sfc: Hold efx_nic::stats_lock while reading efx_nic::mac_stats
efx_nic::stats_lock is used to serialise stats updates, but each reader was dropping it before it finished reading efx_nic::mac_stats. If there were concurrent stats reads using procfs, or one using procfs and one using ethtool, an update could race with a read. On a 32-bit system, the reader could see word-tearing of 64-bit stats (32 bits of the old value and 32 bits of the new). Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
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@ -1743,8 +1743,8 @@ static struct rtnl_link_stats64 *efx_net_stats(struct net_device *net_dev, struc
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struct efx_mac_stats *mac_stats = &efx->mac_stats;
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spin_lock_bh(&efx->stats_lock);
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efx->type->update_stats(efx);
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spin_unlock_bh(&efx->stats_lock);
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stats->rx_packets = mac_stats->rx_packets;
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stats->tx_packets = mac_stats->tx_packets;
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@ -1768,6 +1768,8 @@ static struct rtnl_link_stats64 *efx_net_stats(struct net_device *net_dev, struc
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stats->tx_errors = (stats->tx_window_errors +
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mac_stats->tx_bad);
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spin_unlock_bh(&efx->stats_lock);
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return stats;
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}
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@ -489,13 +489,14 @@ static void efx_ethtool_get_stats(struct net_device *net_dev,
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const struct efx_ethtool_stat *stat;
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struct efx_channel *channel;
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struct efx_tx_queue *tx_queue;
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struct rtnl_link_stats64 temp;
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int i;
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EFX_BUG_ON_PARANOID(stats->n_stats != EFX_ETHTOOL_NUM_STATS);
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spin_lock_bh(&efx->stats_lock);
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/* Update MAC and NIC statistics */
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dev_get_stats(net_dev, &temp);
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efx->type->update_stats(efx);
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/* Fill detailed statistics buffer */
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for (i = 0; i < EFX_ETHTOOL_NUM_STATS; i++) {
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@ -525,6 +526,8 @@ static void efx_ethtool_get_stats(struct net_device *net_dev,
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break;
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}
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}
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spin_unlock_bh(&efx->stats_lock);
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}
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static void efx_ethtool_self_test(struct net_device *net_dev,
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@ -704,6 +704,7 @@ struct efx_filter_state;
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* can provide. Generic code converts these into a standard
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* &struct net_device_stats.
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* @stats_lock: Statistics update lock. Serialises statistics fetches
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* and access to @mac_stats.
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*
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* This is stored in the private area of the &struct net_device.
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*/
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