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authorEric Dumazet <edumazet@google.com>2012-06-05 22:35:24 +0000
committerDavid S. Miller <davem@davemloft.net>2012-06-10 20:23:20 -0700
commit83a27052c3376793bc879e00e6e6805d6fb7aab9 (patch)
tree5ee6d28233be328ac9f14ad0f0aa674a498b28d2
parent7dbb491878a2c51d372a8890fa45a8ff80358af1 (diff)
virtio-net: fix a race on 32bit arches
commit 3fa2a1df909 (virtio-net: per cpu 64 bit stats (v2)) added a race on 32bit arches. We must use separate syncp for rx and tx path as they can be run at the same time on different cpus. Thus one sequence increment can be lost and readers spin forever. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Stephen Hemminger <shemminger@vyatta.com> Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Jason Wang <jasowang@redhat.com> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--drivers/net/virtio_net.c19
1 files changed, 12 insertions, 7 deletions
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 5214b1eceb95..f18149ae2588 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -42,7 +42,8 @@ module_param(gso, bool, 0444);
#define VIRTNET_DRIVER_VERSION "1.0.0"
struct virtnet_stats {
- struct u64_stats_sync syncp;
+ struct u64_stats_sync tx_syncp;
+ struct u64_stats_sync rx_syncp;
u64 tx_bytes;
u64 tx_packets;
@@ -300,10 +301,10 @@ static void receive_buf(struct net_device *dev, void *buf, unsigned int len)
hdr = skb_vnet_hdr(skb);
- u64_stats_update_begin(&stats->syncp);
+ u64_stats_update_begin(&stats->rx_syncp);
stats->rx_bytes += skb->len;
stats->rx_packets++;
- u64_stats_update_end(&stats->syncp);
+ u64_stats_update_end(&stats->rx_syncp);
if (hdr->hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
pr_debug("Needs csum!\n");
@@ -565,10 +566,10 @@ static unsigned int free_old_xmit_skbs(struct virtnet_info *vi)
while ((skb = virtqueue_get_buf(vi->svq, &len)) != NULL) {
pr_debug("Sent skb %p\n", skb);
- u64_stats_update_begin(&stats->syncp);
+ u64_stats_update_begin(&stats->tx_syncp);
stats->tx_bytes += skb->len;
stats->tx_packets++;
- u64_stats_update_end(&stats->syncp);
+ u64_stats_update_end(&stats->tx_syncp);
tot_sgs += skb_vnet_hdr(skb)->num_sg;
dev_kfree_skb_any(skb);
@@ -703,12 +704,16 @@ static struct rtnl_link_stats64 *virtnet_stats(struct net_device *dev,
u64 tpackets, tbytes, rpackets, rbytes;
do {
- start = u64_stats_fetch_begin(&stats->syncp);
+ start = u64_stats_fetch_begin(&stats->tx_syncp);
tpackets = stats->tx_packets;
tbytes = stats->tx_bytes;
+ } while (u64_stats_fetch_retry(&stats->tx_syncp, start));
+
+ do {
+ start = u64_stats_fetch_begin(&stats->rx_syncp);
rpackets = stats->rx_packets;
rbytes = stats->rx_bytes;
- } while (u64_stats_fetch_retry(&stats->syncp, start));
+ } while (u64_stats_fetch_retry(&stats->rx_syncp, start));
tot->rx_packets += rpackets;
tot->tx_packets += tpackets;