From: Jeff Mahoney <jeffm@suse.com>
Subject: dmar: Fix oops with no DMAR table
References: bnc#548108
Patch-mainline: submitted 17 Mar 2010

 On systems without a DMAR table and with DMAR enabled, we will oops
 in dmar_ir_supported. This patch makes sure we actually have a DMAR
 table before checking it.


Signed-off-by: Jeff Mahoney <jeffm@suse.com>
---

 drivers/pci/dmar.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/pci/dmar.c
+++ b/drivers/pci/dmar.c
@@ -1460,5 +1460,5 @@ int __init dmar_ir_support(void)
 {
 	struct acpi_table_dmar *dmar;
 	dmar = (struct acpi_table_dmar *)dmar_tbl;
-	return dmar->flags & 0x1;
+	return dmar && dmar->flags & 0x1;
 }