[Patch v4 21/23] x86/PCI: Refine the way to release PCI IRQ resources

Jiang Liu
2015-02-05T05:44:09Z

Some PCI device drivers assume that pci_dev->irq won't change after
calling pci_disable_device() and pci_enable_device() during suspend and
resume.

Commit c03b3b0738a5 ("x86, irq, mpparse: Release IOAPIC pin when
PCI device is disabled") frees PCI IRQ resources when pci_disable_device()
is called and reallocate IRQ resources when pci_enable_device() is
called again. This breaks above assumption. So commit 3eec595235c1
("x86, irq, PCI: Keep IRQ assignment for PCI devices during
suspend/hibernation") and 9eabc99a635a ("x86, irq, PCI: Keep IRQ
assignment for runtime power management") fix the issue by avoiding
freeing/reallocating IRQ resources during PCI device suspend/resume.
They achieve this by checking dev.power.is_prepared and
dev.power.runtime_status. PM maintainer, Rafael, then pointed out that
it's really an ugly fix which leaking PM internal state information to
IRQ subsystem.

Recently David Vrabel <david.vrabel@citrix.com> also reports an
regression in pciback driver caused by commit cffe0a2b5a34 ("x86, irq:
Keep balance of IOAPIC pin reference count"). Please refer to:
http://lkml.org/lkml/2015/1/14/546

So this patch refine the way to release PCI IRQ resources. Instead of
releasing PCI IRQ resources in pci_disable_device()/
pcibios_disable_device(), we now release it at driver unbinding
notification BUS_NOTIFY_UNBOUND_DRIVER. In other word, we only release
PCI IRQ resources when there's no driver bound to the PCI device, and
it keeps the assumption that pci_dev->irq won't through multiple
invocation of pci_enable_device()/pci_disable_device().

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
---
arch/x86/include/asm/pci_x86.h | 2 --
arch/x86/pci/common.c | 34 ++++++++++++++++++++++++++++------
arch/x86/pci/intel_mid_pci.c | 4 ++--
arch/x86/pci/irq.c | 15 +--------------
drivers/acpi/pci_irq.c | 9 +--------
5 files changed, 32 insertions(+), 32 deletions(-)

diff --git a/arch/x86/include/asm/pci_x86.h b/arch/x86/include/asm/pci_x86.h
index 164e3f8d3c3d..fa1195dae425 100644
--- a/arch/x86/include/asm/pci_x86.h
+++ b/arch/x86/include/asm/pci_x86.h
@@ -93,8 +93,6 @@ extern raw_spinlock_t pci_config_lock;
extern int (*pcibios_enable_irq)(struct pci_dev *dev);
extern void (*pcibios_disable_irq)(struct pci_dev *dev);

-extern bool mp_should_keep_irq(struct device *dev);
-
struct pci_raw_ops {
int (*read)(unsigned int domain, unsigned int bus, unsigned int devfn,
int reg, int len, u32 *val);
diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
index 7b20bccf3648..ff1f0afa5ed1 100644
--- a/arch/x86/pci/common.c
+++ b/arch/x86/pci/common.c
@@ -497,6 +497,31 @@ void __init pcibios_set_cache_line_size(void)
}
}

+/*
+ * Some device drivers assume dev->irq won't change after calling
+ * pci_disable_device(). So delay releasing of IRQ resource to driver
+ * unbinding time. Otherwise it will break PM subsystem and drivers
+ * like xen-pciback etc.
+ */
+static int pci_irq_notifier(struct notifier_block *nb, unsigned long action,
+ void *data)
+{
+ struct pci_dev *dev = to_pci_dev(data);
+
+ if (action != BUS_NOTIFY_UNBOUND_DRIVER)
+ return NOTIFY_DONE;
+
+ if (pcibios_disable_irq)
+ pcibios_disable_irq(dev);
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block pci_irq_nb = {
+ .notifier_call = pci_irq_notifier,
+ .priority = INT_MIN,
+};
+
int __init pcibios_init(void)
{
if (!raw_pci_ops) {
@@ -509,6 +534,9 @@ int __init pcibios_init(void)

if (pci_bf_sort >= pci_force_bf)
pci_sort_breadthfirst();
+
+ bus_register_notifier(&pci_bus_type, &pci_irq_nb);
+
return 0;
}

@@ -667,12 +695,6 @@ int pcibios_enable_device(struct pci_dev *dev, int mask)
return 0;
}

-void pcibios_disable_device (struct pci_dev *dev)
-{
- if (!pci_dev_msi_enabled(dev) && pcibios_disable_irq)
- pcibios_disable_irq(dev);
-}
-
int pci_ext_cfg_avail(void)
{
if (raw_pci_ext_ops)
diff --git a/arch/x86/pci/intel_mid_pci.c b/arch/x86/pci/intel_mid_pci.c
index 44b9271580b5..95c2471f6819 100644
--- a/arch/x86/pci/intel_mid_pci.c
+++ b/arch/x86/pci/intel_mid_pci.c
@@ -234,10 +234,10 @@ static int intel_mid_pci_irq_enable(struct pci_dev *dev)

static void intel_mid_pci_irq_disable(struct pci_dev *dev)
{
- if (!mp_should_keep_irq(&dev->dev) && dev->irq_managed &&
- dev->irq > 0) {
+ if (dev->irq_managed && dev->irq > 0) {
mp_unmap_irq(dev->irq);
dev->irq_managed = 0;
+ dev->irq = 0;
}
}

diff --git a/arch/x86/pci/irq.c b/arch/x86/pci/irq.c
index 5dc6ca5e1741..e71b3dbd87b8 100644
--- a/arch/x86/pci/irq.c
+++ b/arch/x86/pci/irq.c
@@ -1256,22 +1256,9 @@ static int pirq_enable_irq(struct pci_dev *dev)
return 0;
}

-bool mp_should_keep_irq(struct device *dev)
-{
- if (dev->power.is_prepared)
- return true;
-#ifdef CONFIG_PM
- if (dev->power.runtime_status == RPM_SUSPENDING)
- return true;
-#endif
-
- return false;
-}
-
static void pirq_disable_irq(struct pci_dev *dev)
{
- if (io_apic_assign_pci_irqs && !mp_should_keep_irq(&dev->dev) &&
- dev->irq_managed && dev->irq) {
+ if (io_apic_assign_pci_irqs && 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 b1def411c0b8..e7f718d6918a 100644
--- a/drivers/acpi/pci_irq.c
+++ b/drivers/acpi/pci_irq.c
@@ -485,14 +485,6 @@ void acpi_pci_irq_disable(struct pci_dev *dev)
if (!pin || !dev->irq_managed || dev->irq <= 0)
return;

- /* Keep IOAPIC pin configuration when suspending */
- if (dev->dev.power.is_prepared)
- return;
-#ifdef CONFIG_PM
- if (dev->dev.power.runtime_status == RPM_SUSPENDING)
- return;
-#endif
-
entry = acpi_pci_irq_lookup(dev, pin);
if (!entry)
return;
@@ -513,5 +505,6 @@ void acpi_pci_irq_disable(struct pci_dev *dev)
if (gsi >= 0) {
acpi_unregister_gsi(gsi);
dev->irq_managed = 0;
+ dev->irq = 0;
}
}
--
1.7.10.4