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: Jiang 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: Thomas Gleixner <tglx@linutronix.de>

diff --git a/arch/x86/pci/intel_mid_pci.c b/arch/x86/pci/intel_mid_pci.c
index b9958c3..44b9271 100644 (file)
--- a/arch/x86/pci/intel_mid_pci.c
+++ b/arch/x86/pci/intel_mid_pci.c
@@ -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 = {

diff --cc arch/x86/pci/irq.c
Simple merge

diff --cc drivers/acpi/pci_irq.c
Simple merge

diff --cc include/linux/pci.h
Simple merge