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From: Yuval Shaia <yuval.shaia@oracle.com>
To: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc: davem@davemloft.net, tariqt@mellanox.com, netdev@vger.kernel.org,
	linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org,
	kernel-janitors@vger.kernel.org
Subject: Re: [PATCH] net/mlx4_en: Fix an error handling path in 'mlx4_en_init_netdev()'
Date: Thu, 10 May 2018 16:38:08 +0300	[thread overview]
Message-ID: <20180510133808.GA10943@lap1> (raw)
In-Reply-To: <20180510070226.19575-1-christophe.jaillet@wanadoo.fr>

On Thu, May 10, 2018 at 09:02:26AM +0200, 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.

Patch make sense but what's bothering me is that mlx4_en_free_resources
loops on the entire array, assuming !priv->tx_ring[t] means entry is
allocated but the existing code does not assume that, see [1]. So i looked
to see where tx_ring array is zeroed and didn't find it.

Am i missing something here.

> 
> 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>
> ---
>  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--) {

[1]

> -		kfree(priv->tx_ring[t]);
> -		kfree(priv->tx_cq[t]);
> -	}
>  out:
>  	mlx4_en_destroy_netdev(dev);
>  	return err;
> -- 
> 2.17.0
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

  reply	other threads:[~2018-05-10 13:38 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-10  7:02 Christophe JAILLET
2018-05-10 13:38 ` Yuval Shaia [this message]
2018-05-10 14:18   ` Dan Carpenter
2018-05-10 14:36     ` Tariq Toukan
2018-05-10 15:03       ` Tariq Toukan
2018-05-10 14:35   ` Christophe JAILLET
  -- strict thread matches above, loose matches on Subject: below --
2018-05-08  9:34 Christophe JAILLET
2018-05-09 10:31 ` Tariq Toukan

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