1510d72863
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>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.