sfc: Fix interface statistics running backward
Some interface statistics are computed in such a way that they can
sometimes decrease (and even underflow). Since the computed value
will never be greater than the true value, we fix this by only storing
the computed value when it increases.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
diff --git a/drivers/net/ethernet/sfc/siena.c b/drivers/net/ethernet/sfc/siena.c
index 2354886..6bafd21 100644
--- a/drivers/net/ethernet/sfc/siena.c
+++ b/drivers/net/ethernet/sfc/siena.c
@@ -458,8 +458,8 @@
MAC_STAT(tx_bytes, TX_BYTES);
MAC_STAT(tx_bad_bytes, TX_BAD_BYTES);
- mac_stats->tx_good_bytes = (mac_stats->tx_bytes -
- mac_stats->tx_bad_bytes);
+ efx_update_diff_stat(&mac_stats->tx_good_bytes,
+ mac_stats->tx_bytes - mac_stats->tx_bad_bytes);
MAC_STAT(tx_packets, TX_PKTS);
MAC_STAT(tx_bad, TX_BAD_FCS_PKTS);
MAC_STAT(tx_pause, TX_PAUSE_PKTS);
@@ -492,8 +492,8 @@
MAC_STAT(tx_ip_src_error, TX_IP_SRC_ERR_PKTS);
MAC_STAT(rx_bytes, RX_BYTES);
MAC_STAT(rx_bad_bytes, RX_BAD_BYTES);
- mac_stats->rx_good_bytes = (mac_stats->rx_bytes -
- mac_stats->rx_bad_bytes);
+ efx_update_diff_stat(&mac_stats->rx_good_bytes,
+ mac_stats->rx_bytes - mac_stats->rx_bad_bytes);
MAC_STAT(rx_packets, RX_PKTS);
MAC_STAT(rx_good, RX_GOOD_PKTS);
MAC_STAT(rx_bad, RX_BAD_FCS_PKTS);