Merge "cpu-hotplug: Always use real time scheduling when hotplugging a CPU" into msm-4.9 (023a1495) · Commits · e / devices / android_kernel_fairphone_FP3

kernel/cpu.c

+39 −0

Original line number	Diff line number	Diff line
		@@ -1060,9 +1060,37 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
		return ret;
		}

		static int switch_to_rt_policy(void)
		{
		struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
		unsigned int policy = current->policy;
		int err;

		/* Nobody should be attempting hotplug from these policy contexts. */
		if (policy == SCHED_BATCH \|\| policy == SCHED_IDLE \|\|
		policy == SCHED_DEADLINE)
		return -EPERM;

		if (policy == SCHED_FIFO \|\| policy == SCHED_RR)
		return 1;

		/* Only SCHED_NORMAL left. */
		err = sched_setscheduler_nocheck(current, SCHED_FIFO, &param);
		return err;

		}

		static int switch_to_fair_policy(void)
		{
		struct sched_param param = { .sched_priority = 0 };

		return sched_setscheduler_nocheck(current, SCHED_NORMAL, &param);
		}

		static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
		{
		int err = 0;
		int switch_err = 0;

		if (!cpu_possible(cpu)) {
		pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n",
		@@ -1073,6 +1101,10 @@ static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
		return -EINVAL;
		}

		switch_err = switch_to_rt_policy();
		if (switch_err < 0)
		return switch_err;

		err = try_online_node(cpu_to_node(cpu));
		if (err)
		return err;
		@@ -1087,6 +1119,13 @@ static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
		err = _cpu_up(cpu, 0, target);
		out:
		cpu_maps_update_done();

		if (!switch_err) {
		switch_err = switch_to_fair_policy();
		pr_err("Hotplug policy switch err. Task %s pid=%d\n",
		current->comm, current->pid);
		}

		return err;
		}