1 files changed, 8 insertions, 4 deletions

diff --git a/include/linux/idr.h b/include/linux/idr.h
index e968db71e33a..13a801f3d028 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -50,14 +50,14 @@
 
 struct idr_layer {
         unsigned long            bitmap; /* A zero bit means "space here" */
-        struct idr_layer        *ary[1<<IDR_BITS];
+        struct idr_layer __rcu  *ary[1<<IDR_BITS];
         int                      count;  /* When zero, we can release it */
         int                      layer;  /* distance from leaf */
         struct rcu_head          rcu_head;
 };
 
 struct idr {
-        struct idr_layer *top;
+        struct idr_layer __rcu *top;
         struct idr_layer *id_free;
         int               layers; /* only valid without concurrent changes */
         int               id_free_cnt;
@@ -81,6 +81,7 @@ struct idr {
 #define _idr_rc_to_errno(rc) ((rc) == -1 ? -EAGAIN : -ENOSPC)
 
 /**
+ * DOC: idr sync
  * idr synchronization (stolen from radix-tree.h)
  *
  * idr_find() is able to be called locklessly, using RCU. The caller must
@@ -117,10 +118,13 @@ void idr_init(struct idr *idp);
 /*
  * IDA - IDR based id allocator, use when translation from id to
  * pointer isn't necessary.
+ *
+ * IDA_BITMAP_LONGS is calculated to be one less to accommodate
+ * ida_bitmap->nr_busy so that the whole struct fits in 128 bytes.
  */
 #define IDA_CHUNK_SIZE          128     /* 128 bytes per chunk */
-#define IDA_BITMAP_LONGS        (128 / sizeof(long) - 1)
-#define IDA_BITMAP_BITS         (IDA_BITMAP_LONGS * sizeof(long) * 8)
+#define IDA_BITMAP_LONGS        (IDA_CHUNK_SIZE / sizeof(long) - 1)
+#define IDA_BITMAP_BITS         (IDA_BITMAP_LONGS * sizeof(long) * 8)
 
 struct ida_bitmap {
         long                    nr_busy;