[PATCH iwl-next v3] i40e: Clear stats after deleting tc

[PATCH iwl-next v3] i40e: Clear stats after deleting tc

[Jedrzej Jagielski]

From: Grzegorz Szczurek <grzegorzx.szczurek@intel.com>

There was an issue with ethtool stats that have not been cleared after tc
had been deleted. Stats printed by ethtool -S remained the same despite
qdisc had been removed, what is an unexpected behavior.
Stats should be reset once the qdisc is removed.

Fix this by resetting stats after deleting tc by calling
i40e_vsi_reset_stats() function after destroying qdisc.

Steps to reproduce:

1) Add ingress rule
tc qdisc add dev <ethX> ingress

2) Create qdisc and filter
tc qdisc add dev <ethX> root mqprio num_tc 4 map 0 0 0 0 1 2 2 3 queues 2@0 2@2 1@4 1@5 hw 1 mode channel
tc filter add dev <ethX> protocol ip parent ffff: prio 3 flower dst_ip <ip> ip_proto tcp dst_port 8300 skip_sw hw_tc 2

3) Run iperf between client and SUT
iperf3 -s -p 8300
iperf3 -c <ip> -p 8300

4) Check the ethtool stats
ethtool -S <ethX> | grep packets | column

5) Delete filter and qdisc
tc filter del dev <ethX> parent ffff:
tc qdisc del dev <ethX> root

6) Check the ethtool stats and see that they didn't change
ethtool -S <ethX> | grep packets | column

Signed-off-by: Grzegorz Szczurek <grzegorzx.szczurek@intel.com>
Signed-off-by: Jedrzej Jagielski <jedrzej.jagielski@intel.com>
---
v2: Make the commit msg more detailed
v3: Correct the commit msg
---
 drivers/net/ethernet/intel/i40e/i40e_main.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
index 29ad1797adce..e8e03ede1672 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_main.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
@@ -5885,6 +5885,11 @@ static int i40e_vsi_config_tc(struct i40e_vsi *vsi, u8 enabled_tc)
 
 	/* Update the netdev TC setup */
 	i40e_vsi_config_netdev_tc(vsi, enabled_tc);
+
+	/* After destroying qdisc reset all stats of the vsi */
+	if (!vsi->mqprio_qopt.qopt.hw)
+		i40e_vsi_reset_stats(vsi);
+
 out:
 	return ret;
 }
-- 
2.31.1

Re: [PATCH iwl-next v3] i40e: Clear stats after deleting tc

[Simon Horman]

On Mon, Jul 31, 2023 at 03:52:18PM +0200, Jedrzej Jagielski wrote:
> From: Grzegorz Szczurek <grzegorzx.szczurek@intel.com>
> 
> There was an issue with ethtool stats that have not been cleared after tc
> had been deleted. Stats printed by ethtool -S remained the same despite
> qdisc had been removed, what is an unexpected behavior.
> Stats should be reset once the qdisc is removed.
> 
> Fix this by resetting stats after deleting tc by calling
> i40e_vsi_reset_stats() function after destroying qdisc.
> 
> Steps to reproduce:
> 
> 1) Add ingress rule
> tc qdisc add dev <ethX> ingress
> 
> 2) Create qdisc and filter
> tc qdisc add dev <ethX> root mqprio num_tc 4 map 0 0 0 0 1 2 2 3 queues 2@0 2@2 1@4 1@5 hw 1 mode channel
> tc filter add dev <ethX> protocol ip parent ffff: prio 3 flower dst_ip <ip> ip_proto tcp dst_port 8300 skip_sw hw_tc 2
> 
> 3) Run iperf between client and SUT
> iperf3 -s -p 8300
> iperf3 -c <ip> -p 8300
> 
> 4) Check the ethtool stats
> ethtool -S <ethX> | grep packets | column
> 
> 5) Delete filter and qdisc
> tc filter del dev <ethX> parent ffff:
> tc qdisc del dev <ethX> root
> 
> 6) Check the ethtool stats and see that they didn't change
> ethtool -S <ethX> | grep packets | column
> 
> Signed-off-by: Grzegorz Szczurek <grzegorzx.szczurek@intel.com>
> Signed-off-by: Jedrzej Jagielski <jedrzej.jagielski@intel.com>

Reviewed-by: Simon Horman <horms@kernel.org>