From: Jiang Liu <redacted>

This patch has been added to the 3.18 stable tree. If you have any
objections, please let us know.

===============

[ Upstream commit 8abb850a03a3a8b11a0e92949e5b99d9cc178e35 ]

Xen overrides __acpi_register_gsi and leaves __acpi_unregister_gsi as is.
That means, an IRQ allocated by acpi_register_gsi_xen_hvm() or
acpi_register_gsi_xen() will be freed by acpi_unregister_gsi_ioapic(),
which may cause undesired effects. So override __acpi_unregister_gsi to
NULL for safety.

Signed-off-by: Jiang Liu <redacted>
Tested-by: Sander Eikelenboom <redacted>
Cc: Tony Luck <tony.luck@intel.com>
Cc: xen-devel@lists.xenproject.org
Cc: Konrad Rzeszutek Wilk <redacted>
Cc: David Vrabel <redacted>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Graeme Gregory <redacted>
Cc: Lv Zheng <redacted>
Link: http://lkml.kernel.org/r/1421720467-7709-4-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <redacted>
Signed-off-by: Sasha Levin <redacted>
---
 arch/x86/include/asm/acpi.h | 1 +
 arch/x86/pci/xen.c          | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/arch/x86/include/asm/acpi.h b/arch/x86/include/asm/acpi.h
index 0ab4f9f..3a45668 100644
--- a/arch/x86/include/asm/acpi.h
+++ b/arch/x86/include/asm/acpi.h

@@ -50,6 +50,7 @@ void acpi_pic_sci_set_trigger(unsigned int, u16);
 
 extern int (*__acpi_register_gsi)(struct device *dev, u32 gsi,
 				  int trigger, int polarity);
+extern void (*__acpi_unregister_gsi)(u32 gsi);
 
 static inline void disable_acpi(void)
 {

diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
index 6b3cf7c..3c41716 100644
--- a/arch/x86/pci/xen.c
+++ b/arch/x86/pci/xen.c

@@ -442,6 +442,7 @@ int __init pci_xen_hvm_init(void)
 	 * just how GSIs get registered.
 	 */
 	__acpi_register_gsi = acpi_register_gsi_xen_hvm;
+	__acpi_unregister_gsi = NULL;
 #endif
 
 #ifdef CONFIG_PCI_MSI

@@ -464,6 +465,7 @@ int __init pci_xen_initial_domain(void)
 	x86_msi.msix_mask_irq = xen_nop_msix_mask_irq;
 #endif
 	__acpi_register_gsi = acpi_register_gsi_xen;
+	__acpi_unregister_gsi = NULL;
 	/* Pre-allocate legacy irqs */
 	for (irq = 0; irq < nr_legacy_irqs(); irq++) {
 		int trigger, polarity;

-- 
2.5.0