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>

4 files changed, 25 insertions, 4 deletions

diff --git a/arch/x86/pci/intel_mid_pci.c b/arch/x86/pci/intel_mid_pci.c
index b9958c364075..44b9271580b5 100644
--- 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 --git a/arch/x86/pci/irq.c b/arch/x86/pci/irq.c
index cb50e281d838..99884588a47a 100644
--- a/arch/x86/pci/irq.c
+++ b/arch/x86/pci/irq.c
@@ -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;
         }
 }
diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
index 6e6b80eb0bba..5f1fdca65e5f 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_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;
+        }
 }
diff --git a/include/linux/pci.h b/include/linux/pci.h
index a523cee3abb5..c888c5e4e225 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -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 */