stop_machine: Kill cpu_stop_done->executed

Now that cpu_stop_done->executed becomes write-only (ignoring WARN_ON()
checks) we can remove it.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Milos Vyletel <milos@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20151115193326.GA8269@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/stop_machine.c

@@ -28,7 +28,6 @@
  */
 struct cpu_stop_done {
 	atomic_t		nr_todo;	/* nr left to execute */
-	bool			executed;	/* actually executed? */
 	int			ret;		/* collected return value */
 	struct completion	completion;	/* fired if nr_todo reaches 0 */
 };
@@ -63,11 +62,9 @@ static void cpu_stop_init_done(struct cpu_stop_done *done, unsigned int nr_todo)
 }
 
 /* signal completion unless @done is NULL */
-static void cpu_stop_signal_done(struct cpu_stop_done *done, bool executed)
+static void cpu_stop_signal_done(struct cpu_stop_done *done)
 {
 	if (done) {
-		if (executed)
-			done->executed = true;
 		if (atomic_dec_and_test(&done->nr_todo))
 			complete(&done->completion);
 	}
@@ -92,7 +89,7 @@ static bool cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work)
 	if (enabled)
 		__cpu_stop_queue_work(stopper, work);
 	else
-		cpu_stop_signal_done(work->done, false);
+		cpu_stop_signal_done(work->done);
 	spin_unlock_irqrestore(&stopper->lock, flags);
 
 	return enabled;
@@ -131,7 +128,6 @@ int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
 	if (!cpu_stop_queue_work(cpu, &work))
 		return -ENOENT;
 	wait_for_completion(&done.completion);
-	WARN_ON(!done.executed);
 	return done.ret;
 }
 
@@ -286,7 +282,6 @@ int stop_two_cpus(unsigned int cpu1, unsigned int cpu2, cpu_stop_fn_t fn, void *
 		return -ENOENT;
 
 	wait_for_completion(&done.completion);
-	WARN_ON(!done.executed);
 	return done.ret;
 }
 
@@ -354,7 +349,6 @@ static int __stop_cpus(const struct cpumask *cpumask,
 	if (!queue_stop_cpus_work(cpumask, fn, arg, &done))
 		return -ENOENT;
 	wait_for_completion(&done.completion);
-	WARN_ON(!done.executed);
 	return done.ret;
 }
 
@@ -467,6 +461,7 @@ repeat:
 		ret = fn(arg);
 		if (ret && done)
 			done->ret = ret;
+		cpu_stop_signal_done(done);
 
 		/* restore preemption and check it's still balanced */
 		preempt_enable();
@@ -475,7 +470,6 @@ repeat:
 			  kallsyms_lookup((unsigned long)fn, NULL, NULL, NULL,
 					  ksym_buf), arg);
 
-		cpu_stop_signal_done(done, true);
 		goto repeat;
 	}
 }