[PATCH net-next] bonding: make global bonding stats more reliable

[Andy Gospodarek <gospo@cumulusnetworks.com>]

As the code stands today, bonding stats are based simply on the stats
from the member interfaces.  If a member was to be removed from a bond,
the stats would instantly drop.  This would be confusing to an admin
would would suddonly see interface stats drop while traffic is still
flowing.

In addition to preventing the stats drops mentioned above, new members
will now be added to the bond and only traffic received after the member
was added to the bond will be counted as part of bonding stats.

Signed-off-by: Andy Gospodarek <gospo@cumulusnetworks.com>
---
 drivers/net/bonding/bond_main.c | 63 +++++++++++++++++++++++++++--------------
 drivers/net/bonding/bonding.h   |  3 ++
 2 files changed, 44 insertions(+), 22 deletions(-)

diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
index 5390475..4543c74 100644
--- a/drivers/net/bonding/bond_main.c
+++ b/drivers/net/bonding/bond_main.c
@@ -1149,11 +1149,19 @@ static struct slave *bond_alloc_slave(struct bonding *bond)
 	if (!slave)
 		return NULL;
 
+	slave->slave_stats = kzalloc(sizeof(struct rtnl_link_stats64),
+				     GFP_KERNEL);
+	if (!slave->slave_stats) {
+		kfree(slave);
+		return NULL;
+	}
+
 	if (BOND_MODE(bond) == BOND_MODE_8023AD) {
 		SLAVE_AD_INFO(slave) = kzalloc(sizeof(struct ad_slave_info),
 					       GFP_KERNEL);
 		if (!SLAVE_AD_INFO(slave)) {
 			kfree(slave);
+			kfree(slave->slave_stats);
 			return NULL;
 		}
 	}
@@ -1167,6 +1175,7 @@ static void bond_free_slave(struct slave *slave)
 	if (BOND_MODE(bond) == BOND_MODE_8023AD)
 		kfree(SLAVE_AD_INFO(slave));
 
+	kfree(slave->slave_stats);
 	kfree(slave);
 }
 
@@ -1344,6 +1353,8 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
 	}
 
 	slave_dev->priv_flags |= IFF_BONDING;
+	/* initialize slave stats */
+	dev_get_stats(new_slave->dev, new_slave->slave_stats);
 
 	if (bond_is_lb(bond)) {
 		/* bond_alb_init_slave() must be called before all other stages since
@@ -3085,38 +3096,43 @@ static struct rtnl_link_stats64 *bond_get_stats(struct net_device *bond_dev,
 	struct list_head *iter;
 	struct slave *slave;
 
-	memset(stats, 0, sizeof(*stats));
+	memcpy(stats, bond->bond_stats, sizeof(*stats));
 
 	bond_for_each_slave(bond, slave, iter) {
 		const struct rtnl_link_stats64 *sstats =
 			dev_get_stats(slave->dev, &temp);
+		struct rtnl_link_stats64 *pstats = slave->slave_stats;
+
+		stats->rx_packets +=  sstats->rx_packets - pstats->rx_packets;
+		stats->rx_bytes += sstats->rx_bytes - pstats->rx_bytes;
+		stats->rx_errors += sstats->rx_errors - pstats->rx_errors;
+		stats->rx_dropped += sstats->rx_dropped - pstats->rx_dropped;
 
-		stats->rx_packets += sstats->rx_packets;
-		stats->rx_bytes += sstats->rx_bytes;
-		stats->rx_errors += sstats->rx_errors;
-		stats->rx_dropped += sstats->rx_dropped;
+		stats->tx_packets += sstats->tx_packets - pstats->tx_packets;;
+		stats->tx_bytes += sstats->tx_bytes - pstats->tx_bytes;
+		stats->tx_errors += sstats->tx_errors - pstats->tx_errors;
+		stats->tx_dropped += sstats->tx_dropped - pstats->tx_dropped;
 
-		stats->tx_packets += sstats->tx_packets;
-		stats->tx_bytes += sstats->tx_bytes;
-		stats->tx_errors += sstats->tx_errors;
-		stats->tx_dropped += sstats->tx_dropped;
+		stats->multicast += sstats->multicast - pstats->multicast;
+		stats->collisions += sstats->collisions - pstats->collisions;
 
-		stats->multicast += sstats->multicast;
-		stats->collisions += sstats->collisions;
+		stats->rx_length_errors += sstats->rx_length_errors - pstats->rx_length_errors;
+		stats->rx_over_errors += sstats->rx_over_errors - pstats->rx_over_errors;
+		stats->rx_crc_errors += sstats->rx_crc_errors - pstats->rx_crc_errors;
+		stats->rx_frame_errors += sstats->rx_frame_errors - pstats->rx_frame_errors;
+		stats->rx_fifo_errors += sstats->rx_fifo_errors - pstats->rx_fifo_errors;
+		stats->rx_missed_errors += sstats->rx_missed_errors - pstats->rx_missed_errors;
 
-		stats->rx_length_errors += sstats->rx_length_errors;
-		stats->rx_over_errors += sstats->rx_over_errors;
-		stats->rx_crc_errors += sstats->rx_crc_errors;
-		stats->rx_frame_errors += sstats->rx_frame_errors;
-		stats->rx_fifo_errors += sstats->rx_fifo_errors;
-		stats->rx_missed_errors += sstats->rx_missed_errors;
+		stats->tx_aborted_errors += sstats->tx_aborted_errors - pstats->tx_aborted_errors;
+		stats->tx_carrier_errors += sstats->tx_carrier_errors - pstats->tx_carrier_errors;
+		stats->tx_fifo_errors += sstats->tx_fifo_errors - pstats->tx_fifo_errors;
+		stats->tx_heartbeat_errors += sstats->tx_heartbeat_errors - pstats->tx_heartbeat_errors;
+		stats->tx_window_errors += sstats->tx_window_errors - pstats->tx_window_errors;
 
-		stats->tx_aborted_errors += sstats->tx_aborted_errors;
-		stats->tx_carrier_errors += sstats->tx_carrier_errors;
-		stats->tx_fifo_errors += sstats->tx_fifo_errors;
-		stats->tx_heartbeat_errors += sstats->tx_heartbeat_errors;
-		stats->tx_window_errors += sstats->tx_window_errors;
+		/* save off the slave stats for the next run */
+		memcpy(pstats, sstats, sizeof(*sstats));
 	}
+	memcpy(bond->bond_stats, stats, sizeof(*stats));
 
 	return stats;
 }
@@ -4258,6 +4274,9 @@ static int bond_init(struct net_device *bond_dev)
 	    bond_dev->addr_assign_type == NET_ADDR_PERM)
 		eth_hw_addr_random(bond_dev);
 
+	/* initialize persistent stats for the bond */
+	bond->bond_stats = kzalloc(sizeof(struct rtnl_link_stats64),
+				   GFP_ATOMIC);
 	return 0;
 }
 
diff --git a/drivers/net/bonding/bonding.h b/drivers/net/bonding/bonding.h
index 6140bf0..fe25265 100644
--- a/drivers/net/bonding/bonding.h
+++ b/drivers/net/bonding/bonding.h
@@ -24,6 +24,7 @@
 #include <linux/inetdevice.h>
 #include <linux/etherdevice.h>
 #include <linux/reciprocal_div.h>
+#include <linux/if_link.h>
 
 #include "bond_3ad.h"
 #include "bond_alb.h"
@@ -175,6 +176,7 @@ struct slave {
 	struct netpoll *np;
 #endif
 	struct kobject kobj;
+	struct rtnl_link_stats64 *slave_stats;
 };
 
 /*
@@ -224,6 +226,7 @@ struct bonding {
 	/* debugging support via debugfs */
 	struct	 dentry *debug_dir;
 #endif /* CONFIG_DEBUG_FS */
+	struct rtnl_link_stats64 *bond_stats;
 };
 
 #define bond_slave_get_rcu(dev) \
-- 
1.9.3