Commit cffe0a2b authored by Jiang Liu's avatar Jiang Liu Committed by Thomas Gleixner
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x86, irq: Keep balance of IOAPIC pin reference count 



To keep balance of IOAPIC pin reference count, we need to protect
pirq_enable_irq(), acpi_pci_irq_enable() and intel_mid_pci_irq_enable()
from reentrance. There are two cases which will cause reentrance.

The first case is caused by suspend/hibernation. If pcibios_disable_irq
is called during suspending/hibernating, we don't release the assigned
IRQ number, otherwise it may break the suspend/hibernation. So late when
pcibios_enable_irq is called during resume, we shouldn't allocate IRQ
number again.

The second case is that function acpi_pci_irq_enable() may be called
twice for PCI devices present at boot time as below:
1) pci_acpi_init()
	--> acpi_pci_irq_enable() if pci_routeirq is true
2) pci_enable_device()
	--> pcibios_enable_device()
		--> acpi_pci_irq_enable()
We can't kill kernel parameter pci_routeirq yet because it's still
needed for debugging purpose.

So flag irq_managed is introduced to track whether IRQ number is
assigned by OS and to protect pirq_enable_irq(), acpi_pci_irq_enable()
and intel_mid_pci_irq_enable() from reentrance.

Signed-off-by: default avatarJiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Len Brown <lenb@kernel.org>
Link: http://lkml.kernel.org/r/1414387308-27148-13-git-send-email-jiang.liu@linux.intel.com


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 67dc5e70

arch/x86/pci/intel_mid_pci.c

+9 −1
Original line number Diff line number Diff line
@@ -210,6 +210,9 @@ static int intel_mid_pci_irq_enable(struct pci_dev *dev) 
{

	int polarity;



	if (dev->irq_managed && dev->irq > 0)

		return 0;



	if (intel_mid_identify_cpu() == INTEL_MID_CPU_CHIP_TANGIER)

		polarity = 0; /* active high */

	else
@@ -224,13 +227,18 @@ static int intel_mid_pci_irq_enable(struct pci_dev *dev) 
	if (mp_map_gsi_to_irq(dev->irq, IOAPIC_MAP_ALLOC) < 0)

		return -EBUSY;



	dev->irq_managed = 1;



	return 0;

}



static void intel_mid_pci_irq_disable(struct pci_dev *dev)

{

	if (!mp_should_keep_irq(&dev->dev) && dev->irq > 0)

	if (!mp_should_keep_irq(&dev->dev) && dev->irq_managed &&

	    dev->irq > 0) {

		mp_unmap_irq(dev->irq);

		dev->irq_managed = 0;

	}

}



struct pci_ops intel_mid_pci_ops = {

arch/x86/pci/irq.c

+6 −1
Original line number Diff line number Diff line
@@ -1202,6 +1202,9 @@ static int pirq_enable_irq(struct pci_dev *dev) 
			int irq;

			struct io_apic_irq_attr irq_attr;



			if (dev->irq_managed && dev->irq > 0)

				return 0;



			irq = IO_APIC_get_PCI_irq_vector(dev->bus->number,

						PCI_SLOT(dev->devfn),

						pin - 1, &irq_attr);
@@ -1228,6 +1231,7 @@ static int pirq_enable_irq(struct pci_dev *dev) 
			}

			dev = temp_dev;

			if (irq >= 0) {

				dev->irq_managed = 1;

				dev->irq = irq;

				dev_info(&dev->dev, "PCI->APIC IRQ transform: "

					 "INT %c -> IRQ %d\n", 'A' + pin - 1, irq);
@@ -1269,8 +1273,9 @@ bool mp_should_keep_irq(struct device *dev) 
static void pirq_disable_irq(struct pci_dev *dev)

{

	if (io_apic_assign_pci_irqs && !mp_should_keep_irq(&dev->dev) &&

	    dev->irq) {

	    dev->irq_managed && dev->irq) {

		mp_unmap_irq(dev->irq);

		dev->irq = 0;

		dev->irq_managed = 0;

	}

}

drivers/acpi/pci_irq.c

+9 −2
Original line number Diff line number Diff line
@@ -413,6 +413,9 @@ int acpi_pci_irq_enable(struct pci_dev *dev) 
		return 0;

	}



	if (dev->irq_managed && dev->irq > 0)

		return 0;



	entry = acpi_pci_irq_lookup(dev, pin);

	if (!entry) {

		/*
@@ -456,6 +459,7 @@ int acpi_pci_irq_enable(struct pci_dev *dev) 
		return rc;

	}

	dev->irq = rc;

	dev->irq_managed = 1;



	if (link)

		snprintf(link_desc, sizeof(link_desc), " -> Link[%s]", link);
@@ -478,7 +482,7 @@ void acpi_pci_irq_disable(struct pci_dev *dev) 
	u8 pin;



	pin = dev->pin;

	if (!pin)

	if (!pin || !dev->irq_managed || dev->irq <= 0)

		return;



	/* Keep IOAPIC pin configuration when suspending */
@@ -506,6 +510,9 @@ 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) {

		acpi_unregister_gsi(gsi);

		dev->irq = 0;

		dev->irq_managed = 0;

	}

}

include/linux/pci.h

+1 −0
Original line number Diff line number Diff line
@@ -349,6 +349,7 @@ struct pci_dev { 
	unsigned int	__aer_firmware_first:1;

	unsigned int	broken_intx_masking:1;

	unsigned int	io_window_1k:1;	/* Intel P2P bridge 1K I/O windows */

	unsigned int	irq_managed:1;

	pci_dev_flags_t dev_flags;

	atomic_t	enable_cnt;	/* pci_enable_device has been called */

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