diff -r cc339ab1d917 -r fd4fd4868325 xen/arch/x86/irq.c
--- a/xen/arch/x86/irq.c	Thu Sep 22 18:37:06 2011 +0100
+++ b/xen/arch/x86/irq.c	Wed Sep 28 11:16:37 2011 +0100
@@ -225,6 +225,9 @@ static void __clear_irq_vector(int irq)
     for_each_cpu_mask(cpu, tmp_mask)
         per_cpu(vector_irq, cpu)[vector] = -1;
 
+    if ( cfg->used_vectors )
+        clear_bit(vector, cfg->used_vectors);
+
     cfg->vector = IRQ_VECTOR_UNASSIGNED;
     cpus_clear(cfg->cpu_mask);
     cfg->used = IRQ_UNUSED;
@@ -239,12 +242,6 @@ static void __clear_irq_vector(int irq)
         per_cpu(vector_irq, cpu)[cfg->old_vector] = -1;
      }
 
-    if ( cfg->used_vectors )
-    {
-        ASSERT(test_bit(vector, cfg->used_vectors));
-        clear_bit(vector, cfg->used_vectors);
-    }
-
     cfg->move_in_progress = 0;
     cfg->old_vector = IRQ_VECTOR_UNASSIGNED;
     cpus_clear(cfg->old_cpu_mask);