[Patch v4 09/16] x86, irq: Keep balance of IOAPIC pin reference count

Jiang Liu
2014-08-28T02:22:34Z

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>
---
arch/x86/pci/intel_mid_pci.c | 9 ++++++++-
arch/x86/pci/irq.c | 7 ++++++-
drivers/acpi/pci_irq.c | 11 +++++++++--
include/linux/pci.h | 1 +
4 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/arch/x86/pci/intel_mid_pci.c b/arch/x86/pci/intel_mid_pci.c
index 3865116c51fb..6a855fef78fc 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 +227,17 @@ 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 (!dev->dev.power.is_prepared && dev->irq > 0)
+ if (!dev->dev.power.is_prepared && 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 bc1a2c341891..dd1369dbcc42 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);
@@ -1257,8 +1261,9 @@ static int pirq_enable_irq(struct pci_dev *dev)
static void pirq_disable_irq(struct pci_dev *dev)
{
if (io_apic_assign_pci_irqs && !dev->dev.power.is_prepared &&
- dev->irq) {
+ dev->irq_managed && dev->irq > 0) {
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 c96887d5289e..4a89701dfe36 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 */
@@ -502,6 +506,9 @@ 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 61978a460841..3e0b92715512 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -347,6 +347,7 @@ 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 */

--
1.7.10.4