Index: head/sys/x86/iommu/intel_fault.c
===================================================================
--- head/sys/x86/iommu/intel_fault.c
+++ head/sys/x86/iommu/intel_fault.c
@@ -291,12 +291,12 @@
 dmar_fini_fault_log(struct dmar_unit *unit)
 {
 
+	if (unit->fault_taskqueue == NULL)
+		return;
+
 	DMAR_LOCK(unit);
 	dmar_disable_fault_intr(unit);
 	DMAR_UNLOCK(unit);
-
-	if (unit->fault_taskqueue == NULL)
-		return;
 
 	taskqueue_drain(unit->fault_taskqueue, &unit->fault_task);
 	taskqueue_free(unit->fault_taskqueue);
Index: head/sys/x86/iommu/intel_gas.c
===================================================================
--- head/sys/x86/iommu/intel_gas.c
+++ head/sys/x86/iommu/intel_gas.c
@@ -546,7 +546,7 @@
 			return (EBUSY);
 		entry->start = prev->end;
 	}
-	if (next != NULL && next->start < entry->end &&
+	if (next->start < entry->end &&
 	    (next->flags & DMAR_MAP_ENTRY_PLACE) == 0) {
 		if ((next->flags & DMAR_MAP_ENTRY_RMRR) == 0)
 			return (EBUSY);
@@ -560,7 +560,7 @@
 		dmar_gas_rb_remove(domain, prev);
 		prev = NULL;
 	}
-	if (next != NULL && next->start < entry->end) {
+	if (next->start < entry->end) {
 		dmar_gas_rb_remove(domain, next);
 		next = NULL;
 	}
Index: head/sys/x86/iommu/intel_qi.c
===================================================================
--- head/sys/x86/iommu/intel_qi.c
+++ head/sys/x86/iommu/intel_qi.c
@@ -425,7 +425,7 @@
 {
 	struct dmar_qi_genseq gseq;
 
-	if (unit->qi_enabled)
+	if (!unit->qi_enabled)
 		return;
 	taskqueue_drain(unit->qi_taskqueue, &unit->qi_task);
 	taskqueue_free(unit->qi_taskqueue);