linux-kernel - [PATCH 5.4 29/83] net/mlx5e: Get the latest values from counters in switchdev mode

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Date:   Fri,  1 May 2020 15:23:08 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Zhu Yanjun <yanjunz@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: [PATCH 5.4 29/83] net/mlx5e: Get the latest values from counters in switchdev mode

From: Zhu Yanjun <yanjunz@...lanox.com>

commit dcdf4ce0ff4ba206fc362e149c8ae81d6a2f849c upstream.

In the switchdev mode, when running "cat
/sys/class/net/NIC/statistics/tx_packets", the ppcnt register is
accessed to get the latest values. But currently this command can
not get the correct values from ppcnt.

>>From firmware manual, before getting the 802_3 counters, the 802_3
data layout should be set to the ppcnt register.

When the command "cat /sys/class/net/NIC/statistics/tx_packets" is
run, before updating 802_3 data layout with ppcnt register, the
monitor counters are tested. The test result will decide the
802_3 data layout is updated or not.

Actually the monitor counters do not support to monitor rx/tx
stats of 802_3 in switchdev mode. So the rx/tx counters change
will not trigger monitor counters. So the 802_3 data layout will
not be updated in ppcnt register. Finally this command can not get
the latest values from ppcnt register with 802_3 data layout.

Fixes: 5c7e8bbb0257 ("net/mlx5e: Use monitor counters for update stats")
Signed-off-by: Zhu Yanjun <yanjunz@...lanox.com>
Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/ethernet/mellanox/mlx5/core/en_main.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -3579,7 +3579,12 @@ mlx5e_get_stats(struct net_device *dev,
 	struct mlx5e_vport_stats *vstats = &priv->stats.vport;
 	struct mlx5e_pport_stats *pstats = &priv->stats.pport;

-	if (!mlx5e_monitor_counter_supported(priv)) {
+	/* In switchdev mode, monitor counters doesn't monitor
+	 * rx/tx stats of 802_3. The update stats mechanism
+	 * should keep the 802_3 layout counters updated
+	 */
+	if (!mlx5e_monitor_counter_supported(priv) ||
+	    mlx5e_is_uplink_rep(priv)) {
 		/* update HW stats in background for next time */
 		mlx5e_queue_update_stats(priv);
 	}