iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

via-rhine: forbid holes in the receive descriptor ring.

Browse Source 
Rationales:
- throttle work under memory pressure
- lower receive descriptor recycling latency for the network adapter
- lower the maintenance burden of uncommon paths

The patch is twofold:
- it fails early if the receive ring can't be completely initialized
  at dev->open() time
- it drops packets on the floor in the napi receive handler so as to
  keep the received ring full

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
françois romieu 2015-05-01 22:14:41 +02:00 committed by David S. Miller
parent 4d1fd9c1d8
commit 8709bb2c1e
1 changed files with 53 additions and 50 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

103
drivers/net/ethernet/via/via-rhine.c
View File

@ -473,7 +473,7 @@ struct rhine_private {
/* Frequently used values: keep some adjacent for cache effect. */
u32 quirks;
struct rx_desc *rx_head_desc;
unsigned int cur_rx, dirty_rx; /* Producer/consumer ring indices */
unsigned int cur_rx;
unsigned int cur_tx, dirty_tx;
unsigned int rx_buf_sz; /* Based on MTU+slack. */
struct rhine_stats rx_stats;
@ -1239,6 +1239,17 @@ static inline int rhine_skb_dma_init(struct net_device *dev,
return 0;
}
static void rhine_reset_rbufs(struct rhine_private *rp)
{
int i;
rp->cur_rx = 0;
rp->rx_head_desc = rp->rx_ring;
for (i = 0; i < RX_RING_SIZE; i++)
rp->rx_ring[i].rx_status = cpu_to_le32(DescOwn);
}
static inline void rhine_skb_dma_nic_store(struct rhine_private *rp,
struct rhine_skb_dma *sd, int entry)
{
@ -1249,16 +1260,15 @@ static inline void rhine_skb_dma_nic_store(struct rhine_private *rp,
dma_wmb();
}
static void alloc_rbufs(struct net_device *dev)
static void free_rbufs(struct net_device* dev);
static int alloc_rbufs(struct net_device *dev)
{
struct rhine_private *rp = netdev_priv(dev);
dma_addr_t next;
int rc, i;
rp->dirty_rx = rp->cur_rx = 0;
rp->rx_buf_sz = (dev->mtu <= 1500 ? PKT_BUF_SZ : dev->mtu + 32);
rp->rx_head_desc = &rp->rx_ring[0];
next = rp->rx_ring_dma;
/* Init the ring entries */
@ -1277,14 +1287,17 @@ static void alloc_rbufs(struct net_device *dev)
struct rhine_skb_dma sd;
rc = rhine_skb_dma_init(dev, &sd);
if (rc < 0)
break;
if (rc < 0) {
free_rbufs(dev);
goto out;
}
rhine_skb_dma_nic_store(rp, &sd, i);
rp->rx_ring[i].rx_status = cpu_to_le32(DescOwn);
}
rp->dirty_rx = (unsigned int)(i - RX_RING_SIZE);
rhine_reset_rbufs(rp);
out:
return rc;
}
static void free_rbufs(struct net_device* dev)
@ -1696,7 +1709,10 @@ static int rhine_open(struct net_device *dev)
if (rc < 0)
goto out_free_irq;
alloc_rbufs(dev);
rc = alloc_rbufs(dev);
if (rc < 0)
goto out_free_ring;
alloc_tbufs(dev);
rhine_chip_reset(dev);
rhine_task_enable(rp);
@ -1711,6 +1727,8 @@ static int rhine_open(struct net_device *dev)
out:
return rc;
out_free_ring:
free_ring(dev);
out_free_irq:
free_irq(rp->irq, dev);
goto out;
@ -1733,9 +1751,9 @@ static void rhine_reset_task(struct work_struct *work)
/* clear all descriptors */
free_tbufs(dev);
free_rbufs(dev);
alloc_tbufs(dev);
alloc_rbufs(dev);
rhine_reset_rbufs(rp);
/* Reinitialize the hardware. */
rhine_chip_reset(dev);
@ -2033,16 +2051,18 @@ static int rhine_rx(struct net_device *dev, int limit)
}
}
} else {
struct sk_buff *skb = NULL;
/* Length should omit the CRC */
int pkt_len = data_size - 4;
struct sk_buff *skb;
u16 vlan_tci = 0;
/* Check if the packet is long enough to accept without
copying to a minimally-sized skbuff. */
if (pkt_len < rx_copybreak)
if (pkt_len < rx_copybreak) {
skb = netdev_alloc_skb_ip_align(dev, pkt_len);
if (skb) {
if (unlikely(!skb))
goto drop;
dma_sync_single_for_cpu(hwdev,
rp->rx_skbuff_dma[entry],
rp->rx_buf_sz,
@ -2051,25 +2071,28 @@ static int rhine_rx(struct net_device *dev, int limit)
skb_copy_to_linear_data(skb,
rp->rx_skbuff[entry]->data,
pkt_len);
skb_put(skb, pkt_len);
dma_sync_single_for_device(hwdev,
rp->rx_skbuff_dma[entry],
rp->rx_buf_sz,
DMA_FROM_DEVICE);
} else {
struct rhine_skb_dma sd;
if (unlikely(rhine_skb_dma_init(dev, &sd) < 0))
goto drop;
skb = rp->rx_skbuff[entry];
if (skb == NULL) {
netdev_err(dev, "Inconsistent Rx descriptor chain\n");
break;
}
rp->rx_skbuff[entry] = NULL;
skb_put(skb, pkt_len);
dma_unmap_single(hwdev,
rp->rx_skbuff_dma[entry],
rp->rx_buf_sz,
DMA_FROM_DEVICE);
rhine_skb_dma_nic_store(rp, &sd, entry);
}
skb_put(skb, pkt_len);
if (unlikely(desc_length & DescTag))
vlan_tci = rhine_get_vlan_tci(skb, data_size);
@ -2084,36 +2107,17 @@ static int rhine_rx(struct net_device *dev, int limit)
rp->rx_stats.packets++;
u64_stats_update_end(&rp->rx_stats.syncp);
}
give_descriptor_to_nic:
desc->rx_status = cpu_to_le32(DescOwn);
entry = (++rp->cur_rx) % RX_RING_SIZE;
rp->rx_head_desc = &rp->rx_ring[entry];
}
/* Refill the Rx ring buffers. */
for (; rp->cur_rx - rp->dirty_rx > 0; rp->dirty_rx++) {
struct sk_buff *skb;
entry = rp->dirty_rx % RX_RING_SIZE;
if (rp->rx_skbuff[entry] == NULL) {
skb = netdev_alloc_skb(dev, rp->rx_buf_sz);
rp->rx_skbuff[entry] = skb;
if (skb == NULL)
break; /* Better luck next round. */
rp->rx_skbuff_dma[entry] =
dma_map_single(hwdev, skb->data,
rp->rx_buf_sz,
DMA_FROM_DEVICE);
if (dma_mapping_error(hwdev,
rp->rx_skbuff_dma[entry])) {
dev_kfree_skb(skb);
rp->rx_skbuff_dma[entry] = 0;
break;
}
rp->rx_ring[entry].addr = cpu_to_le32(rp->rx_skbuff_dma[entry]);
dma_wmb();
}
rp->rx_ring[entry].rx_status = cpu_to_le32(DescOwn);
}
return count;
drop:
dev->stats.rx_dropped++;
goto give_descriptor_to_nic;
}
static void rhine_restart_tx(struct net_device *dev) {
@ -2518,9 +2522,8 @@ static int rhine_resume(struct device *device)
enable_mmio(rp->pioaddr, rp->quirks);
rhine_power_init(dev);
free_tbufs(dev);
free_rbufs(dev);
alloc_tbufs(dev);
alloc_rbufs(dev);
rhine_reset_rbufs(rp);
rhine_task_enable(rp);
spin_lock_bh(&rp->lock);
init_registers(dev);