1 files changed, 20 insertions, 9 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 14bc654b6842..1d58ce829dca 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -388,7 +388,7 @@ static int compute_score(struct sock *sk, struct net *net,
                 return -1;
         score += 4;
 
-        if (sk->sk_incoming_cpu == raw_smp_processor_id())
+        if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
                 score++;
         return score;
 }
@@ -1316,6 +1316,20 @@ static void udp_set_dev_scratch(struct sk_buff *skb)
                 scratch->_tsize_state |= UDP_SKB_IS_STATELESS;
 }
 
+static void udp_skb_csum_unnecessary_set(struct sk_buff *skb)
+{
+        /* We come here after udp_lib_checksum_complete() returned 0.
+         * This means that __skb_checksum_complete() might have
+         * set skb->csum_valid to 1.
+         * On 64bit platforms, we can set csum_unnecessary
+         * to true, but only if the skb is not shared.
+         */
+#if BITS_PER_LONG == 64
+        if (!skb_shared(skb))
+                udp_skb_scratch(skb)->csum_unnecessary = true;
+#endif
+}
+
 static int udp_skb_truesize(struct sk_buff *skb)
 {
         return udp_skb_scratch(skb)->_tsize_state & ~UDP_SKB_IS_STATELESS;
@@ -1550,10 +1564,7 @@ static struct sk_buff *__first_packet_length(struct sock *sk,
                         *total += skb->truesize;
                         kfree_skb(skb);
                 } else {
-                        /* the csum related bits could be changed, refresh
-                         * the scratch area
-                         */
-                        udp_set_dev_scratch(skb);
+                        udp_skb_csum_unnecessary_set(skb);
                         break;
                 }
         }
@@ -1577,7 +1588,7 @@ static int first_packet_length(struct sock *sk)
 
         spin_lock_bh(&rcvq->lock);
         skb = __first_packet_length(sk, rcvq, &total);
-        if (!skb && !skb_queue_empty(sk_queue)) {
+        if (!skb && !skb_queue_empty_lockless(sk_queue)) {
                 spin_lock(&sk_queue->lock);
                 skb_queue_splice_tail_init(sk_queue, rcvq);
                 spin_unlock(&sk_queue->lock);
@@ -1650,7 +1661,7 @@ struct sk_buff *__skb_recv_udp(struct sock *sk, unsigned int flags,
                                 return skb;
                         }
 
-                        if (skb_queue_empty(sk_queue)) {
+                        if (skb_queue_empty_lockless(sk_queue)) {
                                 spin_unlock_bh(&queue->lock);
                                 goto busy_check;
                         }
@@ -1676,7 +1687,7 @@ busy_check:
                                 break;
 
                         sk_busy_loop(sk, flags & MSG_DONTWAIT);
-                } while (!skb_queue_empty(sk_queue));
+                } while (!skb_queue_empty_lockless(sk_queue));
 
                 /* sk_queue is empty, reader_queue may contain peeked packets */
         } while (timeo &&
@@ -2712,7 +2723,7 @@ __poll_t udp_poll(struct file *file, struct socket *sock, poll_table *wait)
         __poll_t mask = datagram_poll(file, sock, wait);
         struct sock *sk = sock->sk;
 
-        if (!skb_queue_empty(&udp_sk(sk)->reader_queue))
+        if (!skb_queue_empty_lockless(&udp_sk(sk)->reader_queue))
                 mask |= EPOLLIN | EPOLLRDNORM;
 
         /* Check for false positives due to checksum errors */