Commit 8013d43a authored by Talat Batheesh's avatar Talat Batheesh Committed by Greg Kroah-Hartman

net/mlx5e: Fix fixpoint divide exception in mlx5e_am_stats_compare

[ Upstream commit e58edaa4 ]

Helmut reported a bug about division by zero while
running traffic and doing physical cable pull test.

When the cable unplugged the ppms become zero, so when
dividing the current ppms by the previous ppms in the
next dim iteration there is division by zero.

This patch prevent this division for both ppms and epms.

Fixes: c3164d2f ("net/mlx5e: Added BW check for DIM decision mechanism")
Reported-by: default avatarHelmut Grauer <helmut.grauer@de.ibm.com>
Signed-off-by: default avatarTalat Batheesh <talatb@mellanox.com>
Signed-off-by: default avatarSaeed Mahameed <saeedm@mellanox.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 538f9d93
......@@ -197,9 +197,15 @@ static int mlx5e_am_stats_compare(struct mlx5e_rx_am_stats *curr,
return (curr->bpms > prev->bpms) ? MLX5E_AM_STATS_BETTER :
MLX5E_AM_STATS_WORSE;
if (!prev->ppms)
return curr->ppms ? MLX5E_AM_STATS_BETTER :
MLX5E_AM_STATS_SAME;
if (IS_SIGNIFICANT_DIFF(curr->ppms, prev->ppms))
return (curr->ppms > prev->ppms) ? MLX5E_AM_STATS_BETTER :
MLX5E_AM_STATS_WORSE;
if (!prev->epms)
return MLX5E_AM_STATS_SAME;
if (IS_SIGNIFICANT_DIFF(curr->epms, prev->epms))
return (curr->epms < prev->epms) ? MLX5E_AM_STATS_BETTER :
......
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