ixgbe: fix stats handling

Current ixgbe stats have following problems :

- Not 64 bit safe (on 32bit arches)

- Not safe in ixgbe_clean_rx_irq() :
   All cpus dirty a common location (netdev->stats.rx_bytes &
netdev->stats.rx_packets) without proper synchronization.
   This slow down a bit multiqueue operations, and possibly miss some
updates.

Fixes :

Implement ndo_get_stats64() method to provide accurate 64bit rx|tx
bytes/packets counters, using 64bit safe infrastructure.

ixgbe_get_ethtool_stats() also use this infrastructure to provide 64bit
safe counters.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Don Skidmore <donald.c.skidmore@intel.com>
Tested-by: Stephen Ko <stephen.s.ko@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 17 insertions, 12 deletions

diff --git a/drivers/net/ixgbe/ixgbe_ethtool.c b/drivers/net/ixgbe/ixgbe_ethtool.c
index dbfd62fd40e..3dc731c22ff 100644
--- a/drivers/net/ixgbe/ixgbe_ethtool.c
+++ b/drivers/net/ixgbe/ixgbe_ethtool.c
@@ -999,12 +999,11 @@ static void ixgbe_get_ethtool_stats(struct net_device *netdev,
                                     struct ethtool_stats *stats, u64 *data)
 {
 	struct ixgbe_adapter *adapter = netdev_priv(netdev);
-	u64 *queue_stat;
-	int stat_count = sizeof(struct ixgbe_queue_stats) / sizeof(u64);
 	struct rtnl_link_stats64 temp;
 	const struct rtnl_link_stats64 *net_stats;
-	int j, k;
-	int i;
+	unsigned int start;
+	struct ixgbe_ring *ring;
+	int i, j;
 	char *p = NULL;
 
 	ixgbe_update_stats(adapter);
@@ -1025,16 +1024,22 @@ static void ixgbe_get_ethtool_stats(struct net_device *netdev,
 		           sizeof(u64)) ? *(u64 *)p : *(u32 *)p;
 	}
 	for (j = 0; j < adapter->num_tx_queues; j++) {
-		queue_stat = (u64 *)&adapter->tx_ring[j]->stats;
-		for (k = 0; k < stat_count; k++)
-			data[i + k] = queue_stat[k];
-		i += k;
+		ring = adapter->tx_ring[j];
+		do {
+			start = u64_stats_fetch_begin_bh(&ring->syncp);
+			data[i]   = ring->stats.packets;
+			data[i+1] = ring->stats.bytes;
+		} while (u64_stats_fetch_retry_bh(&ring->syncp, start));
+		i += 2;
 	}
 	for (j = 0; j < adapter->num_rx_queues; j++) {
-		queue_stat = (u64 *)&adapter->rx_ring[j]->stats;
-		for (k = 0; k < stat_count; k++)
-			data[i + k] = queue_stat[k];
-		i += k;
+		ring = adapter->rx_ring[j];
+		do {
+			start = u64_stats_fetch_begin_bh(&ring->syncp);
+			data[i]   = ring->stats.packets;
+			data[i+1] = ring->stats.bytes;
+		} while (u64_stats_fetch_retry_bh(&ring->syncp, start));
+		i += 2;
 	}
 	if (adapter->flags & IXGBE_FLAG_DCB_ENABLED) {
 		for (j = 0; j < MAX_TX_PACKET_BUFFERS; j++) {