From c912b0fa9788f442d1566a02c6257ca32157b964 Mon Sep 17 00:00:00 2001 From: Maxim Mikityanskiy Date: Mon, 1 Mar 2021 20:59:59 +0200 Subject: [PATCH] net/mlx5e: Fix division by 0 in mlx5e_select_queue mlx5e_select_queue compares num_tc_x_num_ch to real_num_tx_queues to determine if HTB and/or PTP offloads are active. If they are, it calculates netdev_pick_tx() % num_tc_x_num_ch to prevent it from selecting HTB and PTP queues for regular traffic. However, before the channels are first activated, num_tc_x_num_ch is zero. If ndo_select_queue gets called at this point, the HTB/PTP check will pass, and mlx5e_select_queue will attempt to take a modulo by num_tc_x_num_ch, which equals to zero. This commit fixes the bug by assigning num_tc_x_num_ch to a non-zero value before registering the netdev. Fixes: 63f9d5b33580 ("net/mlx5e: Support HTB offload") Reported-by: Jesper Dangaard Brouer Signed-off-by: Maxim Mikityanskiy Reviewed-by: Tariq Toukan Signed-off-by: Saeed Mahameed --- drivers/net/ethernet/mellanox/mlx5/core/en_main.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c index c8b8249846a98..158f947a85031 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c @@ -4979,6 +4979,11 @@ void mlx5e_build_nic_params(struct mlx5e_priv *priv, struct mlx5e_xsk *xsk, u16 priv->max_nch); params->num_tc = 1; + /* Set an initial non-zero value, so that mlx5e_select_queue won't + * divide by zero if called before first activating channels. + */ + priv->num_tc_x_num_ch = params->num_channels * params->num_tc; + /* SQ */ params->log_sq_size = is_kdump_kernel() ? MLX5E_PARAMS_MINIMUM_LOG_SQ_SIZE : -- 2.39.5