[PATCH 1/2] nodemask: Introduce for_each_node_mask_from/for_each_node_state_from()

[Andrea Righi <arighi@nvidia.com>]

Introduce NUMA node iterators to support circular iteration, starting
from a specified node.

Signed-off-by: Andrea Righi <arighi@nvidia.com>
---
 include/linux/nodemask.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/include/linux/nodemask.h b/include/linux/nodemask.h
index b61438313a73..35f1fcdd6a84 100644
--- a/include/linux/nodemask.h
+++ b/include/linux/nodemask.h
@@ -392,6 +392,21 @@ static inline void __nodes_fold(nodemask_t *dstp, const nodemask_t *origp,
 	for ((node) = 0; (node) < 1 && !nodes_empty(mask); (node)++)
 #endif /* MAX_NUMNODES */
 
+#if MAX_NUMNODES > 1
+#define for_each_node_mask_from(node, mask, start, cnt)			\
+	for ((node) = (start), (cnt) = 0;				\
+	     (cnt) == 0 || (node) != (start);				\
+	     (cnt)++, (node) =						\
+			next_node((node), (mask)) >= MAX_NUMNODES ?	\
+				first_node(mask) :			\
+				next_node((node), (mask)))
+#else /* MAX_NUMNODES == 1 */
+#define for_each_node_mask_from(node, mask, start, cnt)			\
+	for ((node) = 0;						\
+	     (node) < 1 && !nodes_empty(mask);				\
+	     (node)++, (void)(start), (void)(cnt))
+#endif /* MAX_NUMNODES */
+
 /*
  * Bitmasks that are kept for all the nodes.
  */
@@ -441,6 +456,9 @@ static inline int num_node_state(enum node_states state)
 #define for_each_node_state(__node, __state) \
 	for_each_node_mask((__node), node_states[__state])
 
+#define for_each_node_state_from(__node, __state, __start, __cnt) \
+	for_each_node_mask_from((__node), node_states[__state], __start, __cnt)
+
 #define first_online_node	first_node(node_states[N_ONLINE])
 #define first_memory_node	first_node(node_states[N_MEMORY])
 static inline unsigned int next_online_node(int nid)
-- 
2.47.0