From: Eric Dumazet <edumazet@google.com>
Date: Thu, 21 Sep 2023 08:52:17 +0000
Subject: virtio_net: avoid data-races on dev->stats fields
Git-commit: d12a26b74fb77434b73fe39022266c4b00907219
Patch-mainline: v6.7-rc1
References: git-fixes

Use DEV_STATS_INC() and DEV_STATS_READ() which provide
atomicity on paths that can be used concurrently.

Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Dario Faggioli <dfaggioli@suse.com>
---
 drivers/net/virtio_net.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -892,7 +892,7 @@
 	if (unlikely(len > GOOD_PACKET_LEN)) {
 		pr_debug("%s: rx error: len %u exceeds max size %d\n",
 			 dev->name, len, GOOD_PACKET_LEN);
-		dev->stats.rx_length_errors++;
+		DEV_STATS_INC(dev, rx_length_errors);
 		goto err;
 	}
 
@@ -1132,7 +1132,7 @@
 			pr_debug("%s: rx error: %d buffers out of %d missing\n",
 				 dev->name, *num_buf,
 				 virtio16_to_cpu(vi->vdev, hdr->num_buffers));
-			dev->stats.rx_length_errors++;
+			DEV_STATS_INC(dev, rx_length_errors);
 			return -EINVAL;
 		}
 
@@ -1151,7 +1151,7 @@
 			put_page(page);
 			pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
 				 dev->name, len, (unsigned long)(truesize - room));
-			dev->stats.rx_length_errors++;
+			DEV_STATS_INC(dev, rx_length_errors);
 			return -EINVAL;
 		}
 
@@ -1195,7 +1195,7 @@
 	if (unlikely(len > truesize - room)) {
 		pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
 			 dev->name, len, (unsigned long)(truesize - room));
-		dev->stats.rx_length_errors++;
+		DEV_STATS_INC(dev, rx_length_errors);
 		goto err_skb;
 	}
 
@@ -1356,7 +1356,7 @@
 				 dev->name, num_buf,
 				 virtio16_to_cpu(vi->vdev,
 						 hdr->num_buffers));
-			dev->stats.rx_length_errors++;
+			DEV_STATS_INC(dev, rx_length_errors);
 			goto err_buf;
 		}
 
@@ -1370,7 +1370,7 @@
 		if (unlikely(len > truesize - room)) {
 			pr_debug("%s: rx error: len %u exceeds truesize %lu\n",
 				 dev->name, len, (unsigned long)(truesize - room));
-			dev->stats.rx_length_errors++;
+			DEV_STATS_INC(dev, rx_length_errors);
 			goto err_skb;
 		}
 
@@ -1417,7 +1417,7 @@
 		if (unlikely(!buf)) {
 			pr_debug("%s: rx error: %d buffers missing\n",
 				 dev->name, num_buf);
-			dev->stats.rx_length_errors++;
+			DEV_STATS_INC(dev, rx_length_errors);
 			break;
 		}
 		stats->bytes += len;
@@ -1471,7 +1471,7 @@
 
 	if (unlikely(len < vi->hdr_len + ETH_HLEN)) {
 		pr_debug("%s: short packet %i\n", dev->name, len);
-		dev->stats.rx_length_errors++;
+		DEV_STATS_INC(dev, rx_length_errors);
 		virtnet_rq_free_unused_buf(rq->vq, buf);
 		return;
 	}
@@ -1511,7 +1511,7 @@
 	return;
 
 frame_err:
-	dev->stats.rx_frame_errors++;
+	DEV_STATS_INC(dev, rx_frame_errors);
 	dev_kfree_skb(skb);
 }
 
@@ -2051,12 +2051,12 @@
 
 	/* This should not happen! */
 	if (unlikely(err)) {
-		dev->stats.tx_fifo_errors++;
+		DEV_STATS_INC(dev, tx_fifo_errors);
 		if (net_ratelimit())
 			dev_warn(&dev->dev,
 				 "Unexpected TXQ (%d) queue failure: %d\n",
 				 qnum, err);
-		dev->stats.tx_dropped++;
+		DEV_STATS_INC(dev, tx_dropped);
 		dev_kfree_skb_any(skb);
 		return NETDEV_TX_OK;
 	}
@@ -2275,10 +2275,10 @@
 		tot->tx_errors  += terrors;
 	}
 
-	tot->tx_dropped = dev->stats.tx_dropped;
-	tot->tx_fifo_errors = dev->stats.tx_fifo_errors;
-	tot->rx_length_errors = dev->stats.rx_length_errors;
-	tot->rx_frame_errors = dev->stats.rx_frame_errors;
+	tot->tx_dropped = DEV_STATS_READ(dev, tx_dropped);
+	tot->tx_fifo_errors = DEV_STATS_READ(dev, tx_fifo_errors);
+	tot->rx_length_errors = DEV_STATS_READ(dev, rx_length_errors);
+	tot->rx_frame_errors = DEV_STATS_READ(dev, rx_frame_errors);
 }
 
 static void virtnet_ack_link_announce(struct virtnet_info *vi)
