor);
+
        sd = &per_cpu(softnet_data, cpu);
        defer_max = READ_ONCE(sysctl_skb_defer_max);
        if (READ_ONCE(sd->defer_count) >= defer_max)