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cpmac: patch to reimplement rx ring with EOQ markers to avoid reset storms (closes #2569)

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SVN-Revision: 10585
This commit is contained in:
Matteo Croce 2008-03-11 00:59:11 +00:00
parent 001f82bf2c
commit 8988d03a8e
1 changed files with 178 additions and 0 deletions
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178
target/linux/ar7/patches-2.6.24/160-cpmac-rx-ring-use-eoq.diff Normal file
View file

@ -0,0 +1,178 @@
--- linux-2.6.24.3/drivers/net/cpmac.c.orig 2008-03-10 23:59:56.000000000 +0000
+++ linux-2.6.24.3/drivers/net/cpmac.c 2008-03-11 00:13:04.000000000 +0000
@@ -187,6 +187,7 @@
#define CPMAC_EOQ 0x1000
struct sk_buff *skb;
struct cpmac_desc *next;
+ struct cpmac_desc *prev;
dma_addr_t mapping;
dma_addr_t data_mapping;
};
@@ -242,6 +243,16 @@
printk("\n");
}
+static void cpmac_dump_all_desc(struct net_device *dev)
+{
+ struct cpmac_priv *priv = netdev_priv(dev);
+ struct cpmac_desc *dump = priv->rx_head;
+ do {
+ cpmac_dump_desc(dev, dump);
+ dump = dump->next;
+ } while (dump != priv->rx_head);
+}
+
static void cpmac_dump_skb(struct net_device *dev, struct sk_buff *skb)
{
int i;
@@ -413,21 +424,40 @@
static int cpmac_poll(struct napi_struct *napi, int budget)
{
struct sk_buff *skb;
- struct cpmac_desc *desc;
- int received = 0;
+ struct cpmac_desc *desc, *restart;
struct cpmac_priv *priv = container_of(napi, struct cpmac_priv, napi);
+ int received = 0, processed = 0;
spin_lock(&priv->rx_lock);
if (unlikely(!priv->rx_head)) {
if (netif_msg_rx_err(priv) && net_ratelimit())
printk(KERN_WARNING "%s: rx: polling, but no queue\n",
priv->dev->name);
+ spin_unlock(&priv->rx_lock);
netif_rx_complete(priv->dev, napi);
return 0;
}
desc = priv->rx_head;
+ restart = NULL;
while (((desc->dataflags & CPMAC_OWN) == 0) && (received < budget)) {
+ processed++;
+
+ if ((desc->dataflags & CPMAC_EOQ) != 0) {
+ /* The last update to eoq->hw_next didn't happen soon enough, and the
+ * receiver stopped here. Remember this descriptor so we can restart
+ * the receiver after freeing some space.
+ */
+ if (unlikely(restart)) {
+ if (netif_msg_rx_err(priv))
+ printk(KERN_ERR "%s: poll found a duplicate EOQ: %p and %p\n",
+ priv->dev->name, restart, desc);
+ goto fatal_error;
+ }
+
+ restart = desc->next;
+ }
+
skb = cpmac_rx_one(priv, desc);
if (likely(skb)) {
netif_receive_skb(skb);
@@ -436,19 +466,81 @@
desc = desc->next;
}
+ if (desc != priv->rx_head) {
+ /* We freed some buffers, but not the whole ring, add what we did free to the rx list */
+ desc->prev->hw_next = (u32)0;
+ priv->rx_head->prev->hw_next = priv->rx_head->mapping;
+ }
+
+ /* Optimization: If we did not actually process an EOQ (perhaps because of
+ * quota limits), check to see if the tail of the queue has EOQ set. We
+ * should immediately restart in that case so that the receiver can restart
+ * and run in parallel with more packet processing. This lets us handle slightly
+ * larger bursts before running out of ring space (assuming dev->weight < ring_size)
+ */
+ if (!restart &&
+ (priv->rx_head->prev->dataflags & (CPMAC_OWN|CPMAC_EOQ)) == CPMAC_EOQ &&
+ (priv->rx_head->dataflags & CPMAC_OWN) != 0) {
+ /* reset EOQ so the poll loop (above) doesn't try to restart this when it
+ * eventually gets to this descriptor.
+ */
+ priv->rx_head->prev->dataflags &= ~CPMAC_EOQ;
+ restart = priv->rx_head;
+ }
+
+ if (restart) {
+ priv->dev->stats.rx_errors++;
+ priv->dev->stats.rx_fifo_errors++;
+ if (netif_msg_rx_err(priv) && net_ratelimit())
+ printk(KERN_WARNING "%s: rx dma ring overrun\n", priv->dev->name);
+
+ if (unlikely((restart->dataflags & CPMAC_OWN) == 0)) {
+ if (netif_msg_drv(priv))
+ printk(KERN_ERR "%s: cpmac_poll is trying to restart rx from a descriptor that's not free: %p\n",
+ priv->dev->name, restart);
+ goto fatal_error;
+ }
+
+ cpmac_write(priv->regs, CPMAC_RX_PTR(0), restart->mapping);
+ }
+
priv->rx_head = desc;
spin_unlock(&priv->rx_lock);
if (unlikely(netif_msg_rx_status(priv)))
printk(KERN_DEBUG "%s: poll processed %d packets\n",
priv->dev->name, received);
- if (desc->dataflags & CPMAC_OWN) {
+ if (processed == 0) {
+ /* we ran out of packets to read, revert to interrupt-driven mode */
netif_rx_complete(priv->dev, napi);
- cpmac_write(priv->regs, CPMAC_RX_PTR(0), (u32)desc->mapping);
cpmac_write(priv->regs, CPMAC_RX_INT_ENABLE, 1);
return 0;
}
return 1;
+
+fatal_error:
+ /* Something went horribly wrong. Reset hardware to try to recover rather than wedging. */
+
+ if (netif_msg_drv(priv)) {
+ printk(KERN_ERR "%s: cpmac_poll is confused. Resetting hardware\n", priv->dev->name);
+ cpmac_dump_all_desc(priv->dev);
+ printk(KERN_DEBUG "%s: RX_PTR(0)=0x%08x RX_ACK(0)=0x%08x\n",
+ priv->dev->name,
+ cpmac_read(priv->regs, CPMAC_RX_PTR(0)),
+ cpmac_read(priv->regs, CPMAC_RX_ACK(0)));
+ }
+
+ spin_unlock(&priv->rx_lock);
+ netif_rx_complete(priv->dev, napi);
+ netif_stop_queue(priv->dev);
+ napi_disable(&priv->napi);
+
+ atomic_inc(&priv->reset_pending);
+ cpmac_hw_stop(priv->dev);
+ if (!schedule_work(&priv->reset_work))
+ atomic_dec(&priv->reset_pending);
+ return 0;
+
}
static int cpmac_start_xmit(struct sk_buff *skb, struct net_device *dev)
@@ -625,8 +717,10 @@
desc->dataflags = CPMAC_OWN;
dev->stats.rx_dropped++;
}
+ desc->hw_next = desc->next->mapping;
desc = desc->next;
}
+ priv->rx_head->prev->hw_next = 0;
}
static void cpmac_clear_tx(struct net_device *dev)
@@ -927,9 +1021,12 @@
desc->buflen = CPMAC_SKB_SIZE;
desc->dataflags = CPMAC_OWN;
desc->next = &priv->rx_head[(i + 1) % priv->ring_size];
+ desc->next->prev = desc;
desc->hw_next = (u32)desc->next->mapping;
}
+ priv->rx_head->prev->hw_next = (u32)0;
+
if ((res = request_irq(dev->irq, cpmac_irq, IRQF_SHARED,
dev->name, dev))) {
if (netif_msg_drv(priv))