1 files changed, 95 insertions, 27 deletions

diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h
index baba3a23a814..6b524a0d02e4 100644
--- a/include/linux/stop_machine.h
+++ b/include/linux/stop_machine.h
@@ -1,13 +1,101 @@
 #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
-   disables preeempt. */
+
 #include <linux/cpu.h>
 #include <linux/cpumask.h>
+#include <linux/list.h>
 #include <asm/system.h>
 
+/*
+ * stop_cpu[s]() is simplistic per-cpu maximum priority cpu
+ * monopolization mechanism.  The caller can specify a non-sleeping
+ * function to be executed on a single or multiple cpus preempting all
+ * other processes and monopolizing those cpus until it finishes.
+ *
+ * Resources for this mechanism are preallocated when a cpu is brought
+ * up and requests are guaranteed to be served as long as the target
+ * cpus are online.
+ */
+typedef int (*cpu_stop_fn_t)(void *arg);
+
+#ifdef CONFIG_SMP
+
+struct cpu_stop_work {
+        struct list_head        list;           /* cpu_stopper->works */
+        cpu_stop_fn_t           fn;
+        void                    *arg;
+        struct cpu_stop_done    *done;
+};
+
+int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg);
+void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg,
+                         struct cpu_stop_work *work_buf);
+int stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
+int try_stop_cpus(const struct cpumask *cpumask, cpu_stop_fn_t fn, void *arg);
+
+#else   /* CONFIG_SMP */
+
+#include <linux/workqueue.h>
+
+struct cpu_stop_work {
+        struct work_struct      work;
+        cpu_stop_fn_t           fn;
+        void                    *arg;
+};
+
+static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
+{
+        int ret = -ENOENT;
+        preempt_disable();
+        if (cpu == smp_processor_id())
+                ret = fn(arg);
+        preempt_enable();
+        return ret;
+}
+
+static void stop_one_cpu_nowait_workfn(struct work_struct *work)
+{
+        struct cpu_stop_work *stwork =
+                container_of(work, struct cpu_stop_work, work);
+        preempt_disable();
+        stwork->fn(stwork->arg);
+        preempt_enable();
+}
+
+static inline void stop_one_cpu_nowait(unsigned int cpu,
+                                       cpu_stop_fn_t fn, void *arg,
+                                       struct cpu_stop_work *work_buf)
+{
+        if (cpu == smp_processor_id()) {
+                INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
+                work_buf->fn = fn;
+                work_buf->arg = arg;
+                schedule_work(&work_buf->work);
+        }
+}
+
+static inline int stop_cpus(const struct cpumask *cpumask,
+                            cpu_stop_fn_t fn, void *arg)
+{
+        if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
+                return stop_one_cpu(raw_smp_processor_id(), fn, arg);
+        return -ENOENT;
+}
+
+static inline int try_stop_cpus(const struct cpumask *cpumask,
+                                cpu_stop_fn_t fn, void *arg)
+{
+        return stop_cpus(cpumask, fn, arg);
+}
+
+#endif  /* CONFIG_SMP */
+
+/*
+ * 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 disables preeempt.
+ */
 #if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
 
 /**
@@ -36,24 +124,7 @@ int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
  */
 int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus);
 
-/**
- * stop_machine_create: create all stop_machine threads
- *
- * Description: This causes all stop_machine threads to be created before
- * stop_machine actually gets called. This can be used by subsystems that
- * need a non failing stop_machine infrastructure.
- */
-int stop_machine_create(void);
-
-/**
- * stop_machine_destroy: destroy all stop_machine threads
- *
- * Description: This causes all stop_machine threads which were created with
- * stop_machine_create to be destroyed again.
- */
-void stop_machine_destroy(void);
-
-#else
+#else    /* CONFIG_STOP_MACHINE && CONFIG_SMP */
 
 static inline int stop_machine(int (*fn)(void *), void *data,
                                const struct cpumask *cpus)
@@ -65,8 +136,5 @@ static inline int stop_machine(int (*fn)(void *), void *data,
         return ret;
 }
 
-static inline int stop_machine_create(void) { return 0; }
-static inline void stop_machine_destroy(void) { }
-
-#endif /* CONFIG_SMP */
-#endif /* _LINUX_STOP_MACHINE */
+#endif  /* CONFIG_STOP_MACHINE && CONFIG_SMP */
+#endif  /* _LINUX_STOP_MACHINE */