Subject: Re: [PATCH net-next v3] bonding: make global bonding stats more reliable

From: Ding Tianhong <[email-masked]>
Date: Mon, 29 Sep 2014 11:52:33 +0800

On 2014/9/26 9:12, Andy Gospodarek wrote:
> 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.
> 
> v2: Changes suggested by Nik to properly allocate/free stats memory.
> v3: Properly destroy workqueue and fix netlink configuration path.
> 
> Signed-off-by: Andy Gospodarek <[email-masked]>
> ---
>  drivers/net/bonding/bond_main.c    | 84 +++++++++++++++++++++++++-------------
>  drivers/net/bonding/bond_netlink.c | 13 +++++-
>  drivers/net/bonding/bonding.h      |  3 ++
>  3 files changed, 71 insertions(+), 29 deletions(-)
> 
> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
> index 5390475..10c2dc3 100644
> --- a/drivers/net/bonding/bond_main.c
> +++ b/drivers/net/bonding/bond_main.c
> @@ -1147,17 +1147,26 @@ static struct slave *bond_alloc_slave(struct bonding *bond)
>  
>  	slave = kzalloc(sizeof(struct slave), GFP_KERNEL);
>  	if (!slave)
> -		return NULL;
> +		goto slave_fail;
> +
> +	slave->slave_stats = kzalloc(sizeof(struct rtnl_link_stats64),
> +				     GFP_KERNEL);
> +	if (!slave->slave_stats)
> +		goto slave_stats_fail;
>  
>  	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);
> -			return NULL;
> -		}
> +		if (!SLAVE_AD_INFO(slave))
> +			goto slave_ad_fail;
>  	}
>  	return slave;
> +slave_ad_fail:
> +	kfree(slave->slave_stats);
> +slave_stats_fail:
> +	kfree(slave);
> +slave_fail:
> +	return NULL;
>  }
>  
>  static void bond_free_slave(struct slave *slave)
> @@ -1167,6 +1176,7 @@ 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 +1354,8 @@ 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 +3097,43 @@ 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;
>  }
> @@ -3790,6 +3807,9 @@ static void bond_destructor(struct net_device *bond_dev)
>  	struct bonding *bond = netdev_priv(bond_dev);
>  	if (bond->wq)
>  		destroy_workqueue(bond->wq);
> +	if (bond->bond_stats)
> +		kfree(bond->bond_stats);
> +
>  	free_netdev(bond_dev);
>  }
>  
> @@ -4274,7 +4294,8 @@ unsigned int bond_get_num_tx_queues(void)
>  int bond_create(struct net *net, const char *name)
>  {
>  	struct net_device *bond_dev;
> -	int res;
> +	struct bonding *bond;
> +	int res = -ENOMEM;
>  
>  	rtnl_lock();
>  
> @@ -4286,8 +4307,15 @@ int bond_create(struct net *net, const char *name)
>  		rtnl_unlock();
>  		return -ENOMEM;
>  	}
> +	/* alloc persistent stats for the bond */
> +	bond = netdev_priv(bond_dev);
> +	bond->bond_stats = kzalloc(sizeof(struct rtnl_link_stats64),
> +				   GFP_KERNEL);
> +	if (!bond->bond_stats)
> +		printk(KERN_CRIT "Stats not available!\n");
>  
hi Andy:

why not return here, otherwise terrible things will happen, later other code will access this point directly.

Ding

>  	dev_net_set(bond_dev, net);
> +
>  	bond_dev->rtnl_link_ops = &bond_link_ops;
>  
>  	res = register_netdevice(bond_dev);
> diff --git a/drivers/net/bonding/bond_netlink.c b/drivers/net/bonding/bond_netlink.c
> index c13d83e..2fdcbe2 100644
> --- a/drivers/net/bonding/bond_netlink.c
> +++ b/drivers/net/bonding/bond_netlink.c
> @@ -381,10 +381,21 @@ static int bond_newlink(struct net *src_net, struct net_device *bond_dev,
>  			struct nlattr *tb[], struct nlattr *data[])
>  {
>  	int err;
> +	struct bonding *bond = netdev_priv(bond_dev);
> +
> +	/* alloc persistent stats for the bond if not already allocated */
> +	if (!bond->bond_stats) {
> +		bond->bond_stats = kzalloc(sizeof(struct rtnl_link_stats64),
> +					   GFP_KERNEL);
> +		if (!bond->bond_stats)
> +			return -ENOMEM;
> +	}
>  
>  	err = bond_changelink(bond_dev, tb, data);
> -	if (err < 0)
> +	if (err < 0) {
> +		kfree(bond->bond_stats);
>  		return err;
> +	}
>  
>  	return register_netdevice(bond_dev);
>  }
> 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) \
>