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++) {