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>
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 @@
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 @@
break;
}
}
+
+ spin_unlock_bh(&efx->stats_lock);
}
static void efx_ethtool_self_test(struct net_device *net_dev,