diff options
| -rw-r--r-- | drivers/net/ethernet/sfc/falcon_xmac.c | 12 | ||||
| -rw-r--r-- | drivers/net/ethernet/sfc/nic.h | 18 | ||||
| -rw-r--r-- | drivers/net/ethernet/sfc/siena.c | 8 |
3 files changed, 28 insertions, 10 deletions
diff --git a/drivers/net/ethernet/sfc/falcon_xmac.c b/drivers/net/ethernet/sfc/falcon_xmac.c index 6106ef15dee3..8333865d4c95 100644 --- a/drivers/net/ethernet/sfc/falcon_xmac.c +++ b/drivers/net/ethernet/sfc/falcon_xmac.c @@ -341,12 +341,12 @@ void falcon_update_stats_xmac(struct efx_nic *efx) FALCON_STAT(efx, XgTxIpSrcErrPkt, tx_ip_src_error); /* Update derived statistics */ - mac_stats->tx_good_bytes = - (mac_stats->tx_bytes - mac_stats->tx_bad_bytes - - mac_stats->tx_control * 64); - mac_stats->rx_bad_bytes = - (mac_stats->rx_bytes - mac_stats->rx_good_bytes - - mac_stats->rx_control * 64); + efx_update_diff_stat(&mac_stats->tx_good_bytes, + mac_stats->tx_bytes - mac_stats->tx_bad_bytes - + mac_stats->tx_control * 64); + efx_update_diff_stat(&mac_stats->rx_bad_bytes, + mac_stats->rx_bytes - mac_stats->rx_good_bytes - + mac_stats->rx_control * 64); } void falcon_poll_xmac(struct efx_nic *efx) diff --git a/drivers/net/ethernet/sfc/nic.h b/drivers/net/ethernet/sfc/nic.h index f48ccf6bb3b9..bab5cd9f5740 100644 --- a/drivers/net/ethernet/sfc/nic.h +++ b/drivers/net/ethernet/sfc/nic.h @@ -294,6 +294,24 @@ extern bool falcon_xmac_check_fault(struct efx_nic *efx); extern int falcon_reconfigure_xmac(struct efx_nic *efx); extern void falcon_update_stats_xmac(struct efx_nic *efx); +/* Some statistics are computed as A - B where A and B each increase + * linearly with some hardware counter(s) and the counters are read + * asynchronously. If the counters contributing to B are always read + * after those contributing to A, the computed value may be lower than + * the true value by some variable amount, and may decrease between + * subsequent computations. + * + * We should never allow statistics to decrease or to exceed the true + * value. Since the computed value will never be greater than the + * true value, we can achieve this by only storing the computed value + * when it increases. + */ +static inline void efx_update_diff_stat(u64 *stat, u64 diff) +{ + if ((s64)(diff - *stat) > 0) + *stat = diff; +} + /* Interrupts and test events */ extern int efx_nic_init_interrupt(struct efx_nic *efx); extern void efx_nic_enable_interrupts(struct efx_nic *efx); diff --git a/drivers/net/ethernet/sfc/siena.c b/drivers/net/ethernet/sfc/siena.c index 2354886293db..6bafd216e55e 100644 --- a/drivers/net/ethernet/sfc/siena.c +++ b/drivers/net/ethernet/sfc/siena.c @@ -458,8 +458,8 @@ static int siena_try_update_nic_stats(struct efx_nic *efx) 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 @@ static int siena_try_update_nic_stats(struct efx_nic *efx) 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); |