linux-kernel - [RFC Patch V2 07/16] x86, irq, ACPI: protect acpi_pci_irq

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Date:	Tue, 17 Jun 2014 13:29:46 +0800
From:	Jiang Liu <jiang.liu@...ux.intel.com>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Grant Likely <grant.likely@...aro.org>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Randy Dunlap <rdunlap@...radead.org>,
	Yinghai Lu <yinghai@...nel.org>, Len Brown <lenb@...nel.org>
Cc:	Jiang Liu <jiang.liu@...ux.intel.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tony Luck <tony.luck@...el.com>,
	Joerg Roedel <joro@...tes.org>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	x86@...nel.org, linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org, linux-acpi@...r.kernel.org
Subject: [RFC Patch V2 07/16] x86, irq, ACPI: protect acpi_pci_irq_enable() from reentrance

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@...ux.intel.com>
---
 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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