1 files changed, 44 insertions, 3 deletions

diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h
index 848025cd7087..b359c4a9ec9e 100644
--- a/include/linux/nodemask.h
+++ b/include/linux/nodemask.h
@@ -82,6 +82,12 @@
  *    to generate slightly worse code.  So use a simple one-line #define
  *    for node_isset(), instead of wrapping an inline inside a macro, the
  *    way we do the other calls.
+ *
+ * NODEMASK_SCRATCH
+ * When doing above logical AND, OR, XOR, Remap operations the callers tend to
+ * need temporary nodemask_t's on the stack. But if NODES_SHIFT is large,
+ * nodemask_t's consume too much stack space.  NODEMASK_SCRATCH is a helper
+ * for such situations. See below and CPUMASK_ALLOC also.
  */
 
 #include <linux/kernel.h>
@@ -408,6 +414,19 @@ static inline int num_node_state(enum node_states state)
 #define next_online_node(nid)   next_node((nid), node_states[N_ONLINE])
 
 extern int nr_node_ids;
+extern int nr_online_nodes;
+
+static inline void node_set_online(int nid)
+{
+        node_set_state(nid, N_ONLINE);
+        nr_online_nodes = num_node_state(N_ONLINE);
+}
+
+static inline void node_set_offline(int nid)
+{
+        node_clear_state(nid, N_ONLINE);
+        nr_online_nodes = num_node_state(N_ONLINE);
+}
 #else
 
 static inline int node_state(int node, enum node_states state)
@@ -434,7 +453,10 @@ static inline int num_node_state(enum node_states state)
 #define first_online_node       0
 #define next_online_node(nid)   (MAX_NUMNODES)
 #define nr_node_ids             1
+#define nr_online_nodes         1
 
+#define node_set_online(node)      node_set_state((node), N_ONLINE)
+#define node_set_offline(node)     node_clear_state((node), N_ONLINE)
 #endif
 
 #define node_online_map         node_states[N_ONLINE]
@@ -454,10 +476,29 @@ static inline int num_node_state(enum node_states state)
 #define node_online(node)       node_state((node), N_ONLINE)
 #define node_possible(node)     node_state((node), N_POSSIBLE)
 
-#define node_set_online(node)      node_set_state((node), N_ONLINE)
-#define node_set_offline(node)     node_clear_state((node), N_ONLINE)
-
 #define for_each_node(node)        for_each_node_state(node, N_POSSIBLE)
 #define for_each_online_node(node) for_each_node_state(node, N_ONLINE)
 
+/*
+ * For nodemask scrach area.(See CPUMASK_ALLOC() in cpumask.h)
+ */
+
+#if NODES_SHIFT > 8 /* nodemask_t > 64 bytes */
+#define NODEMASK_ALLOC(x, m) struct x *m = kmalloc(sizeof(*m), GFP_KERNEL)
+#define NODEMASK_FREE(m) kfree(m)
+#else
+#define NODEMASK_ALLOC(x, m) struct x _m, *m = &_m
+#define NODEMASK_FREE(m)
+#endif
+
+/* A example struture for using NODEMASK_ALLOC, used in mempolicy. */
+struct nodemask_scratch {
+        nodemask_t      mask1;
+        nodemask_t      mask2;
+};
+
+#define NODEMASK_SCRATCH(x) NODEMASK_ALLOC(nodemask_scratch, x)
+#define NODEMASK_SCRATCH_FREE(x)  NODEMASK_FREE(x)
+
+
 #endif /* __LINUX_NODEMASK_H */