[PATCH net-next 12/32] sfc: Hold efx_nic::stats_lock while reading efx_nic::mac_stats
From: Ben Hutchings <hidden>
Date: 2012-01-27 20:45:41
Subsystem:
networking drivers, sfc network driver, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Edward Cree, Linus Torvalds
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 <redacted> --- drivers/net/ethernet/sfc/efx.c | 4 +++- drivers/net/ethernet/sfc/ethtool.c | 7 +++++-- drivers/net/ethernet/sfc/net_driver.h | 1 + 3 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/sfc/efx.c b/drivers/net/ethernet/sfc/efx.c
index eff5d30..8f4cbb6 100644
--- a/drivers/net/ethernet/sfc/efx.c
+++ b/drivers/net/ethernet/sfc/efx.c@@ -1743,8 +1743,8 @@ static struct rtnl_link_stats64 *efx_net_stats(struct net_device *net_dev, struc struct efx_mac_stats *mac_stats = &efx->mac_stats; spin_lock_bh(&efx->stats_lock); + efx->type->update_stats(efx); - spin_unlock_bh(&efx->stats_lock); stats->rx_packets = mac_stats->rx_packets; stats->tx_packets = mac_stats->tx_packets;
@@ -1768,6 +1768,8 @@ static struct rtnl_link_stats64 *efx_net_stats(struct net_device *net_dev, struc stats->tx_errors = (stats->tx_window_errors + mac_stats->tx_bad); + spin_unlock_bh(&efx->stats_lock); + return stats; }
diff --git a/drivers/net/ethernet/sfc/ethtool.c b/drivers/net/ethernet/sfc/ethtool.c
index 52c9ee4..55a25b1 100644
--- a/drivers/net/ethernet/sfc/ethtool.c
+++ b/drivers/net/ethernet/sfc/ethtool.c@@ -489,13 +489,14 @@ static void efx_ethtool_get_stats(struct net_device *net_dev, const struct efx_ethtool_stat *stat; struct efx_channel *channel; struct efx_tx_queue *tx_queue; - struct rtnl_link_stats64 temp; int i; EFX_BUG_ON_PARANOID(stats->n_stats != EFX_ETHTOOL_NUM_STATS); + spin_lock_bh(&efx->stats_lock); + /* Update MAC and NIC statistics */ - dev_get_stats(net_dev, &temp); + efx->type->update_stats(efx); /* Fill detailed statistics buffer */ for (i = 0; i < EFX_ETHTOOL_NUM_STATS; i++) {
@@ -525,6 +526,8 @@ static void efx_ethtool_get_stats(struct net_device *net_dev, break; } } + + spin_unlock_bh(&efx->stats_lock); } static void efx_ethtool_self_test(struct net_device *net_dev,
diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h
index 9353ce8..b604014 100644
--- a/drivers/net/ethernet/sfc/net_driver.h
+++ b/drivers/net/ethernet/sfc/net_driver.h@@ -704,6 +704,7 @@ struct efx_filter_state; * can provide. Generic code converts these into a standard * &struct net_device_stats. * @stats_lock: Statistics update lock. Serialises statistics fetches + * and access to @mac_stats. * * This is stored in the private area of the &struct net_device. */
--
1.7.7.5
--
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.