3 files changed, 43 insertions, 5 deletions

diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
index c8e169e46673..2c45dd3acc17 100644
--- a/drivers/acpi/pci_irq.c
+++ b/drivers/acpi/pci_irq.c
@@ -33,6 +33,7 @@
 #include <linux/pci.h>
 #include <linux/acpi.h>
 #include <linux/slab.h>
+#include <linux/interrupt.h>
 
 #define PREFIX "ACPI: "
 
@@ -387,6 +388,23 @@ static inline int acpi_isa_register_gsi(struct pci_dev *dev)
 }
 #endif
 
+static inline bool acpi_pci_irq_valid(struct pci_dev *dev, u8 pin)
+{
+#ifdef CONFIG_X86
+        /*
+         * On x86 irq line 0xff means "unknown" or "no connection"
+         * (PCI 3.0, Section 6.2.4, footnote on page 223).
+         */
+        if (dev->irq == 0xff) {
+                dev->irq = IRQ_NOTCONNECTED;
+                dev_warn(&dev->dev, "PCI INT %c: not connected\n",
+                         pin_name(pin));
+                return false;
+        }
+#endif
+        return true;
+}
+
 int acpi_pci_irq_enable(struct pci_dev *dev)
 {
         struct acpi_prt_entry *entry;
@@ -431,11 +449,14 @@ int acpi_pci_irq_enable(struct pci_dev *dev)
         } else
                 gsi = -1;
 
-        /*
-         * No IRQ known to the ACPI subsystem - maybe the BIOS / 
-         * driver reported one, then use it. Exit in any case.
-         */
         if (gsi < 0) {
+                /*
+                 * No IRQ known to the ACPI subsystem - maybe the BIOS /
+                 * driver reported one, then use it. Exit in any case.
+                 */
+                if (!acpi_pci_irq_valid(dev, pin))
+                        return 0;
+
                 if (acpi_isa_register_gsi(dev))
                         dev_warn(&dev->dev, "PCI INT %c: no GSI\n",
                                  pin_name(pin));
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 0e95fcc75b2a..358076eda364 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -125,6 +125,16 @@ struct irqaction {
 
 extern irqreturn_t no_action(int cpl, void *dev_id);
 
+/*
+ * If a (PCI) device interrupt is not connected we set dev->irq to
+ * IRQ_NOTCONNECTED. This causes request_irq() to fail with -ENOTCONN, so we
+ * can distingiush that case from other error returns.
+ *
+ * 0x80000000 is guaranteed to be outside the available range of interrupts
+ * and easy to distinguish from other possible incorrect values.
+ */
+#define IRQ_NOTCONNECTED        (1U << 31)
+
 extern int __must_check
 request_threaded_irq(unsigned int irq, irq_handler_t handler,
                      irq_handler_t thread_fn,
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 841187239adc..e79e60f50bce 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1609,6 +1609,9 @@ int request_threaded_irq(unsigned int irq, irq_handler_t handler,
         struct irq_desc *desc;
         int retval;
 
+        if (irq == IRQ_NOTCONNECTED)
+                return -ENOTCONN;
+
         /*
          * Sanity-check: shared interrupts must pass in a real dev-ID,
          * otherwise we'll have trouble later trying to figure out
@@ -1699,9 +1702,13 @@ EXPORT_SYMBOL(request_threaded_irq);
 int request_any_context_irq(unsigned int irq, irq_handler_t handler,
                             unsigned long flags, const char *name, void *dev_id)
 {
-        struct irq_desc *desc = irq_to_desc(irq);
+        struct irq_desc *desc;
         int ret;
 
+        if (irq == IRQ_NOTCONNECTED)
+                return -ENOTCONN;
+
+        desc = irq_to_desc(irq);
         if (!desc)
                 return -EINVAL;