From 3cfde79c6c7c8002375c4a8e5be7f602fbb9675d Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Fri, 9 Jul 2010 09:11:52 +0000 Subject: net: Get rid of rtnl_link_stats64 / net_device_stats union In commit be1f3c2c027cc5ad735df6a45a542ed1db7ec48b "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 28172739f0a276eb8d6ca917b3974c2edb036da3 "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: Ben Hutchings Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- net/8021q/vlan_dev.c | 2 +- net/core/dev.c | 31 ++++++++++++++++++++++++++----- 2 files changed, 27 insertions(+), 6 deletions(-) (limited to 'net') diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c index a1b8171cfa7b..7cb285f96b99 100644 --- a/net/8021q/vlan_dev.c +++ b/net/8021q/vlan_dev.c @@ -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}; diff --git a/net/core/dev.c b/net/core/dev.c index eb4201cf9c8c..79ee26ef5095 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -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); -- cgit v1.2.3