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Revert "x86/PCI: Refine the way to release PCI IRQ resources"

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Commit b4b55cda58 (Refine the way to release PCI IRQ resources)
introduced a regression in the PCI IRQ resource management by causing
the IRQ resource of a device, established when pci_enabled_device()
is called on a fully disabled device, to be released when the driver
is unbound from the device, regardless of the enable_cnt.

This leads to the situation that an ill-behaved driver can now make a
device unusable to subsequent drivers by an imbalance in their use of
pci_enable/disable_device().  That is a serious problem for secondary
drivers like vfio-pci, which are innocent of the transgressions of
the previous driver.

Since the solution of this problem is not immediate and requires
further discussion, revert commit b4b55cda58 and the issue it was
supposed to address (a bug related to xen-pciback) will be taken
care of in a different way going forward.

Reported-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Rafael J. Wysocki
2015-03-20 14:56:19 +01:00
parent 06e5801b8c
commit 9e8ce4b96b
5 changed files with 32 additions and 32 deletions
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15
arch/x86/pci/irq.c
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@@ -1256,9 +1256,22 @@ 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 && dev->irq_managed && dev->irq) {
if (io_apic_assign_pci_irqs && !mp_should_keep_irq(&dev->dev) &&
dev->irq_managed && dev->irq) {
mp_unmap_irq(dev->irq);
dev->irq = 0;
dev->irq_managed = 0;