srcu: Move rcu_init_levelspread() to rcu_tree_node.h

This commit moves the rcu_init_levelspread() function from
kernel/rcu/tree.c to kernel/rcu/rcu.h so that SRCU can access it.  This is
another step towards enabling SRCU to create its own combining tree.
This commit is code-movement only, give or take knock-on adjustments.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

4 files changed, 38 insertions, 25 deletions

diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h
index a943b42a9cf7..87326479b39a 100644
--- a/kernel/rcu/rcu.h
+++ b/kernel/rcu/rcu.h
@@ -190,4 +190,40 @@ void rcu_test_sync_prims(void);
  */
 extern void resched_cpu(int cpu);
 
+#if defined(SRCU) || !defined(TINY_RCU)
+
+#include <linux/rcu_node_tree.h>
+
+extern int rcu_num_lvls;
+extern int rcu_num_nodes;
+static bool rcu_fanout_exact;
+static int rcu_fanout_leaf;
+
+/*
+ * Compute the per-level fanout, either using the exact fanout specified
+ * or balancing the tree, depending on the rcu_fanout_exact boot parameter.
+ */
+static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt)
+{
+        int i;
+
+        if (rcu_fanout_exact) {
+                levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf;
+                for (i = rcu_num_lvls - 2; i >= 0; i--)
+                        levelspread[i] = RCU_FANOUT;
+        } else {
+                int ccur;
+                int cprv;
+
+                cprv = nr_cpu_ids;
+                for (i = rcu_num_lvls - 1; i >= 0; i--) {
+                        ccur = levelcnt[i];
+                        levelspread[i] = (cprv + ccur - 1) / ccur;
+                        cprv = ccur;
+                }
+        }
+}
+
+#endif /* #if defined(SRCU) || !defined(TINY_RCU) */
+
 #endif /* __LINUX_RCU_H */
diff --git a/kernel/rcu/srcu.c b/kernel/rcu/srcu.c
index 56fd30862122..0b511de7ca4d 100644
--- a/kernel/rcu/srcu.c
+++ b/kernel/rcu/srcu.c
@@ -36,6 +36,7 @@
 #include <linux/delay.h>
 #include <linux/srcu.h>
 
+#include <linux/rcu_node_tree.h>
 #include "rcu.h"
 
 static int init_srcu_struct_fields(struct srcu_struct *sp)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 844a030c1960..df3527744af8 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3952,31 +3952,6 @@ void rcu_scheduler_starting(void)
 }
 
 /*
- * Compute the per-level fanout, either using the exact fanout specified
- * or balancing the tree, depending on the rcu_fanout_exact boot parameter.
- */
-static void __init rcu_init_levelspread(int *levelspread, const int *levelcnt)
-{
-        int i;
-
-        if (rcu_fanout_exact) {
-                levelspread[rcu_num_lvls - 1] = rcu_fanout_leaf;
-                for (i = rcu_num_lvls - 2; i >= 0; i--)
-                        levelspread[i] = RCU_FANOUT;
-        } else {
-                int ccur;
-                int cprv;
-
-                cprv = nr_cpu_ids;
-                for (i = rcu_num_lvls - 1; i >= 0; i--) {
-                        ccur = levelcnt[i];
-                        levelspread[i] = (cprv + ccur - 1) / ccur;
-                        cprv = ccur;
-                }
-        }
-}
-
-/*
  * Helper function for rcu_init() that initializes one rcu_state structure.
  */
 static void __init rcu_init_one(struct rcu_state *rsp)
diff --git a/kernel/rcu/tree_trace.c b/kernel/rcu/tree_trace.c
index 066c64071a7b..30c5bf89ee58 100644
--- a/kernel/rcu/tree_trace.c
+++ b/kernel/rcu/tree_trace.c
@@ -45,6 +45,7 @@
 
 #define RCU_TREE_NONCORE
 #include "tree.h"
+#include "rcu.h"
 
 static int r_open(struct inode *inode, struct file *file,
                                         const struct seq_operations *op)