Hello.
Mark Brown wrote:
Subject: 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 <[EMAIL PROTECTED]> for spotting the
issue, Mark Huth <[EMAIL PROTECTED]> for a simpler method and Simon
Blake <[EMAIL PROTECTED]> for testing resources.
Signed-Off-By: Mark Brown <[EMAIL PROTECTED]>
Index: linux-2.6/drivers/net/natsemi.c
===================================================================
--- linux-2.6.orig/drivers/net/natsemi.c 2007-03-11 02:32:43.000000000
+0000
+++ linux-2.6/drivers/net/natsemi.c 2007-03-13 00:12:29.000000000 +0000
[...]
@@ -2131,17 +2133,23 @@
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 (np->intr_status) {
+ 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);
+ if (netif_rx_schedule_prep(dev)) {
+ 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;
}
- return IRQ_HANDLED;
+
+ return IRQ_NONE;
}
The only "complaint" I have is that this "restructuring" seems
unnecessary: the only real change it does is an addition of else to the if
statement.
WBR, Sergei
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