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Message-Id: <13029e01c3888b592c86544f61cd22ac7e1059b2.1428340371.git.romieu@fr.zoreil.com>
Date: Mon, 6 Apr 2015 20:01:52 +0200
From: Francois Romieu <romieu@...zoreil.com>
To: netdev@...r.kernel.org
Cc: "Nix" <nix@...eri.org.uk>, "David S. Miller" <davem@...emloft.net>,
rl@...lgate.ch, "Bjarke Istrup Pedersen" <gurligebis@...too.org>
Subject: [PATCH net-next 4/4] via-rhine: forbid holes in the receive descriptor ring.
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:
1. it fails early if the receive buffer ring can't be completely
initialized at dev->open() time
2. it drops packets on the floor in the napi receive handler so as to
keep the ring full.
Signed-off-by: Francois Romieu <romieu@...zoreil.com>
---
drivers/net/ethernet/via/via-rhine.c | 101 ++++++++++++++++++-----------------
1 file changed, 52 insertions(+), 49 deletions(-)
diff --git a/drivers/net/ethernet/via/via-rhine.c b/drivers/net/ethernet/via/via-rhine.c
index ae1ab6b..94729b1 100644
--- a/drivers/net/ethernet/via/via-rhine.c
+++ b/drivers/net/ethernet/via/via-rhine.c
@@ -471,7 +471,7 @@ 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;
@@ -1237,6 +1237,16 @@ 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;
+
+ 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)
{
@@ -1247,14 +1257,14 @@ static inline void rhine_skb_dma_nic_store(struct rhine_private *rp,
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;
@@ -1275,14 +1285,17 @@ 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)
@@ -1692,7 +1705,10 @@ 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);
@@ -1707,6 +1723,8 @@ 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;
@@ -1729,9 +1747,9 @@ 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);
@@ -2021,16 +2039,18 @@ 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,
@@ -2039,25 +2059,28 @@ 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);
@@ -2072,36 +2095,17 @@ 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:
+ rp->rx_ring[entry].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]);
- 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) {
@@ -2506,9 +2510,8 @@ 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);
--
2.1.0
--
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