1 files changed, 52 insertions, 0 deletions

diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h
new file mode 100644
index 000000000000..151a803ed0ed
--- /dev/null
+++ b/include/linux/stop_machine.h
@@ -0,0 +1,52 @@
+#ifndef _LINUX_STOP_MACHINE
+#define _LINUX_STOP_MACHINE
+/* "Bogolock": stop the entire machine, disable interrupts.  This is a
+   very heavy lock, which is equivalent to grabbing every spinlock
+   (and more).  So the "read" side to such a lock is anything which
+   diables preeempt. */
+#include <linux/config.h>
+#include <linux/cpu.h>
+#include <asm/system.h>
+
+#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
+/**
+ * stop_machine_run: freeze the machine on all CPUs and run this function
+ * @fn: the function to run
+ * @data: the data ptr for the @fn()
+ * @cpu: the cpu to run @fn() on (or any, if @cpu == NR_CPUS.
+ *
+ * Description: This causes a thread to be scheduled on every other cpu,
+ * each of which disables interrupts, and finally interrupts are disabled
+ * on the current CPU.  The result is that noone is holding a spinlock
+ * or inside any other preempt-disabled region when @fn() runs.
+ *
+ * This can be thought of as a very heavy write lock, equivalent to
+ * grabbing every spinlock in the kernel. */
+int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu);
+
+/**
+ * __stop_machine_run: freeze the machine on all CPUs and run this function
+ * @fn: the function to run
+ * @data: the data ptr for the @fn
+ * @cpu: the cpu to run @fn on (or any, if @cpu == NR_CPUS.
+ *
+ * Description: This is a special version of the above, which returns the
+ * thread which has run @fn(): kthread_stop will return the return value
+ * of @fn().  Used by hotplug cpu.
+ */
+struct task_struct *__stop_machine_run(int (*fn)(void *), void *data,
+                                       unsigned int cpu);
+
+#else
+
+static inline int stop_machine_run(int (*fn)(void *), void *data,
+                                   unsigned int cpu)
+{
+        int ret;
+        local_irq_disable();
+        ret = fn(data);
+        local_irq_enable();
+        return ret;
+}
+#endif /* CONFIG_SMP */
+#endif /* _LINUX_STOP_MACHINE */