forcedeth: Acknowledge only interrupts that are being processed

This is to avoid a race, accidentally acknowledging an interrupt that
we didn't notice and won't immediately process.  This is based solely
on code inspection; it is not known if there was an actual bug here.
Signed-off-by: David Decotigny <david.decotigny@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/nvidia/forcedeth.c

@@ -3398,7 +3398,8 @@ static irqreturn_t nv_nic_irq_tx(int foo, void *data)
 
 	for (i = 0;; i++) {
 		events = readl(base + NvRegMSIXIrqStatus) & NVREG_IRQ_TX_ALL;
-		writel(NVREG_IRQ_TX_ALL, base + NvRegMSIXIrqStatus);
+		writel(events, base + NvRegMSIXIrqStatus);
+		netdev_dbg(dev, "tx irq events: %08x\n", events);
 		if (!(events & np->irqmask))
 			break;
 
@@ -3509,7 +3510,8 @@ static irqreturn_t nv_nic_irq_rx(int foo, void *data)
 
 	for (i = 0;; i++) {
 		events = readl(base + NvRegMSIXIrqStatus) & NVREG_IRQ_RX_ALL;
-		writel(NVREG_IRQ_RX_ALL, base + NvRegMSIXIrqStatus);
+		writel(events, base + NvRegMSIXIrqStatus);
+		netdev_dbg(dev, "rx irq events: %08x\n", events);
 		if (!(events & np->irqmask))
 			break;
 
@@ -3553,7 +3555,8 @@ static irqreturn_t nv_nic_irq_other(int foo, void *data)
 
 	for (i = 0;; i++) {
 		events = readl(base + NvRegMSIXIrqStatus) & NVREG_IRQ_OTHER;
-		writel(NVREG_IRQ_OTHER, base + NvRegMSIXIrqStatus);
+		writel(events, base + NvRegMSIXIrqStatus);
+		netdev_dbg(dev, "irq events: %08x\n", events);
 		if (!(events & np->irqmask))
 			break;
 
@@ -3617,10 +3620,10 @@ static irqreturn_t nv_nic_irq_test(int foo, void *data)
 
 	if (!(np->msi_flags & NV_MSI_X_ENABLED)) {
 		events = readl(base + NvRegIrqStatus) & NVREG_IRQSTAT_MASK;
-		writel(NVREG_IRQ_TIMER, base + NvRegIrqStatus);
+		writel(events & NVREG_IRQ_TIMER, base + NvRegIrqStatus);
 	} else {
 		events = readl(base + NvRegMSIXIrqStatus) & NVREG_IRQSTAT_MASK;
-		writel(NVREG_IRQ_TIMER, base + NvRegMSIXIrqStatus);
+		writel(events & NVREG_IRQ_TIMER, base + NvRegMSIXIrqStatus);
 	}
 	pci_push(base);
 	if (!(events & NVREG_IRQ_TIMER))