refcount: Split out refcount_types.h

More trimming of sched.h dependencies.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

include/linux/refcount.h

@@ -96,22 +96,11 @@
 #include <linux/bug.h>
 #include <linux/compiler.h>
 #include <linux/limits.h>
+#include <linux/refcount_types.h>
 #include <linux/spinlock_types.h>
 
 struct mutex;
 
-/**
- * typedef refcount_t - variant of atomic_t specialized for reference counts
- * @refs: atomic_t counter field
- *
- * The counter saturates at REFCOUNT_SATURATED and will not move once
- * there. This avoids wrapping the counter and causing 'spurious'
- * use-after-free bugs.
- */
-typedef struct refcount_struct {
-	atomic_t refs;
-} refcount_t;
-
 #define REFCOUNT_INIT(n)	{ .refs = ATOMIC_INIT(n), }
 #define REFCOUNT_MAX		INT_MAX
 #define REFCOUNT_SATURATED	(INT_MIN / 2)

include/linux/refcount_types.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_REFCOUNT_TYPES_H
+#define _LINUX_REFCOUNT_TYPES_H
+
+#include <linux/types.h>
+
+/**
+ * typedef refcount_t - variant of atomic_t specialized for reference counts
+ * @refs: atomic_t counter field
+ *
+ * The counter saturates at REFCOUNT_SATURATED and will not move once
+ * there. This avoids wrapping the counter and causing 'spurious'
+ * use-after-free bugs.
+ */
+typedef struct refcount_struct {
+	atomic_t refs;
+} refcount_t;
+
+#endif /* _LINUX_REFCOUNT_TYPES_H */

include/linux/sched.h

@@ -22,7 +22,7 @@
 #include <linux/seccomp.h>
 #include <linux/nodemask_types.h>
 #include <linux/rcupdate.h>
-#include <linux/refcount.h>
+#include <linux/refcount_types.h>
 #include <linux/resource.h>
 #include <linux/latencytop.h>
 #include <linux/sched/prio.h>

include/linux/sched/task.h

@@ -7,6 +7,7 @@
  * functionality:
  */
 
+#include <linux/refcount.h>
 #include <linux/sched.h>
 #include <linux/uaccess.h>