We have observed a sudden spike in rx/tx_packets and rx/tx_bytes
reported under /proc/net/dev. There is a race in mlx5e_update_stats()
and some of the get-stats functions (the one that we hit is the
mlx5e_get_stats() which is called by ndo_get_stats64()).
In particular, the very first thing mlx5e_update_sw_counters()
does is 'memset(s, 0, sizeof(*s))'. For example, if mlx5e_get_stats()
is unlucky at one point, rx_bytes and rx_packets could be 0. One second
later, a normal (and much bigger than 0) value will be reported.
This patch is to use a 'struct mlx5e_sw_stats temp' to avoid
a direct memset zero on priv->stats.sw.
mlx5e_update_vport_counters() has a similar race. Hence, addressed
together. However, memset zero is removed instead because
it is not needed.
I am lucky enough to catch this 0-reset in rx multicast:
eth0:
41457665 76804 70 0 0 70 0 47085
15586634 87502 3 0 0 0 3 0
eth0:
41459860 76815 70 0 0 70 0 47094
15588376 87516 3 0 0 0 3 0
eth0:
41460577 76822 70 0 0 70 0 0
15589083 87521 3 0 0 0 3 0
eth0:
41463293 76838 70 0 0 70 0 47108
15595872 87538 3 0 0 0 3 0
eth0:
41463379 76839 70 0 0 70 0 47116
15596138 87539 3 0 0 0 3 0
v2: Remove memset zero from mlx5e_update_vport_counters()
v1: Use temp and memcpy
Fixes: 9218b44dcc05 ("net/mlx5e: Statistics handling refactoring")
Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Suggested-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
static void mlx5e_update_sw_counters(struct mlx5e_priv *priv)
{
static void mlx5e_update_sw_counters(struct mlx5e_priv *priv)
{
- struct mlx5e_sw_stats *s = &priv->stats.sw;
+ struct mlx5e_sw_stats temp, *s = &temp;
struct mlx5e_rq_stats *rq_stats;
struct mlx5e_sq_stats *sq_stats;
u64 tx_offload_none = 0;
struct mlx5e_rq_stats *rq_stats;
struct mlx5e_sq_stats *sq_stats;
u64 tx_offload_none = 0;
s->link_down_events_phy = MLX5_GET(ppcnt_reg,
priv->stats.pport.phy_counters,
counter_set.phys_layer_cntrs.link_down_events);
s->link_down_events_phy = MLX5_GET(ppcnt_reg,
priv->stats.pport.phy_counters,
counter_set.phys_layer_cntrs.link_down_events);
+ memcpy(&priv->stats.sw, s, sizeof(*s));
}
static void mlx5e_update_vport_counters(struct mlx5e_priv *priv)
}
static void mlx5e_update_vport_counters(struct mlx5e_priv *priv)
MLX5_SET(query_vport_counter_in, in, op_mod, 0);
MLX5_SET(query_vport_counter_in, in, other_vport, 0);
MLX5_SET(query_vport_counter_in, in, op_mod, 0);
MLX5_SET(query_vport_counter_in, in, other_vport, 0);
- memset(out, 0, outlen);
mlx5_cmd_exec(mdev, in, sizeof(in), out, outlen);
}
mlx5_cmd_exec(mdev, in, sizeof(in), out, outlen);
}