[RFC Patch V2 07/16] x86, irq, ACPI: protect acpi_pci_irq_enable() from reentrance

[Jiang Liu]

Function acpi_pci_irq_enable() may be called twice for each PCI device
present at boot time as below:
1) pci_acpi_init()
	--> acpi_pci_irq_enable()
2) pci_enable_device()
	--> pcibios_enable_device()
		--> acpi_pci_irq_enable()

So protect acpi_pci_irq_enable() from reentrance to correctly manage
IOAPIC pin reference count.

Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
---
 drivers/acpi/pci_irq.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
index 6ba463ceccc6..9d2ebd5fd9aa 100644
--- a/drivers/acpi/pci_irq.c
+++ b/drivers/acpi/pci_irq.c
@@ -413,6 +413,9 @@ int acpi_pci_irq_enable(struct pci_dev *dev)
 		return 0;
 	}
 
+	if (dev->irq > 0)
+		return 0;
+
 	entry = acpi_pci_irq_lookup(dev, pin);
 	if (!entry) {
 		/*
@@ -498,6 +501,8 @@ void acpi_pci_irq_disable(struct pci_dev *dev)
 	 */
 
 	dev_dbg(&dev->dev, "PCI INT %c disabled\n", pin_name(pin));
-	if (gsi >= 0 && dev->irq > 0)
+	if (gsi >= 0 && dev->irq > 0) {
 		acpi_unregister_gsi(gsi);
+		dev->irq = 0;
+	}
 }
-- 
1.7.10.4

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