sched: Move cpu_active() tests from stop_two_cpus() into migrate_swap_stop()

[cascardo/linux.git] / kernel / stop_machine.c

diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 688d6b3..867bc20 100644 (file)
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -219,12 +219,27 @@ static int multi_cpu_stop(void *data)
 static int cpu_stop_queue_two_works(int cpu1, struct cpu_stop_work *work1,
                                    int cpu2, struct cpu_stop_work *work2)
 {
+       struct cpu_stopper *stopper1 = per_cpu_ptr(&cpu_stopper, cpu1);
+       struct cpu_stopper *stopper2 = per_cpu_ptr(&cpu_stopper, cpu2);
+       int err;
+
        lg_double_lock(&stop_cpus_lock, cpu1, cpu2);
-       cpu_stop_queue_work(cpu1, work1);
-       cpu_stop_queue_work(cpu2, work2);
+       spin_lock_irq(&stopper1->lock);
+       spin_lock_nested(&stopper2->lock, SINGLE_DEPTH_NESTING);
+
+       err = -ENOENT;
+       if (!stopper1->enabled || !stopper2->enabled)
+               goto unlock;
+
+       err = 0;
+       __cpu_stop_queue_work(stopper1, work1);
+       __cpu_stop_queue_work(stopper2, work2);
+unlock:
+       spin_unlock(&stopper2->lock);
+       spin_unlock_irq(&stopper1->lock);
        lg_double_unlock(&stop_cpus_lock, cpu1, cpu2);
 
-       return 0;
+       return err;
 }
 /**
  * stop_two_cpus - stops two cpus
@@ -260,19 +275,6 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *
        cpu_stop_init_done(&done, 2);
        set_state(&msdata, MULTI_STOP_PREPARE);
 
-       /*
-        * If we observe both CPUs active we know _cpu_down() cannot yet have
-        * queued its stop_machine works and therefore ours will get executed
-        * first. Or its not either one of our CPUs that's getting unplugged,
-        * in which case we don't care.
-        *
-        * This relies on the stopper workqueues to be FIFO.
-        */
-       if (!cpu_active(cpu1) || !cpu_active(cpu2)) {
-               preempt_enable();
-               return -ENOENT;
-       }
-
        if (cpu1 > cpu2)
                swap(cpu1, cpu2);
        if (cpu_stop_queue_two_works(cpu1, &work1, cpu2, &work2)) {
@@ -493,13 +495,12 @@ static void cpu_stop_park(unsigned int cpu)
        WARN_ON(!list_empty(&stopper->works));
 }
 
-static void cpu_stop_unpark(unsigned int cpu)
+void stop_machine_unpark(int cpu)
 {
        struct cpu_stopper *stopper = &per_cpu(cpu_stopper, cpu);
 
-       spin_lock_irq(&stopper->lock);
        stopper->enabled = true;
-       spin_unlock_irq(&stopper->lock);
+       kthread_unpark(stopper->thread);
 }
 
 static struct smp_hotplug_thread cpu_stop_threads = {
@@ -508,9 +509,7 @@ static struct smp_hotplug_thread cpu_stop_threads = {
        .thread_fn              = cpu_stopper_thread,
        .thread_comm            = "migration/%u",
        .create                 = cpu_stop_create,
-       .setup                  = cpu_stop_unpark,
        .park                   = cpu_stop_park,
-       .pre_unpark             = cpu_stop_unpark,
        .selfparking            = true,
 };
 
@@ -526,6 +525,7 @@ static int __init cpu_stop_init(void)
        }
 
        BUG_ON(smpboot_register_percpu_thread(&cpu_stop_threads));
+       stop_machine_unpark(raw_smp_processor_id());
        stop_machine_initialized = true;
        return 0;
 }