net: add debugging checks in skb_attempt_defer_free()

edumazet · davem330 · commit e8e1ce8454c9 · 2023-04-23T13:35:07.000+01:00
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
@@ -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)

Original file line number	Diff line number	Diff line change
`@@ -6881,6 +6881,9 @@ nodefer: __kfree_skb(skb);`
`6881`	`6881`	`return;`
`6882`	`6882`	`}`
`6883`	`6883`
	`6884`	`+ DEBUG_NET_WARN_ON_ONCE(skb_dst(skb));`
	`6885`	`+ DEBUG_NET_WARN_ON_ONCE(skb->destructor);`
	`6886`	`+`
`6884`	`6887`	`sd = &per_cpu(softnet_data, cpu);`
`6885`	`6888`	`defer_max = READ_ONCE(sysctl_skb_defer_max);`
`6886`	`6889`	`if (READ_ONCE(sd->defer_count) >= defer_max)`