[PATCH v4 1/4] cpu: Move CPU hotplug function declarations into their own header

[Tony Luck]

Avoid upcoming #include hell when <linux/cachinfo.h> wants to use
lockdep_assert_cpus_held() and creates a #include loop that would
break the build for arch/riscv.

Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
---
 include/linux/cpu.h       | 33 +--------------------------
 include/linux/cpuhplock.h | 47 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 32 deletions(-)
 create mode 100644 include/linux/cpuhplock.h

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 861c3bfc5f17..a8926d0a28cd 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -18,6 +18,7 @@
 #include <linux/compiler.h>
 #include <linux/cpumask.h>
 #include <linux/cpuhotplug.h>
+#include <linux/cpuhplock.h>
 #include <linux/cpu_smt.h>
 
 struct device;
@@ -132,38 +133,6 @@ static inline int add_cpu(unsigned int cpu) { return 0;}
 #endif /* CONFIG_SMP */
 extern const struct bus_type cpu_subsys;
 
-extern int lockdep_is_cpus_held(void);
-
-#ifdef CONFIG_HOTPLUG_CPU
-extern void cpus_write_lock(void);
-extern void cpus_write_unlock(void);
-extern void cpus_read_lock(void);
-extern void cpus_read_unlock(void);
-extern int  cpus_read_trylock(void);
-extern void lockdep_assert_cpus_held(void);
-extern void cpu_hotplug_disable(void);
-extern void cpu_hotplug_enable(void);
-void clear_tasks_mm_cpumask(int cpu);
-int remove_cpu(unsigned int cpu);
-int cpu_device_down(struct device *dev);
-extern void smp_shutdown_nonboot_cpus(unsigned int primary_cpu);
-
-#else /* CONFIG_HOTPLUG_CPU */
-
-static inline void cpus_write_lock(void) { }
-static inline void cpus_write_unlock(void) { }
-static inline void cpus_read_lock(void) { }
-static inline void cpus_read_unlock(void) { }
-static inline int  cpus_read_trylock(void) { return true; }
-static inline void lockdep_assert_cpus_held(void) { }
-static inline void cpu_hotplug_disable(void) { }
-static inline void cpu_hotplug_enable(void) { }
-static inline int remove_cpu(unsigned int cpu) { return -EPERM; }
-static inline void smp_shutdown_nonboot_cpus(unsigned int primary_cpu) { }
-#endif	/* !CONFIG_HOTPLUG_CPU */
-
-DEFINE_LOCK_GUARD_0(cpus_read_lock, cpus_read_lock(), cpus_read_unlock())
-
 #ifdef CONFIG_PM_SLEEP_SMP
 extern int freeze_secondary_cpus(int primary);
 extern void thaw_secondary_cpus(void);
diff --git a/include/linux/cpuhplock.h b/include/linux/cpuhplock.h
new file mode 100644
index 000000000000..d42d2434dab6
--- /dev/null
+++ b/include/linux/cpuhplock.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * include/linux/cpuhplock.h - cpu hotplug locking
+ *
+ * Locking functions for CPU hot plug.
+ */
+#ifndef _LINUX_CPUHPLOCK_H_
+#define _LINUX_CPUHPLOCK_H_
+
+#include <linux/cleanup.h>
+#include <linux/errno.h>
+
+struct device;
+
+extern int lockdep_is_cpus_held(void);
+
+#ifdef CONFIG_HOTPLUG_CPU
+extern void cpus_write_lock(void);
+extern void cpus_write_unlock(void);
+extern void cpus_read_lock(void);
+extern void cpus_read_unlock(void);
+extern int  cpus_read_trylock(void);
+extern void lockdep_assert_cpus_held(void);
+extern void cpu_hotplug_disable(void);
+extern void cpu_hotplug_enable(void);
+void clear_tasks_mm_cpumask(int cpu);
+int remove_cpu(unsigned int cpu);
+int cpu_device_down(struct device *dev);
+extern void smp_shutdown_nonboot_cpus(unsigned int primary_cpu);
+
+#else /* CONFIG_HOTPLUG_CPU */
+
+static inline void cpus_write_lock(void) { }
+static inline void cpus_write_unlock(void) { }
+static inline void cpus_read_lock(void) { }
+static inline void cpus_read_unlock(void) { }
+static inline int  cpus_read_trylock(void) { return true; }
+static inline void lockdep_assert_cpus_held(void) { }
+static inline void cpu_hotplug_disable(void) { }
+static inline void cpu_hotplug_enable(void) { }
+static inline int remove_cpu(unsigned int cpu) { return -EPERM; }
+static inline void smp_shutdown_nonboot_cpus(unsigned int primary_cpu) { }
+#endif	/* !CONFIG_HOTPLUG_CPU */
+
+DEFINE_LOCK_GUARD_0(cpus_read_lock, cpus_read_lock(), cpus_read_unlock())
+
+#endif /* _LINUX_CPUHPLOCK_H_ */
-- 
2.45.0