[PATCH v2 01/14] smp: Create a new function to shutdown nonboot cpus

[Qais Yousef <qais.yousef@xxxxxxx>]

This function will be used later in machine_shutdown() for some archs.

Signed-off-by: Qais Yousef <qais.yousef@xxxxxxx>
CC: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CC: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
CC: "Peter Zijlstra (Intel)" <peterz@xxxxxxxxxxxxx>
CC: Jiri Kosina <jkosina@xxxxxxx>
CC: Nicholas Piggin <npiggin@xxxxxxxxx>
CC: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>
CC: Ingo Molnar <mingo@xxxxxxxxxx>
CC: Eiichi Tsukata <devel@xxxxxxxxxxxx>
CC: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxxx>
CC: Nadav Amit <namit@xxxxxxxxxx>
CC: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
CC: "Rafael J. Wysocki" <rafael.j.wysocki@xxxxxxxxx>
CC: Tony Luck <tony.luck@xxxxxxxxx>
CC: Fenghua Yu <fenghua.yu@xxxxxxxxx>
CC: Russell King <linux@xxxxxxxxxxxxxxx>
CC: Catalin Marinas <catalin.marinas@xxxxxxx>
CC: Will Deacon <will@xxxxxxxxxx>
CC: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
CC: linux-ia64@xxxxxxxxxxxxxxx
CC: linux-kernel@xxxxxxxxxxxxxxx
---
 include/linux/cpu.h |  2 ++
 kernel/cpu.c        | 17 +++++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index bc6c879bd110..8229932fb053 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -118,6 +118,7 @@ extern void cpu_hotplug_disable(void);
 extern void cpu_hotplug_enable(void);
 void clear_tasks_mm_cpumask(int cpu);
 int cpu_down(unsigned int cpu);
+extern void smp_shutdown_nonboot_cpus(unsigned int primary_cpu);
 
 #else /* CONFIG_HOTPLUG_CPU */
 
@@ -129,6 +130,7 @@ 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 void smp_shutdown_nonboot_cpus(unsigned int primary_cpu) { }
 #endif	/* !CONFIG_HOTPLUG_CPU */
 
 /* Wrappers which go away once all code is converted */
diff --git a/kernel/cpu.c b/kernel/cpu.c
index e2cad3ee2ead..94055a0d989e 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1058,6 +1058,23 @@ int cpu_down(unsigned int cpu)
 }
 EXPORT_SYMBOL(cpu_down);
 
+void smp_shutdown_nonboot_cpus(unsigned int primary_cpu)
+{
+	unsigned int cpu;
+
+	if (!cpu_online(primary_cpu)) {
+		pr_info("Attempting to shutdodwn nonboot cpus while boot cpu is offline!\n");
+		cpu_online(primary_cpu);
+	}
+
+	for_each_present_cpu(cpu) {
+		if (cpu == primary_cpu)
+			continue;
+		if (cpu_online(cpu))
+			cpu_down(cpu);
+	}
+}
+
 #else
 #define takedown_cpu		NULL
 #endif /*CONFIG_HOTPLUG_CPU*/
-- 
2.17.1