net/sfc: fix Rx packets counter

Errors, missed and pauses should not be included in delivered
good Rx packets reported by ipackets.

Fixes: 1caab2f1e684 ("net/sfc: add basic statistics")
Cc: stable@dpdk.org
Signed-off-by: Andrew Rybchenko <arybchenko@solarflare.com>

diff --git a/drivers/net/sfc/sfc.h b/drivers/net/sfc/sfc.h
index 0b85234..a94ca8e 100644 (file)
--- a/drivers/net/sfc/sfc.h
+++ b/drivers/net/sfc/sfc.h
@@ -149,6 +149,8 @@ struct sfc_port {
        uint64_t                        mac_stats_last_request_timestamp;
 
        uint32_t                mac_stats_mask[EFX_MAC_STATS_MASK_NPAGES];
+
+       uint64_t                        ipackets;
 };
 
 struct sfc_rss_hf_rte_to_efx {

diff --git a/drivers/net/sfc/sfc_ethdev.c b/drivers/net/sfc/sfc_ethdev.c
index 08d3271..a7322a1 100644 (file)
--- a/drivers/net/sfc/sfc_ethdev.c
+++ b/drivers/net/sfc/sfc_ethdev.c
@@ -503,6 +503,29 @@ sfc_tx_queue_release(void *queue)
        sfc_adapter_unlock(sa);
 }
 
+/*
+ * Some statistics are computed as A - B where A and B each increase
+ * monotonically with some hardware counter(s) and the counters are read
+ * asynchronously.
+ *
+ * If packet X is counted in A, but not counted in B yet, computed value is
+ * greater than real.
+ *
+ * If packet X is not counted in A at the moment of reading the counter,
+ * but counted in B at the moment of reading the counter, computed value
+ * is less than real.
+ *
+ * However, counter which grows backward is worse evil than slightly wrong
+ * value. So, let's try to guarantee that it never happens except may be
+ * the case when the MAC stats are zeroed as a result of a NIC reset.
+ */
+static void
+sfc_update_diff_stat(uint64_t *stat, uint64_t newval)
+{
+       if ((int64_t)(newval - *stat) > 0 || newval == 0)
+               *stat = newval;
+}
+
 static int
 sfc_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats)
 {
@@ -540,7 +563,6 @@ sfc_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats)
                stats->imissed = mac_stats[EFX_MAC_VADAPTER_RX_BAD_PACKETS];
                stats->oerrors = mac_stats[EFX_MAC_VADAPTER_TX_BAD_PACKETS];
        } else {
-               stats->ipackets = mac_stats[EFX_MAC_RX_PKTS];
                stats->opackets = mac_stats[EFX_MAC_TX_PKTS];
                stats->ibytes = mac_stats[EFX_MAC_RX_OCTETS];
                stats->obytes = mac_stats[EFX_MAC_TX_OCTETS];
@@ -566,6 +588,13 @@ sfc_stats_get(struct rte_eth_dev *dev, struct rte_eth_stats *stats)
                        mac_stats[EFX_MAC_RX_ALIGN_ERRORS] +
                        mac_stats[EFX_MAC_RX_JABBER_PKTS];
                /* no oerrors counters supported on EF10 */
+
+               /* Exclude missed, errors and pauses from Rx packets */
+               sfc_update_diff_stat(&port->ipackets,
+                       mac_stats[EFX_MAC_RX_PKTS] -
+                       mac_stats[EFX_MAC_RX_PAUSE_PKTS] -
+                       stats->imissed - stats->ierrors);
+               stats->ipackets = port->ipackets;
        }
 
 unlock:

diff --git a/drivers/net/sfc/sfc_port.c b/drivers/net/sfc/sfc_port.c
index 5384dbb..5eb4b3a 100644 (file)
--- a/drivers/net/sfc/sfc_port.c
+++ b/drivers/net/sfc/sfc_port.c
@@ -87,6 +87,18 @@ sfc_port_update_mac_stats(struct sfc_adapter *sa)
        return 0;
 }
 
+static void
+sfc_port_reset_sw_stats(struct sfc_adapter *sa)
+{
+       struct sfc_port *port = &sa->port;
+
+       /*
+        * Reset diff stats explicitly since check which does not allow
+        * the statistics to grow backward could deny it.
+        */
+       port->ipackets = 0;
+}
+
 int
 sfc_port_reset_mac_stats(struct sfc_adapter *sa)
 {
@@ -95,6 +107,8 @@ sfc_port_reset_mac_stats(struct sfc_adapter *sa)
 
        rte_spinlock_lock(&port->mac_stats_lock);
        rc = efx_mac_stats_clear(sa->nic);
+       if (rc == 0)
+               sfc_port_reset_sw_stats(sa);
        rte_spinlock_unlock(&port->mac_stats_lock);
 
        return rc;