Merge "stop_machine: Reflow cpu_stop_queue_two_works()" (36ab69de) · Commits · e / devices / android_kernel_oneplus_sm8150

kernel/stop_machine.c

+23 −18

Original line number	Diff line number	Diff line
		@@ -238,13 +238,24 @@ static int cpu_stop_queue_two_works(int cpu1, struct cpu_stop_work *work1,
		struct cpu_stopper *stopper2 = per_cpu_ptr(&cpu_stopper, cpu2);
		DEFINE_WAKE_Q(wakeq);
		int err;

		retry:
		/*
		* The waking up of stopper threads has to happen in the same
		* scheduling context as the queueing. Otherwise, there is a
		* possibility of one of the above stoppers being woken up by another
		* CPU, and preempting us. This will cause us to not wake up the other
		* stopper forever.
		*/
		preempt_disable();
		raw_spin_lock_irq(&stopper1->lock);
		raw_spin_lock_nested(&stopper2->lock, SINGLE_DEPTH_NESTING);

		if (!stopper1->enabled \|\| !stopper2->enabled) {
		err = -ENOENT;
		if (!stopper1->enabled \|\| !stopper2->enabled)
		goto unlock;
		}

		/*
		* Ensure that if we race with __stop_cpus() the stoppers won't get
		* queued up in reverse order leading to system deadlock.
		@@ -255,36 +266,30 @@ static int cpu_stop_queue_two_works(int cpu1, struct cpu_stop_work *work1,
		* It can be falsely true but it is safe to spin until it is cleared,
		* queue_stop_cpus_work() does everything under preempt_disable().
		*/
		if (unlikely(stop_cpus_in_progress)) {
		err = -EDEADLK;
		if (unlikely(stop_cpus_in_progress))
		goto unlock;
		}

		err = 0;
		__cpu_stop_queue_work(stopper1, work1, &wakeq);
		__cpu_stop_queue_work(stopper2, work2, &wakeq);
		/*
		* The waking up of stopper threads has to happen
		* in the same scheduling context as the queueing.
		* Otherwise, there is a possibility of one of the
		* above stoppers being woken up by another CPU,
		* and preempting us. This will cause us to not
		* wake up the other stopper forever.
		*/
		preempt_disable();

		unlock:
		raw_spin_unlock(&stopper2->lock);
		raw_spin_unlock_irq(&stopper1->lock);

		if (unlikely(err == -EDEADLK)) {
		preempt_enable();

		while (stop_cpus_in_progress)
		cpu_relax();

		goto retry;
		}

		if (!err) {
		wake_up_q(&wakeq);
		preempt_enable();
		}

		return err;
		}