1 files changed, 20 insertions, 0 deletions

diff --git a/arch/x86_64/kernel/apic.c b/arch/x86_64/kernel/apic.c
index c02218b3ae2b..6147770b4347 100644
--- a/arch/x86_64/kernel/apic.c
+++ b/arch/x86_64/kernel/apic.c
@@ -72,6 +72,26 @@ int get_maxlvt(void)
         return maxlvt;
 }
 
+/*
+ * 'what should we do if we get a hw irq event on an illegal vector'.
+ * each architecture has to answer this themselves.
+ */
+void ack_bad_irq(unsigned int irq)
+{
+        printk("unexpected IRQ trap at vector %02x\n", irq);
+        /*
+         * Currently unexpected vectors happen only on SMP and APIC.
+         * We _must_ ack these because every local APIC has only N
+         * irq slots per priority level, and a 'hanging, unacked' IRQ
+         * holds up an irq slot - in excessive cases (when multiple
+         * unexpected vectors occur) that might lock up the APIC
+         * completely.
+         * But don't ack when the APIC is disabled. -AK
+         */
+        if (!disable_apic)
+                ack_APIC_irq();
+}
+
 void clear_local_APIC(void)
 {
         int maxlvt;