i40e: Add support for 64 bit netstats

This change brings support for 64 bit netstats to the driver. Previously
the stats were 64 bit but highly racy due to the fact that 64 bit
transactions are not atomic on 32 bit systems.  This change makes is so
that the 64 bit byte and packet stats are reliable on all architectures.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/i40e/i40e_ethtool.c

@@ -579,6 +579,7 @@ static void i40e_get_ethtool_stats(struct net_device *netdev,
 	char *p;
 	int j;
 	struct rtnl_link_stats64 *net_stats = i40e_get_vsi_stats_struct(vsi);
+	unsigned int start;
 
 	i40e_update_stats(vsi);
 
@@ -587,12 +588,30 @@ static void i40e_get_ethtool_stats(struct net_device *netdev,
 		data[i++] = (i40e_gstrings_net_stats[j].sizeof_stat ==
 			sizeof(u64)) ? *(u64 *)p : *(u32 *)p;
 	}
+	rcu_read_lock();
 	for (j = 0; j < vsi->num_queue_pairs; j++, i += 4) {
-		data[i] = vsi->tx_rings[j]->stats.packets;
-		data[i + 1] = vsi->tx_rings[j]->stats.bytes;
-		data[i + 2] = vsi->rx_rings[j]->stats.packets;
-		data[i + 3] = vsi->rx_rings[j]->stats.bytes;
+		struct i40e_ring *tx_ring = ACCESS_ONCE(vsi->tx_rings[j]);
+		struct i40e_ring *rx_ring;
+
+		if (!tx_ring)
+			continue;
+
+		/* process Tx ring statistics */
+		do {
+			start = u64_stats_fetch_begin_bh(&tx_ring->syncp);
+			data[i] = tx_ring->stats.packets;
+			data[i + 1] = tx_ring->stats.bytes;
+		} while (u64_stats_fetch_retry_bh(&tx_ring->syncp, start));
+
+		/* Rx ring is the 2nd half of the queue pair */
+		rx_ring = &tx_ring[1];
+		do {
+			start = u64_stats_fetch_begin_bh(&rx_ring->syncp);
+			data[i + 2] = rx_ring->stats.packets;
+			data[i + 3] = rx_ring->stats.bytes;
+		} while (u64_stats_fetch_retry_bh(&rx_ring->syncp, start));
 	}
+	rcu_read_unlock();
 	if (vsi == pf->vsi[pf->lan_vsi]) {
 		for (j = 0; j < I40E_GLOBAL_STATS_LEN; j++) {
 			p = (char *)pf + i40e_gstrings_stats[j].stat_offset;

drivers/net/ethernet/intel/i40e/i40e_main.c

@@ -347,14 +347,53 @@ struct rtnl_link_stats64 *i40e_get_vsi_stats_struct(struct i40e_vsi *vsi)
  **/
 static struct rtnl_link_stats64 *i40e_get_netdev_stats_struct(
 					     struct net_device *netdev,
-					     struct rtnl_link_stats64 *storage)
+					     struct rtnl_link_stats64 *stats)
 {
 	struct i40e_netdev_priv *np = netdev_priv(netdev);
 	struct i40e_vsi *vsi = np->vsi;
+	struct rtnl_link_stats64 *vsi_stats = i40e_get_vsi_stats_struct(vsi);
+	int i;
+
+	rcu_read_lock();
+	for (i = 0; i < vsi->num_queue_pairs; i++) {
+		struct i40e_ring *tx_ring, *rx_ring;
+		u64 bytes, packets;
+		unsigned int start;
+
+		tx_ring = ACCESS_ONCE(vsi->tx_rings[i]);
+		if (!tx_ring)
+			continue;
 
-	*storage = *i40e_get_vsi_stats_struct(vsi);
+		do {
+			start = u64_stats_fetch_begin_bh(&tx_ring->syncp);
+			packets = tx_ring->stats.packets;
+			bytes   = tx_ring->stats.bytes;
+		} while (u64_stats_fetch_retry_bh(&tx_ring->syncp, start));
+
+		stats->tx_packets += packets;
+		stats->tx_bytes   += bytes;
+		rx_ring = &tx_ring[1];
+
+		do {
+			start = u64_stats_fetch_begin_bh(&rx_ring->syncp);
+			packets = rx_ring->stats.packets;
+			bytes   = rx_ring->stats.bytes;
+		} while (u64_stats_fetch_retry_bh(&rx_ring->syncp, start));
 
-	return storage;
+		stats->rx_packets += packets;
+		stats->rx_bytes   += bytes;
+	}
+	rcu_read_unlock();
+
+	/* following stats updated by ixgbe_watchdog_task() */
+	stats->multicast	= vsi_stats->multicast;
+	stats->tx_errors	= vsi_stats->tx_errors;
+	stats->tx_dropped	= vsi_stats->tx_dropped;
+	stats->rx_errors	= vsi_stats->rx_errors;
+	stats->rx_crc_errors	= vsi_stats->rx_crc_errors;
+	stats->rx_length_errors	= vsi_stats->rx_length_errors;
+
+	return stats;
 }
 
 /**
@@ -708,21 +747,38 @@ void i40e_update_stats(struct i40e_vsi *vsi)
 	tx_restart = tx_busy = 0;
 	rx_page = 0;
 	rx_buf = 0;
+	rcu_read_lock();
 	for (q = 0; q < vsi->num_queue_pairs; q++) {
 		struct i40e_ring *p;
+		u64 bytes, packets;
+		unsigned int start;
 
-		p = vsi->rx_rings[q];
-		rx_b += p->stats.bytes;
-		rx_p += p->stats.packets;
-		rx_buf += p->rx_stats.alloc_rx_buff_failed;
-		rx_page += p->rx_stats.alloc_rx_page_failed;
+		/* locate Tx ring */
+		p = ACCESS_ONCE(vsi->tx_rings[q]);
 
-		p = vsi->tx_rings[q];
-		tx_b += p->stats.bytes;
-		tx_p += p->stats.packets;
+		do {
+			start = u64_stats_fetch_begin_bh(&p->syncp);
+			packets = p->stats.packets;
+			bytes = p->stats.bytes;
+		} while (u64_stats_fetch_retry_bh(&p->syncp, start));
+		tx_b += bytes;
+		tx_p += packets;
 		tx_restart += p->tx_stats.restart_queue;
 		tx_busy += p->tx_stats.tx_busy;
+
+		/* Rx queue is part of the same block as Tx queue */
+		p = &p[1];
+		do {
+			start = u64_stats_fetch_begin_bh(&p->syncp);
+			packets = p->stats.packets;
+			bytes = p->stats.bytes;
+		} while (u64_stats_fetch_retry_bh(&p->syncp, start));
+		rx_b += bytes;
+		rx_p += packets;
+		rx_buf += p->rx_stats.alloc_rx_buff_failed;
+		rx_page += p->rx_stats.alloc_rx_page_failed;
 	}
+	rcu_read_unlock();
 	vsi->tx_restart = tx_restart;
 	vsi->tx_busy = tx_busy;
 	vsi->rx_page_failed = rx_page;

drivers/net/ethernet/intel/i40e/i40e_txrx.c

@@ -411,8 +411,10 @@ static bool i40e_clean_tx_irq(struct i40e_ring *tx_ring, int budget)
 
 	i += tx_ring->count;
 	tx_ring->next_to_clean = i;
+	u64_stats_update_begin(&tx_ring->syncp);
 	tx_ring->stats.bytes += total_bytes;
 	tx_ring->stats.packets += total_packets;
+	u64_stats_update_end(&tx_ring->syncp);
 	tx_ring->q_vector->tx.total_bytes += total_bytes;
 	tx_ring->q_vector->tx.total_packets += total_packets;
 
@@ -1075,8 +1077,10 @@ next_desc:
 	}
 
 	rx_ring->next_to_clean = i;
+	u64_stats_update_begin(&rx_ring->syncp);
 	rx_ring->stats.packets += total_rx_packets;
 	rx_ring->stats.bytes += total_rx_bytes;
+	u64_stats_update_end(&rx_ring->syncp);
 	rx_ring->q_vector->rx.total_packets += total_rx_packets;
 	rx_ring->q_vector->rx.total_bytes += total_rx_bytes;
 

drivers/net/ethernet/intel/i40e/i40e_txrx.h

@@ -218,6 +218,7 @@ struct i40e_ring {
 
 	/* stats structs */
 	struct i40e_queue_stats	stats;
+	struct u64_stats_sync syncp;
 	union {
 		struct i40e_tx_queue_stats tx_stats;
 		struct i40e_rx_queue_stats rx_stats;