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Commit d6707bec authored by Petri Gynther's avatar Petri Gynther Committed by David S. Miller
Browse files

net: bcmgenet: rewrite bcmgenet_rx_refill() 



Currently, bcmgenet_desc_rx() calls bcmgenet_rx_refill() at the end of
Rx packet processing loop, after the current Rx packet has already been
passed to napi_gro_receive(). However, bcmgenet_rx_refill() might fail
to allocate a new Rx skb, thus leaving a hole on the Rx queue where no
valid Rx buffer exists.

To eliminate this situation:
1. Rewrite bcmgenet_rx_refill() to retain the current Rx skb on the Rx
   queue if a new replacement Rx skb can't be allocated and DMA-mapped.
   In this case, the data on the current Rx skb is effectively dropped.
2. Modify bcmgenet_desc_rx() to call bcmgenet_rx_refill() at the top of
   Rx packet processing loop, so that the new replacement Rx skb is
   already in place before the current Rx skb is processed.

Signed-off-by: default avatarPetri Gynther <pgynther@google.com>
Tested-by: default avatarJaedon Shin <jaedon.shin@gmail.com&gt;-->
Reviewed-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
Tested-by: default avatarFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 5e1459ca

drivers/net/ethernet/broadcom/genet/bcmgenet.c

+43 −56
Original line number Diff line number Diff line
@@ -1336,36 +1336,47 @@ static netdev_tx_t bcmgenet_xmit(struct sk_buff *skb, struct net_device *dev) 
	return ret;

}





static int bcmgenet_rx_refill(struct bcmgenet_priv *priv, struct enet_cb *cb)

static struct sk_buff *bcmgenet_rx_refill(struct bcmgenet_priv *priv,

					  struct enet_cb *cb)

{

	struct device *kdev = &priv->pdev->dev;

	struct sk_buff *skb;

	struct sk_buff *rx_skb;

	dma_addr_t mapping;

	int ret;



	/* Allocate a new Rx skb */

	skb = netdev_alloc_skb(priv->dev, priv->rx_buf_len + SKB_ALIGNMENT);

	if (!skb)

		return -ENOMEM;

	if (!skb) {

		priv->mib.alloc_rx_buff_failed++;

		netif_err(priv, rx_err, priv->dev,

			  "%s: Rx skb allocation failed\n", __func__);

		return NULL;

	}



	/* a caller did not release this control block */

	WARN_ON(cb->skb != NULL);

	cb->skb = skb;

	mapping = dma_map_single(kdev, skb->data,

				 priv->rx_buf_len, DMA_FROM_DEVICE);

	ret = dma_mapping_error(kdev, mapping);

	if (ret) {

	/* DMA-map the new Rx skb */

	mapping = dma_map_single(kdev, skb->data, priv->rx_buf_len,

				 DMA_FROM_DEVICE);

	if (dma_mapping_error(kdev, mapping)) {

		priv->mib.rx_dma_failed++;

		bcmgenet_free_cb(cb);

		dev_kfree_skb_any(skb);

		netif_err(priv, rx_err, priv->dev,

			  "%s DMA map failed\n", __func__);

		return ret;

			  "%s: Rx skb DMA mapping failed\n", __func__);

		return NULL;

	}



	/* Grab the current Rx skb from the ring and DMA-unmap it */

	rx_skb = cb->skb;

	if (likely(rx_skb))

		dma_unmap_single(kdev, dma_unmap_addr(cb, dma_addr),

				 priv->rx_buf_len, DMA_FROM_DEVICE);



	/* Put the new Rx skb on the ring */

	cb->skb = skb;

	dma_unmap_addr_set(cb, dma_addr, mapping);

	dmadesc_set_addr(priv, cb->bd_addr, mapping);



	return 0;

	/* Return the current Rx skb to caller */

	return rx_skb;

}



/* bcmgenet_desc_rx - descriptor based rx process.
@@ -1381,7 +1392,7 @@ static unsigned int bcmgenet_desc_rx(struct bcmgenet_priv *priv, 
	struct sk_buff *skb;

	u32 dma_length_status;

	unsigned long dma_flag;

	int len, err;

	int len;

	unsigned int rxpktprocessed = 0, rxpkttoprocess;

	unsigned int p_index;

	unsigned int discards;
@@ -1419,26 +1430,14 @@ static unsigned int bcmgenet_desc_rx(struct bcmgenet_priv *priv, 
	while ((rxpktprocessed < rxpkttoprocess) &&

	       (rxpktprocessed < budget)) {

		cb = &priv->rx_cbs[ring->read_ptr];

		skb = cb->skb;

		skb = bcmgenet_rx_refill(priv, cb);



		/* We do not have a backing SKB, so we do not have a

		 * corresponding DMA mapping for this incoming packet since

		 * bcmgenet_rx_refill always either has both skb and mapping or

		 * none.

		 */

		if (unlikely(!skb)) {

			dev->stats.rx_dropped++;

			dev->stats.rx_errors++;

			goto refill;

			goto next;

		}



		/* Unmap the packet contents such that we can use the

		 * RSV from the 64 bytes descriptor when enabled and save

		 * a 32-bits register read

		 */

		dma_unmap_single(&dev->dev, dma_unmap_addr(cb, dma_addr),

				 priv->rx_buf_len, DMA_FROM_DEVICE);



		if (!priv->desc_64b_en) {

			dma_length_status =

				dmadesc_get_length_status(priv, cb->bd_addr);
@@ -1465,10 +1464,10 @@ static unsigned int bcmgenet_desc_rx(struct bcmgenet_priv *priv, 
				  "dropping fragmented packet!\n");

			dev->stats.rx_dropped++;

			dev->stats.rx_errors++;

			dev_kfree_skb_any(cb->skb);

			cb->skb = NULL;

			goto refill;

			dev_kfree_skb_any(skb);

			goto next;

		}



		/* report errors */

		if (unlikely(dma_flag & (DMA_RX_CRC_ERROR |

						DMA_RX_OV |
@@ -1487,11 +1486,8 @@ static unsigned int bcmgenet_desc_rx(struct bcmgenet_priv *priv, 
				dev->stats.rx_length_errors++;

			dev->stats.rx_dropped++;

			dev->stats.rx_errors++;



			/* discard the packet and advance consumer index.*/

			dev_kfree_skb_any(cb->skb);

			cb->skb = NULL;

			goto refill;

			dev_kfree_skb_any(skb);

			goto next;

		} /* error packet */



		chksum_ok = (dma_flag & priv->dma_rx_chk_bit) &&
@@ -1524,17 +1520,9 @@ static unsigned int bcmgenet_desc_rx(struct bcmgenet_priv *priv, 


		/* Notify kernel */

		napi_gro_receive(&priv->napi, skb);

		cb->skb = NULL;

		netif_dbg(priv, rx_status, dev, "pushed up to kernel\n");



		/* refill RX path on the current control block */

refill:

		err = bcmgenet_rx_refill(priv, cb);

		if (err) {

			priv->mib.alloc_rx_buff_failed++;

			netif_err(priv, rx_err, dev, "Rx refill failed\n");

		}



next:

		rxpktprocessed++;

		if (likely(ring->read_ptr < ring->end_ptr))

			ring->read_ptr++;
@@ -1553,7 +1541,7 @@ static int bcmgenet_alloc_rx_buffers(struct bcmgenet_priv *priv, 
				     struct bcmgenet_rx_ring *ring)

{

	struct enet_cb *cb;

	int ret = 0;

	struct sk_buff *skb;

	int i;



	netif_dbg(priv, hw, priv->dev, "%s\n", __func__);
@@ -1561,15 +1549,14 @@ static int bcmgenet_alloc_rx_buffers(struct bcmgenet_priv *priv, 
	/* loop here for each buffer needing assign */

	for (i = 0; i < ring->size; i++) {

		cb = ring->cbs + i;

		if (cb->skb)

			continue;



		ret = bcmgenet_rx_refill(priv, cb);

		if (ret)

			break;

		skb = bcmgenet_rx_refill(priv, cb);

		if (skb)

			dev_kfree_skb_any(skb);

		if (!cb->skb)

			return -ENOMEM;

	}



	return ret;

	return 0;

}



static void bcmgenet_free_rx_buffers(struct bcmgenet_priv *priv)