Subject: Re: [PATCH] stmmac: fix init_dma_desc_rings() to handle errors

From: Bartlomiej Zolnierkiewicz <[email-masked]>
Date: Mon, 12 Aug 2013 11:36:55 +0200

On Friday, August 09, 2013 11:51:19 PM Denis Kirjanov wrote:
> On 8/9/13, Bartlomiej Zolnierkiewicz <[email-masked]> wrote:
> > In stmmac_init_rx_buffers():
> > * add missing handling of dma_map_single() error
> > * remove superfluous unlikely() optimization while at it
> >
> > Add stmmac_free_rx_buffers() helper and use it in dma_free_rx_skbufs().
> >
> > In init_dma_desc_rings():
> > * add missing handling of kmalloc_array() errors
> > * fix handling of dma_alloc_coherent() and stmmac_init_rx_buffers() errors
> > * make function return an error value on error and 0 on success
> >
> > In stmmac_open():
> > * add handling of init_dma_desc_rings() return value
> >
> > Signed-off-by: Bartlomiej Zolnierkiewicz <[email-masked]>
> > Signed-off-by: Kyungmin Park <[email-masked]>
> > ---
> >  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c |  111
> > ++++++++++++++++++----
> >  1 file changed, 92 insertions(+), 19 deletions(-)
> >
> > Index: b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> > ===================================================================
> > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c	2013-08-08
> > 14:36:44.000000000 +0200
> > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c	2013-08-08
> > 15:31:27.015438117 +0200
> > @@ -939,15 +939,20 @@ static int stmmac_init_rx_buffers(struct
> >
> >  	skb = __netdev_alloc_skb(priv->dev, priv->dma_buf_sz + NET_IP_ALIGN,
> >  				 GFP_KERNEL);
> > -	if (unlikely(skb == NULL)) {
> > +	if (!skb) {
> >  		pr_err("%s: Rx init fails; skb is NULL\n", __func__);
> > -		return 1;
> > +		return -ENOMEM;
> >  	}
> >  	skb_reserve(skb, NET_IP_ALIGN);
> >  	priv->rx_skbuff[i] = skb;
> >  	priv->rx_skbuff_dma[i] = dma_map_single(priv->device, skb->data,
> >  						priv->dma_buf_sz,
> >  						DMA_FROM_DEVICE);
> > +	if (dma_mapping_error(priv->device, priv->rx_skbuff_dma[i])) {
> > +		pr_err("%s: DMA mapping error\n", __func__);
> > +		dev_kfree_skb_any(skb);
> > +		return -EINVAL;
> > +	}
> 
> If dma fail here then you can crash in stmmac_free_rx_buffers()
> while touching priv->rx_skbuff[i]

Are you sure?

stmmac_free_rx_buffers() is not called for the current "i" but only
for the (fully initialized) past ones (please note "--i" in while loop
under err_init_rx_buffers label).

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

> >  	p->des2 = priv->rx_skbuff_dma[i];
> >
> > @@ -958,6 +963,16 @@ static int stmmac_init_rx_buffers(struct
> >  	return 0;
> >  }
> >
> > +static void stmmac_free_rx_buffers(struct stmmac_priv *priv, int i)
> > +{
> > +	if (priv->rx_skbuff[i]) {
> > +		dma_unmap_single(priv->device, priv->rx_skbuff_dma[i],
> > +				 priv->dma_buf_sz, DMA_FROM_DEVICE);
> > +		dev_kfree_skb_any(priv->rx_skbuff[i]);
> > +	}
> > +	priv->rx_skbuff[i] = NULL;
> > +}
> > +
> >  /**
> >   * init_dma_desc_rings - init the RX/TX descriptor rings
> >   * @dev: net device structure
> > @@ -965,13 +980,14 @@ static int stmmac_init_rx_buffers(struct
> >   * and allocates the socket buffers. It suppors the chained and ring
> >   * modes.
> >   */
> > -static void init_dma_desc_rings(struct net_device *dev)
> > +static int init_dma_desc_rings(struct net_device *dev)
> >  {
> >  	int i;
> >  	struct stmmac_priv *priv = netdev_priv(dev);
> >  	unsigned int txsize = priv->dma_tx_size;
> >  	unsigned int rxsize = priv->dma_rx_size;
> >  	unsigned int bfsize = 0;
> > +	int ret = -ENOMEM;
> >
> >  	/* Set the max buffer size according to the DESC mode
> >  	 * and the MTU. Note that RING mode allows 16KiB bsize.
> > @@ -992,34 +1008,60 @@ static void init_dma_desc_rings(struct n
> >  							  dma_extended_desc),
> >  						   &priv->dma_rx_phy,
> >  						   GFP_KERNEL);
> > +		if (!priv->dma_erx)
> > +			goto err_dma;
> > +
> >  		priv->dma_etx = dma_alloc_coherent(priv->device, txsize *
> >  						   sizeof(struct
> >  							  dma_extended_desc),
> >  						   &priv->dma_tx_phy,
> >  						   GFP_KERNEL);
> > -		if ((!priv->dma_erx) || (!priv->dma_etx))
> > -			return;
> > +		if (!priv->dma_etx) {
> > +			dma_free_coherent(priv->device, priv->dma_rx_size *
> > +					sizeof(struct dma_extended_desc),
> > +					priv->dma_erx, priv->dma_rx_phy);
> > +			goto err_dma;
> > +		}
> >  	} else {
> >  		priv->dma_rx = dma_alloc_coherent(priv->device, rxsize *
> >  						  sizeof(struct dma_desc),
> >  						  &priv->dma_rx_phy,
> >  						  GFP_KERNEL);
> > +		if (!priv->dma_rx)
> > +			goto err_dma;
> > +
> >  		priv->dma_tx = dma_alloc_coherent(priv->device, txsize *
> >  						  sizeof(struct dma_desc),
> >  						  &priv->dma_tx_phy,
> >  						  GFP_KERNEL);
> > -		if ((!priv->dma_rx) || (!priv->dma_tx))
> > -			return;
> > +		if (!priv->dma_tx) {
> > +			dma_free_coherent(priv->device, priv->dma_rx_size *
> > +					sizeof(struct dma_desc),
> > +					priv->dma_rx, priv->dma_rx_phy);
> > +			goto err_dma;
> > +		}
> >  	}
> >
> >  	priv->rx_skbuff_dma = kmalloc_array(rxsize, sizeof(dma_addr_t),
> >  					    GFP_KERNEL);
> > +	if (!priv->rx_skbuff_dma)
> > +		goto err_rx_skbuff_dma;
> > +
> >  	priv->rx_skbuff = kmalloc_array(rxsize, sizeof(struct sk_buff *),
> >  					GFP_KERNEL);
> > +	if (!priv->rx_skbuff)
> > +		goto err_rx_skbuff;
> > +
> >  	priv->tx_skbuff_dma = kmalloc_array(txsize, sizeof(dma_addr_t),
> >  					    GFP_KERNEL);
> > +	if (!priv->tx_skbuff_dma)
> > +		goto err_tx_skbuff_dma;
> > +
> >  	priv->tx_skbuff = kmalloc_array(txsize, sizeof(struct sk_buff *),
> >  					GFP_KERNEL);
> > +	if (!priv->tx_skbuff)
> > +		goto err_tx_skbuff;
> > +
> >  	if (netif_msg_probe(priv)) {
> >  		pr_debug("(%s) dma_rx_phy=0x%08x dma_tx_phy=0x%08x\n", __func__,
> >  			 (u32) priv->dma_rx_phy, (u32) priv->dma_tx_phy);
> > @@ -1034,8 +1076,9 @@ static void init_dma_desc_rings(struct n
> >  		else
> >  			p = priv->dma_rx + i;
> >
> > -		if (stmmac_init_rx_buffers(priv, p, i))
> > -			break;
> > +		ret = stmmac_init_rx_buffers(priv, p, i);
> > +		if (ret)
> > +			goto err_init_rx_buffers;
> >
> >  		if (netif_msg_probe(priv))
> >  			pr_debug("[%p]\t[%p]\t[%x]\n", priv->rx_skbuff[i],
> > @@ -1081,20 +1124,44 @@ static void init_dma_desc_rings(struct n
> >
> >  	if (netif_msg_hw(priv))
> >  		stmmac_display_rings(priv);
> > +
> > +	return 0;
> > +err_init_rx_buffers:
> > +	while (--i >= 0)
> > +		stmmac_free_rx_buffers(priv, i);
> > +	kfree(priv->tx_skbuff);
> > +err_tx_skbuff:
> > +	kfree(priv->tx_skbuff_dma);
> > +err_tx_skbuff_dma:
> > +	kfree(priv->rx_skbuff);
> > +err_rx_skbuff:
> > +	kfree(priv->rx_skbuff_dma);
> > +err_rx_skbuff_dma:
> > +	if (priv->extend_desc) {
> > +		dma_free_coherent(priv->device, priv->dma_tx_size *
> > +				  sizeof(struct dma_extended_desc),
> > +				  priv->dma_etx, priv->dma_tx_phy);
> > +		dma_free_coherent(priv->device, priv->dma_rx_size *
> > +				  sizeof(struct dma_extended_desc),
> > +				  priv->dma_erx, priv->dma_rx_phy);
> > +	} else {
> > +		dma_free_coherent(priv->device,
> > +				priv->dma_tx_size * sizeof(struct dma_desc),
> > +				priv->dma_tx, priv->dma_tx_phy);
> > +		dma_free_coherent(priv->device,
> > +				priv->dma_rx_size * sizeof(struct dma_desc),
> > +				priv->dma_rx, priv->dma_rx_phy);
> > +	}
> > +err_dma:
> > +	return ret;
> >  }
> >
> >  static void dma_free_rx_skbufs(struct stmmac_priv *priv)
> >  {
> >  	int i;
> >
> > -	for (i = 0; i < priv->dma_rx_size; i++) {
> > -		if (priv->rx_skbuff[i]) {
> > -			dma_unmap_single(priv->device, priv->rx_skbuff_dma[i],
> > -					 priv->dma_buf_sz, DMA_FROM_DEVICE);
> > -			dev_kfree_skb_any(priv->rx_skbuff[i]);
> > -		}
> > -		priv->rx_skbuff[i] = NULL;
> > -	}
> > +	for (i = 0; i < priv->dma_rx_size; i++)
> > +		stmmac_free_rx_buffers(priv, i);
> >  }
> >
> >  static void dma_free_tx_skbufs(struct stmmac_priv *priv)
> > @@ -1560,12 +1627,17 @@ static int stmmac_open(struct net_device
> >  	priv->dma_tx_size = STMMAC_ALIGN(dma_txsize);
> >  	priv->dma_rx_size = STMMAC_ALIGN(dma_rxsize);
> >  	priv->dma_buf_sz = STMMAC_ALIGN(buf_sz);
> > -	init_dma_desc_rings(dev);
> > +
> > +	ret = init_dma_desc_rings(dev);
> > +	if (ret < 0) {
> > +		pr_err("%s: DMA descriptors initialization failed\n", __func__);
> > +		goto dma_desc_error;
> > +	}
> >
> >  	/* DMA initialization and SW reset */
> >  	ret = stmmac_init_dma_engine(priv);
> >  	if (ret < 0) {
> > -		pr_err("%s: DMA initialization failed\n", __func__);
> > +		pr_err("%s: DMA engine initialization failed\n", __func__);
> >  		goto init_error;
> >  	}
> >
> > @@ -1672,6 +1744,7 @@ wolirq_error:
> >
> >  init_error:
> >  	free_dma_desc_resources(priv);
> > +dma_desc_error:
> >  	if (priv->phydev)
> >  		phy_disconnect(priv->phydev);
> >  phy_error:
> >
> > --
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