From e2276abeb4ba47b94d4bc3921bdfa0ce5a3085be Mon Sep 17 00:00:00 2001 From: Petr Machata Date: Wed, 15 Jan 2020 13:53:48 +0200 Subject: [PATCH] mlxsw: spectrum: Wipe xstats.backlog of down ports Per-port counter cache used by Qdiscs is updated periodically, unless the port is down. The fact that the cache is not updated for down ports is no problem for most counters, which are relative in nature. However, backlog is absolute in nature, and if there is a non-zero value in the cache around the time that the port goes down, that value just stays there. This value then leaks to offloaded Qdiscs that report non-zero backlog even if there (obviously) is no traffic. The HW does not keep backlog of a downed port, so do likewise: as the port goes down, wipe the backlog value from xstats. Fixes: 7dd377ef4f25 ("mlxsw: spectrum: Collect tclass related stats periodically") Signed-off-by: Petr Machata Acked-by: Jiri Pirko Signed-off-by: Ido Schimmel Signed-off-by: David S. Miller --- drivers/net/ethernet/mellanox/mlxsw/spectrum.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c index 2394c425b47dd..8ed15199eb4f3 100644 --- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.c +++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.c @@ -1209,6 +1209,9 @@ static void update_stats_cache(struct work_struct *work) periodic_hw_stats.update_dw.work); if (!netif_carrier_ok(mlxsw_sp_port->dev)) + /* Note: mlxsw_sp_port_down_wipe_counters() clears the cache as + * necessary when port goes down. + */ goto out; mlxsw_sp_port_get_hw_stats(mlxsw_sp_port->dev, @@ -4318,6 +4321,15 @@ static int mlxsw_sp_port_unsplit(struct mlxsw_core *mlxsw_core, u8 local_port, return 0; } +static void +mlxsw_sp_port_down_wipe_counters(struct mlxsw_sp_port *mlxsw_sp_port) +{ + int i; + + for (i = 0; i < TC_MAX_QUEUE; i++) + mlxsw_sp_port->periodic_hw_stats.xstats.backlog[i] = 0; +} + static void mlxsw_sp_pude_event_func(const struct mlxsw_reg_info *reg, char *pude_pl, void *priv) { @@ -4339,6 +4351,7 @@ static void mlxsw_sp_pude_event_func(const struct mlxsw_reg_info *reg, } else { netdev_info(mlxsw_sp_port->dev, "link down\n"); netif_carrier_off(mlxsw_sp_port->dev); + mlxsw_sp_port_down_wipe_counters(mlxsw_sp_port); } } -- 2.39.5