Commit 3cfde79c authored by Ben Hutchings's avatar Ben Hutchings Committed by David S. Miller
Browse files

net: Get rid of rtnl_link_stats64 / net_device_stats union 



In commit be1f3c2c "net: Enable 64-bit
net device statistics on 32-bit architectures" I redefined struct
net_device_stats so that it could be used in a union with struct
rtnl_link_stats64, avoiding the need for explicit copying or
conversion between the two.  However, this is unsafe because there is
no locking required and no lock consistently held around calls to
dev_get_stats() and use of the statistics structure it returns.

In commit 28172739 "net: fix 64 bit
counters on 32 bit arches" Eric Dumazet dealt with that problem by
requiring callers of dev_get_stats() to provide storage for the
result.  This means that the net_device::stats64 field and the padding
in struct net_device_stats are now redundant, so remove them.

Update the comment on net_device_ops::ndo_get_stats64 to reflect its
new usage.

Change dev_txq_stats_fold() to use struct rtnl_link_stats64, since
that is what all its callers are really using and it is no longer
going to be compatible with struct net_device_stats.

Eric Dumazet suggested the separate function for the structure
conversion.

Signed-off-by: default avatarBen Hutchings <bhutchings@solarflare.com>
Acked-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent cc7b86c1

drivers/net/macvlan.c

+1 −1
Original line number Diff line number Diff line
@@ -436,7 +436,7 @@ static struct rtnl_link_stats64 *macvlan_dev_get_stats64(struct net_device *dev, 
{

	struct macvlan_dev *vlan = netdev_priv(dev);



	dev_txq_stats_fold(dev, (struct net_device_stats *)stats);

	dev_txq_stats_fold(dev, stats);



	if (vlan->rx_stats) {

		struct macvlan_rx_stats *p, accum = {0};

include/linux/netdevice.h

+28 −42
Original line number Diff line number Diff line
@@ -162,42 +162,32 @@ static inline bool dev_xmit_complete(int rc) 
/*

 *	Old network device statistics. Fields are native words

 *	(unsigned long) so they can be read and written atomically.

 *	Each field is padded to 64 bits for compatibility with

 *	rtnl_link_stats64.

 */



#if BITS_PER_LONG == 64

#define NET_DEVICE_STATS_DEFINE(name)	unsigned long name

#elif defined(__LITTLE_ENDIAN)

#define NET_DEVICE_STATS_DEFINE(name)	unsigned long name, pad_ ## name

#else

#define NET_DEVICE_STATS_DEFINE(name)	unsigned long pad_ ## name, name

#endif



struct net_device_stats {

	NET_DEVICE_STATS_DEFINE(rx_packets);

	NET_DEVICE_STATS_DEFINE(tx_packets);

	NET_DEVICE_STATS_DEFINE(rx_bytes);

	NET_DEVICE_STATS_DEFINE(tx_bytes);

	NET_DEVICE_STATS_DEFINE(rx_errors);

	NET_DEVICE_STATS_DEFINE(tx_errors);

	NET_DEVICE_STATS_DEFINE(rx_dropped);

	NET_DEVICE_STATS_DEFINE(tx_dropped);

	NET_DEVICE_STATS_DEFINE(multicast);

	NET_DEVICE_STATS_DEFINE(collisions);

	NET_DEVICE_STATS_DEFINE(rx_length_errors);

	NET_DEVICE_STATS_DEFINE(rx_over_errors);

	NET_DEVICE_STATS_DEFINE(rx_crc_errors);

	NET_DEVICE_STATS_DEFINE(rx_frame_errors);

	NET_DEVICE_STATS_DEFINE(rx_fifo_errors);

	NET_DEVICE_STATS_DEFINE(rx_missed_errors);

	NET_DEVICE_STATS_DEFINE(tx_aborted_errors);

	NET_DEVICE_STATS_DEFINE(tx_carrier_errors);

	NET_DEVICE_STATS_DEFINE(tx_fifo_errors);

	NET_DEVICE_STATS_DEFINE(tx_heartbeat_errors);

	NET_DEVICE_STATS_DEFINE(tx_window_errors);

	NET_DEVICE_STATS_DEFINE(rx_compressed);

	NET_DEVICE_STATS_DEFINE(tx_compressed);

	unsigned long	rx_packets;

	unsigned long	tx_packets;

	unsigned long	rx_bytes;

	unsigned long	tx_bytes;

	unsigned long	rx_errors;

	unsigned long	tx_errors;

	unsigned long	rx_dropped;

	unsigned long	tx_dropped;

	unsigned long	multicast;

	unsigned long	collisions;

	unsigned long	rx_length_errors;

	unsigned long	rx_over_errors;

	unsigned long	rx_crc_errors;

	unsigned long	rx_frame_errors;

	unsigned long	rx_fifo_errors;

	unsigned long	rx_missed_errors;

	unsigned long	tx_aborted_errors;

	unsigned long	tx_carrier_errors;

	unsigned long	tx_fifo_errors;

	unsigned long	tx_heartbeat_errors;

	unsigned long	tx_window_errors;

	unsigned long	rx_compressed;

	unsigned long	tx_compressed;

};



#endif  /*  __KERNEL__  */
@@ -666,14 +656,13 @@ struct netdev_rx_queue { 
 *	Callback uses when the transmitter has not made any progress

 *	for dev->watchdog ticks.

 *

 * struct rtnl_link_stats64* (*ndo_get_stats64)(struct net_device *dev

 * struct rtnl_link_stats64* (*ndo_get_stats64)(struct net_device *dev,

 *                      struct rtnl_link_stats64 *storage);

 * struct net_device_stats* (*ndo_get_stats)(struct net_device *dev);

 *	Called when a user wants to get the network device usage

 *	statistics. Drivers must do one of the following:

 *	1. Define @ndo_get_stats64 to update a rtnl_link_stats64 structure

 *	   (which should normally be dev->stats64) and return a ponter to

 *	   it. The structure must not be changed asynchronously.

 *	1. Define @ndo_get_stats64 to fill in a zero-initialised

 *	   rtnl_link_stats64 structure passed by the caller.

 *	2. Define @ndo_get_stats to update a net_device_stats structure

 *	   (which should normally be dev->stats) and return a pointer to

 *	   it. The structure may be changed asynchronously only if each
@@ -888,10 +877,7 @@ struct net_device { 
	int			ifindex;

	int			iflink;



	union {

		struct rtnl_link_stats64 stats64;

	struct net_device_stats	stats;

	};



#ifdef CONFIG_WIRELESS_EXT

	/* List of functions to handle Wireless Extensions (instead of ioctl).
@@ -2147,7 +2133,7 @@ extern void dev_mcast_init(void); 
extern const struct rtnl_link_stats64 *dev_get_stats(struct net_device *dev,

						     struct rtnl_link_stats64 *storage);

extern void		dev_txq_stats_fold(const struct net_device *dev,

					   struct net_device_stats *stats);

					   struct rtnl_link_stats64 *stats);



extern int		netdev_max_backlog;

extern int		netdev_tstamp_prequeue;

net/8021q/vlan_dev.c

+1 −1
Original line number Diff line number Diff line
@@ -805,7 +805,7 @@ static u32 vlan_ethtool_get_flags(struct net_device *dev) 


static struct rtnl_link_stats64 *vlan_dev_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats)

{

	dev_txq_stats_fold(dev, (struct net_device_stats *)stats);

	dev_txq_stats_fold(dev, stats);



	if (vlan_dev_info(dev)->vlan_rx_stats) {

		struct vlan_rx_stats *p, accum = {0};

net/core/dev.c

+26 −5
Original line number Diff line number Diff line
@@ -5274,10 +5274,10 @@ void netdev_run_todo(void) 
/**

 *	dev_txq_stats_fold - fold tx_queues stats

 *	@dev: device to get statistics from

 *	@stats: struct net_device_stats to hold results

 *	@stats: struct rtnl_link_stats64 to hold results

 */

void dev_txq_stats_fold(const struct net_device *dev,

			struct net_device_stats *stats)

			struct rtnl_link_stats64 *stats)

{

	unsigned long tx_bytes = 0, tx_packets = 0, tx_dropped = 0;

	unsigned int i;
@@ -5297,6 +5297,27 @@ void dev_txq_stats_fold(const struct net_device *dev, 
}

EXPORT_SYMBOL(dev_txq_stats_fold);



/* Convert net_device_stats to rtnl_link_stats64.  They have the same

 * fields in the same order, with only the type differing.

 */

static void netdev_stats_to_stats64(struct rtnl_link_stats64 *stats64,

				    const struct net_device_stats *netdev_stats)

{

#if BITS_PER_LONG == 64

        BUILD_BUG_ON(sizeof(*stats64) != sizeof(*netdev_stats));

        memcpy(stats64, netdev_stats, sizeof(*stats64));

#else

	size_t i, n = sizeof(*stats64) / sizeof(u64);

	const unsigned long *src = (const unsigned long *)netdev_stats;

	u64 *dst = (u64 *)stats64;



	BUILD_BUG_ON(sizeof(*netdev_stats) / sizeof(unsigned long) !=

		     sizeof(*stats64) / sizeof(u64));

	for (i = 0; i < n; i++)

		dst[i] = src[i];

#endif

}



/**

 *	dev_get_stats	- get network device statistics

 *	@dev: device to get statistics from
@@ -5317,11 +5338,11 @@ const struct rtnl_link_stats64 *dev_get_stats(struct net_device *dev, 
		return ops->ndo_get_stats64(dev, storage);

	}

	if (ops->ndo_get_stats) {

		memcpy(storage, ops->ndo_get_stats(dev), sizeof(*storage));

		netdev_stats_to_stats64(storage, ops->ndo_get_stats(dev));

		return storage;

	}

	memcpy(storage, &dev->stats, sizeof(*storage));

	dev_txq_stats_fold(dev, (struct net_device_stats *)storage);

	netdev_stats_to_stats64(storage, &dev->stats);

	dev_txq_stats_fold(dev, storage);

	return storage;

}

EXPORT_SYMBOL(dev_get_stats);

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