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net: bcmgenet: rewrite bcmgenet_rx_refill()

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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: Petri Gynther <pgynther@google.com>
Tested-by: Jaedon Shin <jaedon.shin@gmail.com>--
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Petri Gynther 2015-03-12 15:48:00 -07:00 committed by David S. Miller
parent 5e1459ca13
commit d6707bec59
1 changed files with 45 additions and 58 deletions
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103
drivers/net/ethernet/broadcom/genet/bcmgenet.c
View file

@ -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;
/* 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) {
priv->mib.rx_dma_failed++;
bcmgenet_free_cb(cb);
if (!skb) {
priv->mib.alloc_rx_buff_failed++;
netif_err(priv, rx_err, priv->dev,
"%s DMA map failed\n", __func__);
return ret;
"%s: Rx skb allocation failed\n", __func__);
return NULL;
}
/* 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++;
dev_kfree_skb_any(skb);
netif_err(priv, rx_err, priv->dev,
"%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)