Re: [PATCH] net/ftgmac100: fix ring allocation unwind leaks on open failure

[Andrew Lunn]

On Sat, Mar 28, 2026 at 05:24:28PM +0800, Yufan Chen wrote:
> From: Yufan Chen <ericterminal@xxxxxxxxx>
> 
> ftgmac100_alloc_rings() allocated rx_skbs, tx_skbs, rxdes, txdes, and rx_scratch in stages but returned directly on any intermediate allocation failure. This left previously allocated objects unreleased and could accumulate leaks across repeated ifup retries under memory pressure.

Please take a read of

https://docs.kernel.org/process/submitting-patches.html

and

https://www.kernel.org/doc/html/latest/process/maintainer-netdev.html


You have a number of process issues.

>  static int ftgmac100_alloc_rings(struct ftgmac100 *priv)
>  {
> +	int err = -ENOMEM;
> +
>  	/* Allocate skb arrays */
>  	priv->rx_skbs = kcalloc(MAX_RX_QUEUE_ENTRIES, sizeof(void *),
>  				GFP_KERNEL);
>  	if (!priv->rx_skbs)
> -		return -ENOMEM;
> +		goto out;
>  	priv->tx_skbs = kcalloc(MAX_TX_QUEUE_ENTRIES, sizeof(void *),
>  				GFP_KERNEL);
>  	if (!priv->tx_skbs)
> -		return -ENOMEM;
> +		goto out;
>  
>  	/* Allocate descriptors */
>  	priv->rxdes = dma_alloc_coherent(priv->dev,
>  					 MAX_RX_QUEUE_ENTRIES * sizeof(struct ftgmac100_rxdes),
>  					 &priv->rxdes_dma, GFP_KERNEL);
>  	if (!priv->rxdes)
> -		return -ENOMEM;
> +		goto out;
>  	priv->txdes = dma_alloc_coherent(priv->dev,
>  					 MAX_TX_QUEUE_ENTRIES * sizeof(struct ftgmac100_txdes),
>  					 &priv->txdes_dma, GFP_KERNEL);
>  	if (!priv->txdes)
> -		return -ENOMEM;
> +		goto out;
>  
>  	/* Allocate scratch packet buffer */
>  	priv->rx_scratch = dma_alloc_coherent(priv->dev,
> @@ -997,9 +1002,13 @@ static int ftgmac100_alloc_rings(struct ftgmac100 *priv)
>  					      &priv->rx_scratch_dma,
>  					      GFP_KERNEL);
>  	if (!priv->rx_scratch)
> -		return -ENOMEM;
> +		goto out;
>  
>  	return 0;
> +
> +out:
> +	ftgmac100_free_rings(priv);
> +	return err;

If you look at other drivers, you will notice that functions that do
allocations pretty much always do their own cleanup, rather than
calling a helper. You generally see multiple labels, one per
allocation, and gotos jumping to the needed code.

    Andrew

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