Merge branch 'net-few-debug-refinements'

Eric Dumazet says:

====================
net: few debug refinements

Adopt DEBUG_NET_WARN_ON_ONCE() or WARN_ON_ONCE()
in some places where it makes sense.

Add checks in napi_consume_skb() and __napi_alloc_skb()

Make sure napi_get_frags() does not use page fragments
for skb->head.
====================

Link: https://lore.kernel.org/r/20220608160438.1342569-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/core/dev.c

@@ -3925,7 +3925,7 @@ int dev_loopback_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
 	skb->pkt_type = PACKET_LOOPBACK;
 	if (skb->ip_summed == CHECKSUM_NONE)
 		skb->ip_summed = CHECKSUM_UNNECESSARY;
-	WARN_ON(!skb_dst(skb));
+	DEBUG_NET_WARN_ON_ONCE(!skb_dst(skb));
 	skb_dst_force(skb);
 	netif_rx(skb);
 	return 0;
@@ -6351,6 +6351,23 @@ int dev_set_threaded(struct net_device *dev, bool threaded)
 }
 EXPORT_SYMBOL(dev_set_threaded);
 
+/* Double check that napi_get_frags() allocates skbs with
+ * skb->head being backed by slab, not a page fragment.
+ * This is to make sure bug fixed in 3226b158e67c
+ * ("net: avoid 32 x truesize under-estimation for tiny skbs")
+ * does not accidentally come back.
+ */
+static void napi_get_frags_check(struct napi_struct *napi)
+{
+	struct sk_buff *skb;
+
+	local_bh_disable();
+	skb = napi_get_frags(napi);
+	WARN_ON_ONCE(skb && skb->head_frag);
+	napi_free_frags(napi);
+	local_bh_enable();
+}
+
 void netif_napi_add_weight(struct net_device *dev, struct napi_struct *napi,
 			   int (*poll)(struct napi_struct *, int), int weight)
 {
@@ -6378,6 +6395,7 @@ void netif_napi_add_weight(struct net_device *dev, struct napi_struct *napi,
 	set_bit(NAPI_STATE_NPSVC, &napi->state);
 	list_add_rcu(&napi->dev_list, &dev->napi_list);
 	napi_hash_add(napi);
+	napi_get_frags_check(napi);
 	/* Create kthread for this napi if dev->threaded is set.
 	 * Clear dev->threaded if kthread creation failed so that
 	 * threaded mode will not be enabled in napi_enable().

net/core/skbuff.c

@@ -560,6 +560,7 @@ struct sk_buff *__napi_alloc_skb(struct napi_struct *napi, unsigned int len,
 	struct sk_buff *skb;
 	void *data;
 
+	DEBUG_NET_WARN_ON_ONCE(!in_softirq());
 	len += NET_SKB_PAD + NET_IP_ALIGN;
 
 	/* If requested length is either too small or too big,
@@ -728,7 +729,7 @@ void skb_release_head_state(struct sk_buff *skb)
 {
 	skb_dst_drop(skb);
 	if (skb->destructor) {
-		WARN_ON(in_hardirq());
+		DEBUG_NET_WARN_ON_ONCE(in_hardirq());
 		skb->destructor(skb);
 	}
 #if IS_ENABLED(CONFIG_NF_CONNTRACK)
@@ -981,7 +982,7 @@ void napi_consume_skb(struct sk_buff *skb, int budget)
 		return;
 	}
 
-	lockdep_assert_in_softirq();
+	DEBUG_NET_WARN_ON_ONCE(!in_softirq());
 
 	if (!skb_unref(skb))
 		return;

net/core/sock.c

@@ -2844,7 +2844,7 @@ void __release_sock(struct sock *sk)
 		do {
 			next = skb->next;
 			prefetch(next);
-			WARN_ON_ONCE(skb_dst_is_noref(skb));
+			DEBUG_NET_WARN_ON_ONCE(skb_dst_is_noref(skb));
 			skb_mark_not_on_list(skb);
 			sk_backlog_rcv(sk, skb);
 

net/core/stream.c

@@ -196,13 +196,13 @@ void sk_stream_kill_queues(struct sock *sk)
 	__skb_queue_purge(&sk->sk_receive_queue);
 
 	/* Next, the write queue. */
-	WARN_ON(!skb_queue_empty(&sk->sk_write_queue));
+	WARN_ON_ONCE(!skb_queue_empty(&sk->sk_write_queue));
 
 	/* Account for returned memory. */
 	sk_mem_reclaim_final(sk);
 
-	WARN_ON(sk->sk_wmem_queued);
-	WARN_ON(sk->sk_forward_alloc);
+	WARN_ON_ONCE(sk->sk_wmem_queued);
+	WARN_ON_ONCE(sk->sk_forward_alloc);
 
 	/* It is _impossible_ for the backlog to contain anything
 	 * when we get here.  All user references to this socket

net/ipv4/af_inet.c

@@ -148,10 +148,10 @@ void inet_sock_destruct(struct sock *sk)
 		return;
 	}
 
-	WARN_ON(atomic_read(&sk->sk_rmem_alloc));
-	WARN_ON(refcount_read(&sk->sk_wmem_alloc));
-	WARN_ON(sk->sk_wmem_queued);
-	WARN_ON(sk_forward_alloc_get(sk));
+	WARN_ON_ONCE(atomic_read(&sk->sk_rmem_alloc));
+	WARN_ON_ONCE(refcount_read(&sk->sk_wmem_alloc));
+	WARN_ON_ONCE(sk->sk_wmem_queued);
+	WARN_ON_ONCE(sk_forward_alloc_get(sk));
 
 	kfree(rcu_dereference_protected(inet->inet_opt, 1));
 	dst_release(rcu_dereference_protected(sk->sk_dst_cache, 1));

net/unix/af_unix.c

@@ -302,7 +302,7 @@ static void __unix_remove_socket(struct sock *sk)
 
 static void __unix_insert_socket(struct sock *sk)
 {
-	WARN_ON(!sk_unhashed(sk));
+	DEBUG_NET_WARN_ON_ONCE(!sk_unhashed(sk));
 	sk_add_node(sk, &unix_socket_table[sk->sk_hash]);
 }
 
@@ -554,9 +554,9 @@ static void unix_sock_destructor(struct sock *sk)
 		u->oob_skb = NULL;
 	}
 #endif
-	WARN_ON(refcount_read(&sk->sk_wmem_alloc));
-	WARN_ON(!sk_unhashed(sk));
-	WARN_ON(sk->sk_socket);
+	DEBUG_NET_WARN_ON_ONCE(refcount_read(&sk->sk_wmem_alloc));
+	DEBUG_NET_WARN_ON_ONCE(!sk_unhashed(sk));
+	DEBUG_NET_WARN_ON_ONCE(sk->sk_socket);
 	if (!sock_flag(sk, SOCK_DEAD)) {
 		pr_info("Attempt to release alive unix socket: %p\n", sk);
 		return;