netdev - [net 6/6] net/mlx5e: Fix division by 0 in mlx5e_select

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Date:   Tue, 12 Oct 2021 13:53:23 -0700
From:   Saeed Mahameed <saeed@...nel.org>
To:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, Tariq Toukan <tariqt@...dia.com>,
        Maxim Mikityanskiy <maximmi@...dia.com>,
        Saeed Mahameed <saeedm@...dia.com>
Subject: [net 6/6] net/mlx5e: Fix division by 0 in mlx5e_select_queue for representors

From: Maxim Mikityanskiy <maximmi@...dia.com>

Commit 846d6da1fcdb ("net/mlx5e: Fix division by 0 in
mlx5e_select_queue") makes mlx5e_build_nic_params assign a non-zero
initial value to priv->num_tc_x_num_ch, so that mlx5e_select_queue
doesn't fail with division by 0 if called before the first activation of
channels. However, the initialization flow of representors doesn't call
mlx5e_build_nic_params, so this bug can still happen with representors.

This commit fixes the bug by adding the missing assignment to
mlx5e_build_rep_params.

Fixes: 846d6da1fcdb ("net/mlx5e: Fix division by 0 in mlx5e_select_queue")
Signed-off-by: Maxim Mikityanskiy <maximmi@...dia.com>
Reviewed-by: Tariq Toukan <tariqt@...dia.com>
Signed-off-by: Saeed Mahameed <saeedm@...dia.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_rep.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c
index 0439203fc7d9..0684ac6699b2 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rep.c
@@ -618,6 +618,11 @@ static void mlx5e_build_rep_params(struct net_device *netdev)
 	params->mqprio.num_tc       = 1;
 	params->tunneled_offload_en = false;
 
+	/* 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->mqprio.num_tc;
+
 	mlx5_query_min_inline(mdev, &params->tx_min_inline_mode);
 }
 
-- 
2.31.1