netdev - [PATCH net-next 2/3] virtio_net: avoid data-races on dev->stats fields

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Message-ID: <20230819044059.833749-3-edumazet@google.com>
Date: Sat, 19 Aug 2023 04:40:58 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: "Michael S . Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>, 
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>, syzbot <syzkaller@...glegroups.com>
Subject: [PATCH net-next 2/3] virtio_net: avoid data-races on dev->stats fields

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

Reported-by: syzbot <syzkaller@...glegroups.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: "Michael S. Tsirkin" <mst@...hat.com>
Cc: Jason Wang <jasowang@...hat.com>
Cc: Xuan Zhuo <xuanzhuo@...ux.alibaba.com>
---
 drivers/net/virtio_net.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 494242bb9cf60cfd54381f12eef338711a558483..d0570de1b0b47ee585ff8945a438e7cd2e1a7de5 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1085,7 +1085,7 @@ static struct sk_buff *receive_small(struct net_device *dev,
 	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;
 	}
 
@@ -1150,7 +1150,7 @@ static void mergeable_buf_free(struct receive_queue *rq, int num_buf,
 		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;
@@ -1259,7 +1259,7 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
 			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);
 			goto err;
 		}
 
@@ -1278,7 +1278,7 @@ static int virtnet_build_xdp_buff_mrg(struct net_device *dev,
 			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);
 			goto err;
 		}
 
@@ -1457,7 +1457,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 	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;
 	}
 
@@ -1489,7 +1489,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 				 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;
 		}
 
@@ -1503,7 +1503,7 @@ static struct sk_buff *receive_mergeable(struct net_device *dev,
 		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;
 		}
 
@@ -1590,7 +1590,7 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
 
 	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;
 	}
@@ -1630,7 +1630,7 @@ static void receive_buf(struct virtnet_info *vi, struct receive_queue *rq,
 	return;
 
 frame_err:
-	dev->stats.rx_frame_errors++;
+	DEV_STATS_INC(dev, rx_frame_errors);
 	dev_kfree_skb(skb);
 }
 
@@ -2170,12 +2170,12 @@ static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
 
 	/* 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;
 	}
@@ -2394,10 +2394,10 @@ static void virtnet_stats(struct net_device *dev,
 		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)
-- 
2.42.0.rc1.204.g551eb34607-goog