net: fix 64 bit counters on 32 bit arches
There is a small possibility that a reader gets incorrect values on 32
bit arches. SNMP applications could catch incorrect counters when a
32bit high part is changed by another stats consumer/provider.
One way to solve this is to add a rtnl_link_stats64 param to all
ndo_get_stats64() methods, and also add such a parameter to
dev_get_stats().
Rule is that we are not allowed to use dev->stats64 as a temporary
storage for 64bit stats, but a caller provided area (usually on stack)
Old drivers (only providing get_stats() method) need no changes.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/dev.c b/net/core/dev.c
index 93b8929f..92482d7 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3703,7 +3703,8 @@
static void dev_seq_printf_stats(struct seq_file *seq, struct net_device *dev)
{
- const struct rtnl_link_stats64 *stats = dev_get_stats(dev);
+ struct rtnl_link_stats64 temp;
+ const struct rtnl_link_stats64 *stats = dev_get_stats(dev, &temp);
seq_printf(seq, "%6s: %7llu %7llu %4llu %4llu %4llu %5llu %10llu %9llu "
"%8llu %7llu %4llu %4llu %4llu %5llu %7llu %10llu\n",
@@ -5281,23 +5282,29 @@
/**
* dev_get_stats - get network device statistics
* @dev: device to get statistics from
+ * @storage: place to store stats
*
* Get network statistics from device. The device driver may provide
* its own method by setting dev->netdev_ops->get_stats64 or
* dev->netdev_ops->get_stats; otherwise the internal statistics
* structure is used.
*/
-const struct rtnl_link_stats64 *dev_get_stats(struct net_device *dev)
+const struct rtnl_link_stats64 *dev_get_stats(struct net_device *dev,
+ struct rtnl_link_stats64 *storage)
{
const struct net_device_ops *ops = dev->netdev_ops;
- if (ops->ndo_get_stats64)
- return ops->ndo_get_stats64(dev);
- if (ops->ndo_get_stats)
- return (struct rtnl_link_stats64 *)ops->ndo_get_stats(dev);
-
- dev_txq_stats_fold(dev, &dev->stats);
- return &dev->stats64;
+ if (ops->ndo_get_stats64) {
+ memset(storage, 0, sizeof(*storage));
+ return ops->ndo_get_stats64(dev, storage);
+ }
+ if (ops->ndo_get_stats) {
+ memcpy(storage, ops->ndo_get_stats(dev), sizeof(*storage));
+ return storage;
+ }
+ memcpy(storage, &dev->stats, sizeof(*storage));
+ dev_txq_stats_fold(dev, (struct net_device_stats *)storage);
+ return storage;
}
EXPORT_SYMBOL(dev_get_stats);