Commit d8c216cf authored by Rafael J. Wysocki's avatar Rafael J. Wysocki Committed by Len Brown
Browse files

cpuidle: Make cpuidle_enable_device() call poll_idle_init() 



The following scenario is possible with the current cpuidle code and
the ACPI cpuidle driver:
(1) acpi_processor_cst_has_changed() is called,
(2) cpuidle_disable_device() is called,
(3) cpuidle_remove_state_sysfs() is called to remove the (presumably
    outdated) states info from sysfs,
(3) acpi_processor_get_power_info() is called, the first entry in the
    pr->power.states[] table is filled with zeros,
(4) acpi_processor_setup_cpuidle() is called and it doesn't fill the
    first entry in pr->power.states[],
(5) cpuidle_enable_device() is called,
(6) __cpuidle_register_device() is _not_ called, since the device has
    already been registered,
(7) Consequently, poll_idle_init() is _not_ called either,
(8) cpuidle_add_state_sysfs() is called to create the sysfs attributes
    for the new states and it uses the bogus first table entry from
    acpi_processor_get_power_info() for creating state0.

This problem is avoided if cpuidle_enable_device()
unconditionally calls poll_idle_init().

Reported-by: default avatarLen Brown <len.brown@intel.com>
Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
cc: stable@kernel.org
parent ddbd550d

drivers/cpuidle/cpuidle.c

+41 −41
Original line number Diff line number Diff line
@@ -154,6 +154,45 @@ void cpuidle_resume_and_unlock(void) 


EXPORT_SYMBOL_GPL(cpuidle_resume_and_unlock);



#ifdef CONFIG_ARCH_HAS_CPU_RELAX

static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st)

{

	ktime_t	t1, t2;

	s64 diff;

	int ret;



	t1 = ktime_get();

	local_irq_enable();

	while (!need_resched())

		cpu_relax();



	t2 = ktime_get();

	diff = ktime_to_us(ktime_sub(t2, t1));

	if (diff > INT_MAX)

		diff = INT_MAX;



	ret = (int) diff;

	return ret;

}



static void poll_idle_init(struct cpuidle_device *dev)

{

	struct cpuidle_state *state = &dev->states[0];



	cpuidle_set_statedata(state, NULL);



	snprintf(state->name, CPUIDLE_NAME_LEN, "C0");

	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");

	state->exit_latency = 0;

	state->target_residency = 0;

	state->power_usage = -1;

	state->flags = CPUIDLE_FLAG_POLL;

	state->enter = poll_idle;

}

#else

static void poll_idle_init(struct cpuidle_device *dev) {}

#endif /* CONFIG_ARCH_HAS_CPU_RELAX */



/**

 * cpuidle_enable_device - enables idle PM for a CPU

 * @dev: the CPU
@@ -178,6 +217,8 @@ int cpuidle_enable_device(struct cpuidle_device *dev) 
			return ret;

	}



	poll_idle_init(dev);



	if ((ret = cpuidle_add_state_sysfs(dev)))

		return ret;
@@ -232,45 +273,6 @@ void cpuidle_disable_device(struct cpuidle_device *dev) 


EXPORT_SYMBOL_GPL(cpuidle_disable_device);



#ifdef CONFIG_ARCH_HAS_CPU_RELAX

static int poll_idle(struct cpuidle_device *dev, struct cpuidle_state *st)

{

	ktime_t	t1, t2;

	s64 diff;

	int ret;



	t1 = ktime_get();

	local_irq_enable();

	while (!need_resched())

		cpu_relax();



	t2 = ktime_get();

	diff = ktime_to_us(ktime_sub(t2, t1));

	if (diff > INT_MAX)

		diff = INT_MAX;



	ret = (int) diff;

	return ret;

}



static void poll_idle_init(struct cpuidle_device *dev)

{

	struct cpuidle_state *state = &dev->states[0];



	cpuidle_set_statedata(state, NULL);



	snprintf(state->name, CPUIDLE_NAME_LEN, "C0");

	snprintf(state->desc, CPUIDLE_DESC_LEN, "CPUIDLE CORE POLL IDLE");

	state->exit_latency = 0;

	state->target_residency = 0;

	state->power_usage = -1;

	state->flags = CPUIDLE_FLAG_POLL;

	state->enter = poll_idle;

}

#else

static void poll_idle_init(struct cpuidle_device *dev) {}

#endif /* CONFIG_ARCH_HAS_CPU_RELAX */



/**

 * __cpuidle_register_device - internal register function called before register

 * and enable routines
@@ -291,8 +293,6 @@ static int __cpuidle_register_device(struct cpuidle_device *dev) 


	init_completion(&dev->kobj_unregister);



	poll_idle_init(dev);



	/*

	 * cpuidle driver should set the dev->power_specified bit

	 * before registering the device if the driver provides

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