cpmac: patch to reimplement rx ring with EOQ markers to avoid reset storms (closes #2569)
SVN-Revision: 10585
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1 changed files with 178 additions and 0 deletions
178
target/linux/ar7/patches-2.6.24/160-cpmac-rx-ring-use-eoq.diff
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178
target/linux/ar7/patches-2.6.24/160-cpmac-rx-ring-use-eoq.diff
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@ -0,0 +1,178 @@
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--- linux-2.6.24.3/drivers/net/cpmac.c.orig 2008-03-10 23:59:56.000000000 +0000
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+++ linux-2.6.24.3/drivers/net/cpmac.c 2008-03-11 00:13:04.000000000 +0000
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@@ -187,6 +187,7 @@
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#define CPMAC_EOQ 0x1000
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struct sk_buff *skb;
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struct cpmac_desc *next;
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+ struct cpmac_desc *prev;
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dma_addr_t mapping;
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dma_addr_t data_mapping;
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};
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@@ -242,6 +243,16 @@
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printk("\n");
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}
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+static void cpmac_dump_all_desc(struct net_device *dev)
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+{
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+ struct cpmac_priv *priv = netdev_priv(dev);
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+ struct cpmac_desc *dump = priv->rx_head;
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+ do {
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+ cpmac_dump_desc(dev, dump);
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+ dump = dump->next;
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+ } while (dump != priv->rx_head);
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+}
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+
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static void cpmac_dump_skb(struct net_device *dev, struct sk_buff *skb)
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{
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int i;
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@@ -413,21 +424,40 @@
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static int cpmac_poll(struct napi_struct *napi, int budget)
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{
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struct sk_buff *skb;
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- struct cpmac_desc *desc;
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- int received = 0;
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+ struct cpmac_desc *desc, *restart;
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struct cpmac_priv *priv = container_of(napi, struct cpmac_priv, napi);
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+ int received = 0, processed = 0;
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spin_lock(&priv->rx_lock);
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if (unlikely(!priv->rx_head)) {
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if (netif_msg_rx_err(priv) && net_ratelimit())
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printk(KERN_WARNING "%s: rx: polling, but no queue\n",
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priv->dev->name);
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+ spin_unlock(&priv->rx_lock);
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netif_rx_complete(priv->dev, napi);
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return 0;
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}
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desc = priv->rx_head;
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+ restart = NULL;
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while (((desc->dataflags & CPMAC_OWN) == 0) && (received < budget)) {
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+ processed++;
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+
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+ if ((desc->dataflags & CPMAC_EOQ) != 0) {
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+ /* The last update to eoq->hw_next didn't happen soon enough, and the
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+ * receiver stopped here. Remember this descriptor so we can restart
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+ * the receiver after freeing some space.
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+ */
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+ if (unlikely(restart)) {
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+ if (netif_msg_rx_err(priv))
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+ printk(KERN_ERR "%s: poll found a duplicate EOQ: %p and %p\n",
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+ priv->dev->name, restart, desc);
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+ goto fatal_error;
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+ }
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+
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+ restart = desc->next;
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+ }
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+
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skb = cpmac_rx_one(priv, desc);
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if (likely(skb)) {
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netif_receive_skb(skb);
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@@ -436,19 +466,81 @@
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desc = desc->next;
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}
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+ if (desc != priv->rx_head) {
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+ /* We freed some buffers, but not the whole ring, add what we did free to the rx list */
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+ desc->prev->hw_next = (u32)0;
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+ priv->rx_head->prev->hw_next = priv->rx_head->mapping;
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+ }
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+
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+ /* Optimization: If we did not actually process an EOQ (perhaps because of
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+ * quota limits), check to see if the tail of the queue has EOQ set. We
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+ * should immediately restart in that case so that the receiver can restart
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+ * and run in parallel with more packet processing. This lets us handle slightly
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+ * larger bursts before running out of ring space (assuming dev->weight < ring_size)
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+ */
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+ if (!restart &&
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+ (priv->rx_head->prev->dataflags & (CPMAC_OWN|CPMAC_EOQ)) == CPMAC_EOQ &&
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+ (priv->rx_head->dataflags & CPMAC_OWN) != 0) {
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+ /* reset EOQ so the poll loop (above) doesn't try to restart this when it
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+ * eventually gets to this descriptor.
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+ */
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+ priv->rx_head->prev->dataflags &= ~CPMAC_EOQ;
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+ restart = priv->rx_head;
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+ }
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+
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+ if (restart) {
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+ priv->dev->stats.rx_errors++;
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+ priv->dev->stats.rx_fifo_errors++;
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+ if (netif_msg_rx_err(priv) && net_ratelimit())
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+ printk(KERN_WARNING "%s: rx dma ring overrun\n", priv->dev->name);
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+
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+ if (unlikely((restart->dataflags & CPMAC_OWN) == 0)) {
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+ if (netif_msg_drv(priv))
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+ printk(KERN_ERR "%s: cpmac_poll is trying to restart rx from a descriptor that's not free: %p\n",
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+ priv->dev->name, restart);
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+ goto fatal_error;
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+ }
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+
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+ cpmac_write(priv->regs, CPMAC_RX_PTR(0), restart->mapping);
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+ }
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+
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priv->rx_head = desc;
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spin_unlock(&priv->rx_lock);
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if (unlikely(netif_msg_rx_status(priv)))
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printk(KERN_DEBUG "%s: poll processed %d packets\n",
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priv->dev->name, received);
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- if (desc->dataflags & CPMAC_OWN) {
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+ if (processed == 0) {
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+ /* we ran out of packets to read, revert to interrupt-driven mode */
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netif_rx_complete(priv->dev, napi);
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- cpmac_write(priv->regs, CPMAC_RX_PTR(0), (u32)desc->mapping);
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cpmac_write(priv->regs, CPMAC_RX_INT_ENABLE, 1);
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return 0;
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}
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return 1;
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+
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+fatal_error:
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+ /* Something went horribly wrong. Reset hardware to try to recover rather than wedging. */
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+
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+ if (netif_msg_drv(priv)) {
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+ printk(KERN_ERR "%s: cpmac_poll is confused. Resetting hardware\n", priv->dev->name);
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+ cpmac_dump_all_desc(priv->dev);
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+ printk(KERN_DEBUG "%s: RX_PTR(0)=0x%08x RX_ACK(0)=0x%08x\n",
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+ priv->dev->name,
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+ cpmac_read(priv->regs, CPMAC_RX_PTR(0)),
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+ cpmac_read(priv->regs, CPMAC_RX_ACK(0)));
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+ }
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+
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+ spin_unlock(&priv->rx_lock);
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+ netif_rx_complete(priv->dev, napi);
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+ netif_stop_queue(priv->dev);
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+ napi_disable(&priv->napi);
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+
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+ atomic_inc(&priv->reset_pending);
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+ cpmac_hw_stop(priv->dev);
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+ if (!schedule_work(&priv->reset_work))
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+ atomic_dec(&priv->reset_pending);
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+ return 0;
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+
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}
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static int cpmac_start_xmit(struct sk_buff *skb, struct net_device *dev)
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@@ -625,8 +717,10 @@
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desc->dataflags = CPMAC_OWN;
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dev->stats.rx_dropped++;
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}
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+ desc->hw_next = desc->next->mapping;
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desc = desc->next;
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}
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+ priv->rx_head->prev->hw_next = 0;
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}
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static void cpmac_clear_tx(struct net_device *dev)
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@@ -927,9 +1021,12 @@
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desc->buflen = CPMAC_SKB_SIZE;
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desc->dataflags = CPMAC_OWN;
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desc->next = &priv->rx_head[(i + 1) % priv->ring_size];
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+ desc->next->prev = desc;
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desc->hw_next = (u32)desc->next->mapping;
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}
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+ priv->rx_head->prev->hw_next = (u32)0;
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+
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if ((res = request_irq(dev->irq, cpmac_irq, IRQF_SHARED,
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dev->name, dev))) {
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if (netif_msg_drv(priv))
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