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authorbroonie@sirena.org.uk <broonie@sirena.org.uk>2007-03-14 19:49:14 +0000
committerJeff Garzik <jeff@garzik.org>2007-03-15 10:59:54 -0400
commit069f8256362b7a17da532f0631cee73b4cfee65b (patch)
treeee8e9e4a3b78de04e15a71a4b4216bfc050b3a8a
parent14fdd90ef2ec1878d6851ec4dd8d5abb2cef098c (diff)
downloadlwn-069f8256362b7a17da532f0631cee73b4cfee65b.tar.gz
lwn-069f8256362b7a17da532f0631cee73b4cfee65b.zip
natsemi: Fix NAPI for interrupt sharing
The interrupt status register for the natsemi chips is clear on read and was read unconditionally from both the interrupt and from the NAPI poll routine, meaning that if the interrupt service routine was called (for example, due to a shared interrupt) while a NAPI poll was scheduled interrupts could be missed. This patch fixes that by ensuring that the interrupt status register is only read by the interrupt handler when interrupts are enabled from the chip. It also reverts a workaround for this problem from the netpoll hook and improves the trace for interrupt events. Thanks to Sergei Shtylyov <sshtylyov@ru.mvista.com> for spotting the issue, Mark Huth <mhuth@mvista.com> for a simpler method and Simon Blake <simon@citylink.co.nz> for testing resources. Signed-Off-By: Mark Brown <broonie@sirena.org.uk> Signed-off-by: Jeff Garzik <jeff@garzik.org>
-rw-r--r--drivers/net/natsemi.c38
1 files changed, 20 insertions, 18 deletions
diff --git a/drivers/net/natsemi.c b/drivers/net/natsemi.c
index 2888880df3b7..5f88200724e6 100644
--- a/drivers/net/natsemi.c
+++ b/drivers/net/natsemi.c
@@ -2119,28 +2119,35 @@ static irqreturn_t intr_handler(int irq, void *dev_instance)
struct netdev_private *np = netdev_priv(dev);
void __iomem * ioaddr = ns_ioaddr(dev);
- if (np->hands_off)
+ /* Reading IntrStatus automatically acknowledges so don't do
+ * that while interrupts are disabled, (for example, while a
+ * poll is scheduled). */
+ if (np->hands_off || !readl(ioaddr + IntrEnable))
return IRQ_NONE;
- /* Reading automatically acknowledges. */
np->intr_status = readl(ioaddr + IntrStatus);
+ if (!np->intr_status)
+ return IRQ_NONE;
+
if (netif_msg_intr(np))
printk(KERN_DEBUG
"%s: Interrupt, status %#08x, mask %#08x.\n",
dev->name, np->intr_status,
readl(ioaddr + IntrMask));
- if (!np->intr_status)
- return IRQ_NONE;
-
prefetch(&np->rx_skbuff[np->cur_rx % RX_RING_SIZE]);
if (netif_rx_schedule_prep(dev)) {
/* Disable interrupts and register for poll */
natsemi_irq_disable(dev);
__netif_rx_schedule(dev);
- }
+ } else
+ printk(KERN_WARNING
+ "%s: Ignoring interrupt, status %#08x, mask %#08x.\n",
+ dev->name, np->intr_status,
+ readl(ioaddr + IntrMask));
+
return IRQ_HANDLED;
}
@@ -2156,6 +2163,12 @@ static int natsemi_poll(struct net_device *dev, int *budget)
int work_done = 0;
do {
+ if (netif_msg_intr(np))
+ printk(KERN_DEBUG
+ "%s: Poll, status %#08x, mask %#08x.\n",
+ dev->name, np->intr_status,
+ readl(ioaddr + IntrMask));
+
if (np->intr_status &
(IntrTxDone | IntrTxIntr | IntrTxIdle | IntrTxErr)) {
spin_lock(&np->lock);
@@ -2399,19 +2412,8 @@ static struct net_device_stats *get_stats(struct net_device *dev)
#ifdef CONFIG_NET_POLL_CONTROLLER
static void natsemi_poll_controller(struct net_device *dev)
{
- struct netdev_private *np = netdev_priv(dev);
-
disable_irq(dev->irq);
-
- /*
- * A real interrupt might have already reached us at this point
- * but NAPI might still haven't called us back. As the interrupt
- * status register is cleared by reading, we should prevent an
- * interrupt loss in this case...
- */
- if (!np->intr_status)
- intr_handler(dev->irq, dev);
-
+ intr_handler(dev->irq, dev);
enable_irq(dev->irq);
}
#endif