net/mlx5e: Fix race in mlx5e_sw_stats and mlx5e_vport_stats
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: 9218b44d ("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>
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