iommu/vt-d: Introduce macro for_each_dev_scope() to walk device scope entries

Introduce for_each_dev_scope()/for_each_active_dev_scope() to walk
{active} device scope entries. This will help following RCU lock
related patches.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: Joerg Roedel <joro@8bytes.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/dmar.h b/include/linux/dmar.h
index ea599d4ca9e0..4b77fd8fde76 100644
--- a/include/linux/dmar.h
+++ b/include/linux/dmar.h
@@ -65,6 +65,12 @@ extern struct list_head dmar_drhd_units;
         list_for_each_entry(drhd, &dmar_drhd_units, list)               \
                 if (i=drhd->iommu, 0) {} else 
 
+#define for_each_dev_scope(a, c, p, d)  \
+        for ((p) = 0; ((d) = (p) < (c) ? (a)[(p)] : NULL, (p) < (c)); (p)++)
+
+#define for_each_active_dev_scope(a, c, p, d)   \
+        for_each_dev_scope((a), (c), (p), (d))  if (!(d)) { continue; } else
+
 extern int dmar_table_init(void);
 extern int dmar_dev_scope_init(void);
 extern int dmar_parse_dev_scope(void *start, void *end, int *cnt,