1 files changed, 9 insertions, 3 deletions

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 332512767f4f..da10f07fc59c 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -326,12 +326,16 @@ static void __cpuinit start_secondary(void *unused)
          * for which cpus receive the IPI. Holding this
          * lock helps us to not include this cpu in a currently in progress
          * smp_call_function().
+         *
+         * We need to hold vector_lock so there the set of online cpus
+         * does not change while we are assigning vectors to cpus.  Holding
+         * this lock ensures we don't half assign or remove an irq from a cpu.
          */
         ipi_call_lock_irq();
-#ifdef CONFIG_X86_IO_APIC
-        setup_vector_irq(smp_processor_id());
-#endif
+        lock_vector_lock();
+        __setup_vector_irq(smp_processor_id());
         cpu_set(smp_processor_id(), cpu_online_map);
+        unlock_vector_lock();
         ipi_call_unlock_irq();
         per_cpu(cpu_state, smp_processor_id()) = CPU_ONLINE;
 
@@ -1336,7 +1340,9 @@ int __cpu_disable(void)
         remove_siblinginfo(cpu);
 
         /* It's now safe to remove this processor from the online map */
+        lock_vector_lock();
         remove_cpu_from_maps(cpu);
+        unlock_vector_lock();
         fixup_irqs(cpu_online_map);
         return 0;
 }