Commit 9b6a3f36 authored by Mike Leach's avatar Mike Leach Committed by Greg Kroah-Hartman
Browse files

coresight: etmv4: Fix CPU power management setup in probe() function 



The current probe() function calls a pair of cpuhp_xxx API functions to
setup CPU hotplug handling. The hotplug lock is held for the duration of
the two calls and other CPU related code using cpus_read_lock() /
cpus_read_unlock() calls.

The problem is that on error states, goto: statements bypass the
cpus_read_unlock() call. This code has increased in complexity as the
driver has developed.

This patch introduces a pair of helper functions etm4_pm_setup_cpuslocked()
and etm4_pm_clear() which correct the issues above and group the PM code a
little better.

The two functions etm4_cpu_pm_register() and etm4_cpu_pm_unregister() are
dropped as these call cpu_pm_register_notifier() / ..unregister_notifier()
dependent on CONFIG_CPU_PM - but this define is used to nop these functions
out in the pm headers - so the wrapper functions are superfluous.

Fixes: f188b5e7 ("coresight: etm4x: Save/restore state across CPU low power states")
Fixes: e9f5d63f ("hwtracing/coresight-etm4x: Use cpuhp_setup_state_nocalls_cpuslocked()")
Fixes: 58eb457b ("hwtracing/coresight-etm4x: Convert to hotplug state machine")
Signed-off-by: default avatarMike Leach <mike.leach@linaro.org>
Cc: stable <stable@vger.kernel.org>
Reviewed-by: default avatarMathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200701160852.2782823-3-mathieu.poirier@linaro.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6740de94

drivers/hwtracing/coresight/coresight-etm4x.c

+53 −29
Original line number Diff line number Diff line
@@ -1388,18 +1388,57 @@ static struct notifier_block etm4_cpu_pm_nb = { 
	.notifier_call = etm4_cpu_pm_notify,

};



static int etm4_cpu_pm_register(void)

/* Setup PM. Called with cpus locked. Deals with error conditions and counts */

static int etm4_pm_setup_cpuslocked(void)

{

	if (IS_ENABLED(CONFIG_CPU_PM))

		return cpu_pm_register_notifier(&etm4_cpu_pm_nb);

	int ret;



	if (etm4_count++)

		return 0;



	ret = cpu_pm_register_notifier(&etm4_cpu_pm_nb);

	if (ret)

		goto reduce_count;



	ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ARM_CORESIGHT_STARTING,

						   "arm/coresight4:starting",

						   etm4_starting_cpu, etm4_dying_cpu);



	if (ret)

		goto unregister_notifier;



	ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ONLINE_DYN,

						   "arm/coresight4:online",

						   etm4_online_cpu, NULL);



	/* HP dyn state ID returned in ret on success */

	if (ret > 0) {

		hp_online = ret;

		return 0;

	}



static void etm4_cpu_pm_unregister(void)

	/* failed dyn state - remove others */

	cpuhp_remove_state_nocalls_cpuslocked(CPUHP_AP_ARM_CORESIGHT_STARTING);



unregister_notifier:

	cpu_pm_unregister_notifier(&etm4_cpu_pm_nb);



reduce_count:

	--etm4_count;

	return ret;

}



static void etm4_pm_clear(void)

{

	if (IS_ENABLED(CONFIG_CPU_PM))

	if (--etm4_count != 0)

		return;



	cpu_pm_unregister_notifier(&etm4_cpu_pm_nb);

	cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING);

	if (hp_online) {

		cpuhp_remove_state_nocalls(hp_online);

		hp_online = 0;

	}

}



static int etm4_probe(struct amba_device *adev, const struct amba_id *id)
@@ -1453,24 +1492,15 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id) 
				etm4_init_arch_data,  drvdata, 1))

		dev_err(dev, "ETM arch init failed\n");



	if (!etm4_count++) {

		cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ARM_CORESIGHT_STARTING,

						     "arm/coresight4:starting",

						     etm4_starting_cpu, etm4_dying_cpu);

		ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ONLINE_DYN,

							   "arm/coresight4:online",

							   etm4_online_cpu, NULL);

		if (ret < 0)

			goto err_arch_supported;

		hp_online = ret;

	ret = etm4_pm_setup_cpuslocked();

	cpus_read_unlock();



		ret = etm4_cpu_pm_register();

		if (ret)

			goto err_arch_supported;

	/* etm4_pm_setup_cpuslocked() does its own cleanup - exit on error */

	if (ret) {

		etmdrvdata[drvdata->cpu] = NULL;

		return ret;

	}



	cpus_read_unlock();



	if (etm4_arch_supported(drvdata->arch) == false) {

		ret = -EINVAL;

		goto err_arch_supported;
@@ -1517,13 +1547,7 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id) 


err_arch_supported:

	etmdrvdata[drvdata->cpu] = NULL;

	if (--etm4_count == 0) {

		etm4_cpu_pm_unregister();



		cpuhp_remove_state_nocalls(CPUHP_AP_ARM_CORESIGHT_STARTING);

		if (hp_online)

			cpuhp_remove_state_nocalls(hp_online);

	}

	etm4_pm_clear();

	return ret;

}

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