cpumask: split out include/linux/cpumask_types.h

Many core headers, like sched.h, include cpumask.h mostly for struct
cpumask and cpumask_var_t.  Those are frequently used headers and
shouldn't pull more than the bare minimum.

Link: https://lkml.kernel.org/r/20240528005648.182376-4-yury.norov@gmail.com
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Cc: Amit Daniel Kachhap <amit.kachhap@gmail.com>
Cc: Anna-Maria Behnsen <anna-maria@linutronix.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

MAINTAINERS

@@ -3730,6 +3730,7 @@ F:	include/linux/bitmap-str.h
 F:	include/linux/bitmap.h
 F:	include/linux/bits.h
 F:	include/linux/cpumask.h
+F:	include/linux/cpumask_types.h
 F:	include/linux/find.h
 F:	include/linux/nodemask.h
 F:	include/linux/nodemask_types.h

include/linux/cpumask.h

@@ -9,25 +9,13 @@
  */
 #include <linux/cleanup.h>
 #include <linux/kernel.h>
-#include <linux/threads.h>
 #include <linux/bitmap.h>
+#include <linux/cpumask_types.h>
 #include <linux/atomic.h>
 #include <linux/bug.h>
 #include <linux/gfp_types.h>
 #include <linux/numa.h>
 
-/* Don't assign or return these: may not be this big! */
-typedef struct cpumask { DECLARE_BITMAP(bits, NR_CPUS); } cpumask_t;
-
-/**
- * cpumask_bits - get the bits in a cpumask
- * @maskp: the struct cpumask *
- *
- * You should only assume nr_cpu_ids bits of this mask are valid.  This is
- * a macro so it's const-correct.
- */
-#define cpumask_bits(maskp) ((maskp)->bits)
-
 /**
  * cpumask_pr_args - printf args to output a cpumask
  * @maskp: cpumask to be printed
@@ -922,48 +910,7 @@ static inline unsigned int cpumask_size(void)
 	return bitmap_size(large_cpumask_bits);
 }
 
-/*
- * cpumask_var_t: struct cpumask for stack usage.
- *
- * Oh, the wicked games we play!  In order to make kernel coding a
- * little more difficult, we typedef cpumask_var_t to an array or a
- * pointer: doing &mask on an array is a noop, so it still works.
- *
- * i.e.
- *	cpumask_var_t tmpmask;
- *	if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL))
- *		return -ENOMEM;
- *
- *	  ... use 'tmpmask' like a normal struct cpumask * ...
- *
- *	free_cpumask_var(tmpmask);
- *
- *
- * However, one notable exception is there. alloc_cpumask_var() allocates
- * only nr_cpumask_bits bits (in the other hand, real cpumask_t always has
- * NR_CPUS bits). Therefore you don't have to dereference cpumask_var_t.
- *
- *	cpumask_var_t tmpmask;
- *	if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL))
- *		return -ENOMEM;
- *
- *	var = *tmpmask;
- *
- * This code makes NR_CPUS length memcopy and brings to a memory corruption.
- * cpumask_copy() provide safe copy functionality.
- *
- * Note that there is another evil here: If you define a cpumask_var_t
- * as a percpu variable then the way to obtain the address of the cpumask
- * structure differently influences what this_cpu_* operation needs to be
- * used. Please use this_cpu_cpumask_var_t in those cases. The direct use
- * of this_cpu_ptr() or this_cpu_read() will lead to failures when the
- * other type of cpumask_var_t implementation is configured.
- *
- * Please also note that __cpumask_var_read_mostly can be used to declare
- * a cpumask_var_t variable itself (not its content) as read mostly.
- */
 #ifdef CONFIG_CPUMASK_OFFSTACK
-typedef struct cpumask *cpumask_var_t;
 
 #define this_cpu_cpumask_var_ptr(x)	this_cpu_read(x)
 #define __cpumask_var_read_mostly	__read_mostly
@@ -1010,7 +957,6 @@ static inline bool cpumask_available(cpumask_var_t mask)
 }
 
 #else
-typedef struct cpumask cpumask_var_t[1];
 
 #define this_cpu_cpumask_var_ptr(x) this_cpu_ptr(x)
 #define __cpumask_var_read_mostly

include/linux/cpumask_types.h

@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LINUX_CPUMASK_TYPES_H
+#define __LINUX_CPUMASK_TYPES_H
+
+#include <linux/bitops.h>
+#include <linux/threads.h>
+
+/* Don't assign or return these: may not be this big! */
+typedef struct cpumask { DECLARE_BITMAP(bits, NR_CPUS); } cpumask_t;
+
+/**
+ * cpumask_bits - get the bits in a cpumask
+ * @maskp: the struct cpumask *
+ *
+ * You should only assume nr_cpu_ids bits of this mask are valid.  This is
+ * a macro so it's const-correct.
+ */
+#define cpumask_bits(maskp) ((maskp)->bits)
+
+/*
+ * cpumask_var_t: struct cpumask for stack usage.
+ *
+ * Oh, the wicked games we play!  In order to make kernel coding a
+ * little more difficult, we typedef cpumask_var_t to an array or a
+ * pointer: doing &mask on an array is a noop, so it still works.
+ *
+ * i.e.
+ *	cpumask_var_t tmpmask;
+ *	if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL))
+ *		return -ENOMEM;
+ *
+ *	  ... use 'tmpmask' like a normal struct cpumask * ...
+ *
+ *	free_cpumask_var(tmpmask);
+ *
+ *
+ * However, one notable exception is there. alloc_cpumask_var() allocates
+ * only nr_cpumask_bits bits (in the other hand, real cpumask_t always has
+ * NR_CPUS bits). Therefore you don't have to dereference cpumask_var_t.
+ *
+ *	cpumask_var_t tmpmask;
+ *	if (!alloc_cpumask_var(&tmpmask, GFP_KERNEL))
+ *		return -ENOMEM;
+ *
+ *	var = *tmpmask;
+ *
+ * This code makes NR_CPUS length memcopy and brings to a memory corruption.
+ * cpumask_copy() provide safe copy functionality.
+ *
+ * Note that there is another evil here: If you define a cpumask_var_t
+ * as a percpu variable then the way to obtain the address of the cpumask
+ * structure differently influences what this_cpu_* operation needs to be
+ * used. Please use this_cpu_cpumask_var_t in those cases. The direct use
+ * of this_cpu_ptr() or this_cpu_read() will lead to failures when the
+ * other type of cpumask_var_t implementation is configured.
+ *
+ * Please also note that __cpumask_var_read_mostly can be used to declare
+ * a cpumask_var_t variable itself (not its content) as read mostly.
+ */
+#ifdef CONFIG_CPUMASK_OFFSTACK
+typedef struct cpumask *cpumask_var_t;
+#else
+typedef struct cpumask cpumask_var_t[1];
+#endif /* CONFIG_CPUMASK_OFFSTACK */
+
+#endif /* __LINUX_CPUMASK_TYPES_H */