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Subject: Re: [PATCH v2] net/mlx4_en: Fix an error handling path in
 'mlx4_en_init_netdev()'
To:     Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        davem@davemloft.net, tariqt@mellanox.com
Cc:     netdev@vger.kernel.org, linux-rdma@vger.kernel.org,
        linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
References: <20180510070604.19635-1-christophe.jaillet@wanadoo.fr>
From:   Tariq Toukan <tariqt@mellanox.com>
Message-ID: <086ee1ec-3806-d1f4-78df-d3f4417e47f9@mellanox.com>
Date:   Thu, 10 May 2018 15:42:24 +0300
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On 10/05/2018 10:06 AM, Christophe JAILLET wrote:
> If an error occurs, 'mlx4_en_destroy_netdev()' is called.
> It then calls 'mlx4_en_free_resources()' which does the needed resources
> cleanup.
> 
> So, doing some explicit kfree in the error handling path would lead to
> some double kfree.
> 
> Simplify code to avoid such a case.
> 
> Fixes: 67f8b1dcb9ee ("net/mlx4_en: Refactor the XDP forwarding rings scheme")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> ---
> v1 -> v2 : rewrite the fix as explained by Tariq Toukan
>             (this 2nd version may have been posted twice, once without the
>             v2 tag. PLease ignore the first one)
> ---
> 
>   drivers/net/ethernet/mellanox/mlx4/en_netdev.c | 8 +-------
>   1 file changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> index e0adac4a9a19..9670b33fc9b1 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
> @@ -3324,12 +3324,11 @@ int mlx4_en_init_netdev(struct mlx4_en_dev *mdev, int port,
>   					   MAX_TX_RINGS, GFP_KERNEL);
>   		if (!priv->tx_ring[t]) {
>   			err = -ENOMEM;
> -			goto err_free_tx;
> +			goto out;
>   		}
>   		priv->tx_cq[t] = kzalloc(sizeof(struct mlx4_en_cq *) *
>   					 MAX_TX_RINGS, GFP_KERNEL);
>   		if (!priv->tx_cq[t]) {
> -			kfree(priv->tx_ring[t]);
>   			err = -ENOMEM;
>   			goto out;
>   		}
> @@ -3582,11 +3581,6 @@ int mlx4_en_init_netdev(struct mlx4_en_dev *mdev, int port,
>   
>   	return 0;
>   
> -err_free_tx:
> -	while (t--) {
> -		kfree(priv->tx_ring[t]);
> -		kfree(priv->tx_cq[t]);
> -	}
>   out:
>   	mlx4_en_destroy_netdev(dev);
>   	return err;
> 

Reviewed-by: Tariq Toukan <tariqt@mellanox.com>

Thanks Christophe.