Merge "PM / devfreq: memlat: Prevent deadlock with hotplug in start_hwmon" (249fad2f) · Commits · e / devices / android_kernel_xiaomi_markw

drivers/devfreq/arm-memlat-mon.c

+7 −39

Original line number	Diff line number	Diff line
		/*
		* Copyright (c) 2014-2015, The Linux Foundation. All rights reserved.
		* Copyright (c) 2014-2016, The Linux Foundation. All rights reserved.
		*
		* This program is free software; you can redistribute it and/or modify
		* it under the terms of the GNU General Public License version 2 and
		@@ -57,14 +57,9 @@ static DEFINE_PER_CPU(struct memlat_hwmon_data, pm_data);
		struct cpu_grp_info {
		cpumask_t cpus;
		struct memlat_hwmon hw;
		struct notifier_block arm_memlat_cpu_notif;
		};

		static DEFINE_MUTEX(notif_mutex);
		static unsigned int notif_refcount;
		static void notif_unregister_work_fn(struct work_struct *work);
		static void hotplug_notif_unregister(void);
		static DECLARE_WORK(notif_unregister_work, notif_unregister_work_fn);

		static unsigned long compute_freq(struct memlat_hwmon_data *hw_data,
		unsigned long cyc_cnt)
		{
		@@ -155,7 +150,7 @@ static void stop_hwmon(struct memlat_hwmon *hw)
		for_each_cpu(cpu, &cpu_grp->cpus) {
		hw_data = &per_cpu(pm_data, cpu);
		if (hw_data->init_pending)
		hotplug_notif_unregister();
		hw_data->init_pending = false;
		else
		delete_events(hw_data);

		@@ -167,6 +162,7 @@ static void stop_hwmon(struct memlat_hwmon *hw)
		}
		put_online_cpus();

		unregister_cpu_notifier(&cpu_grp->arm_memlat_cpu_notif);
		}

		static struct perf_event_attr *alloc_attr(void)
		@@ -239,40 +235,10 @@ static int arm_memlat_cpu_callback(struct notifier_block *nb,
		pr_warn("Failed to create perf event for CPU%lu\n", cpu);

		hw_data->init_pending = false;
		hotplug_notif_unregister();

		return NOTIFY_OK;
		}

		static struct notifier_block arm_memlat_cpu_notifier = {
		.notifier_call = arm_memlat_cpu_callback,
		};

		static void notif_unregister_work_fn(struct work_struct *work)
		{
		unregister_cpu_notifier(&arm_memlat_cpu_notifier);
		}

		static void hotplug_notif_register(void)
		{
		mutex_lock(&notif_mutex);
		if (!notif_refcount) {
		flush_work(&notif_unregister_work);
		register_cpu_notifier(&arm_memlat_cpu_notifier);
		}
		notif_refcount++;
		mutex_unlock(&notif_mutex);
		}

		static void hotplug_notif_unregister(void)
		{
		mutex_lock(&notif_mutex);
		notif_refcount--;
		if (!notif_refcount)
		schedule_work(&notif_unregister_work);
		mutex_unlock(&notif_mutex);
		}

		static int start_hwmon(struct memlat_hwmon *hw)
		{
		int cpu, ret = 0;
		@@ -280,13 +246,14 @@ static int start_hwmon(struct memlat_hwmon *hw)
		struct cpu_grp_info *cpu_grp = container_of(hw,
		struct cpu_grp_info, hw);

		register_cpu_notifier(&cpu_grp->arm_memlat_cpu_notif);

		get_online_cpus();
		for_each_cpu(cpu, &cpu_grp->cpus) {
		hw_data = &per_cpu(pm_data, cpu);
		ret = set_events(hw_data, cpu);
		if (ret) {
		if (!cpu_online(cpu)) {
		hotplug_notif_register();
		hw_data->init_pending = true;
		ret = 0;
		} else {
		@@ -337,6 +304,7 @@ static int arm_memlat_mon_driver_probe(struct platform_device *pdev)
		cpu_grp = devm_kzalloc(dev, sizeof(*cpu_grp), GFP_KERNEL);
		if (!cpu_grp)
		return -ENOMEM;
		cpu_grp->arm_memlat_cpu_notif.notifier_call = arm_memlat_cpu_callback;
		hw = &cpu_grp->hw;

		hw->dev = dev;