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

The cpu_active() tests are not fundamentally part of stop_two_cpus(),
move then into the scheduler where they belong.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

2 files changed, 4 insertions, 9 deletions

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 7ee8caea1195..a7b368e51f69 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1335,12 +1335,16 @@ static int migrate_swap_stop(void *data)
         struct rq *src_rq, *dst_rq;
         int ret = -EAGAIN;
 
+        if (!cpu_active(arg->src_cpu) || !cpu_active(arg->dst_cpu))
+                return -EAGAIN;
+
         src_rq = cpu_rq(arg->src_cpu);
         dst_rq = cpu_rq(arg->dst_cpu);
 
         double_raw_lock(&arg->src_task->pi_lock,
                         &arg->dst_task->pi_lock);
         double_rq_lock(src_rq, dst_rq);
+
         if (task_cpu(arg->dst_task) != arg->dst_cpu)
                 goto unlock;
 
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index e5a09d2dc575..867bc20e1ef1 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -275,15 +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);
 
-        /*
-         * We do not want to migrate to inactive CPU. FIXME: move this
-         * into migrate_swap_stop() callback.
-         */
-        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)) {