diff options
| author | Ben Hutchings <bhutchings@solarflare.com> | 2011-09-02 23:23:00 +0100 |
|---|---|---|
| committer | Ben Hutchings <bhutchings@solarflare.com> | 2012-01-27 00:10:45 +0000 |
| commit | 1cb345220f135dcca24f01cc04cbb97a8242d419 (patch) | |
| tree | 059ec907cd50bd10114bd942d0ffbfa7fd080aa2 | |
| parent | 788ec41cc843f12e8d0eba5f2b37af18b76654a5 (diff) | |
| download | lwn-1cb345220f135dcca24f01cc04cbb97a8242d419.tar.gz lwn-1cb345220f135dcca24f01cc04cbb97a8242d419.zip | |
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>
| -rw-r--r-- | drivers/net/ethernet/sfc/efx.c | 4 | ||||
| -rw-r--r-- | drivers/net/ethernet/sfc/ethtool.c | 7 | ||||
| -rw-r--r-- | 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 eff5d300aa0a..8f4cbb642bf2 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 52c9ee4c8aa3..55a25b14d304 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 9353ce801752..b6040141ef79 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. */ |