hv_netvsc: use per_cpu stats to calculate TX/RX data

Current code does not lock anything when calculating the TX and RX stats.
As a result, the RX and TX data reported by ifconfig are not accuracy in a
system with high network throughput and multiple CPUs (in my test,
RX/TX = 83% between 2 HyperV VM nodes which have 8 vCPUs and 40G Ethernet).

This patch fixed the above issue by using per_cpu stats.
netvsc_get_stats64() summarizes TX and RX data by iterating over all CPUs
to get their respective stats.

This v2 patch addressed David's comments on the cleanup path when
netdev_alloc_pcpu_stats() failed.

Signed-off-by: Simon Xiao <sixiao@microsoft.com>
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 41071d32bc8e..5a92b36daed6 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -611,6 +611,12 @@ struct multi_send_data {
 	u32 count; /* counter of batched packets */
 };
 
+struct netvsc_stats {
+	u64 packets;
+	u64 bytes;
+	struct u64_stats_sync s_sync;
+};
+
 /* The context of the netvsc device  */
 struct net_device_context {
 	/* point back to our device context */
@@ -618,6 +624,9 @@ struct net_device_context {
 	struct delayed_work dwork;
 	struct work_struct work;
 	u32 msg_enable; /* debug level */
+
+	struct netvsc_stats __percpu *tx_stats;
+	struct netvsc_stats __percpu *rx_stats;
 };
 
 /* Per netvsc device */