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Commit 56782550 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'pm-4.14-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm 

Pull power management fix from Rafael Wysocki:
 "This fixes a device power management quality of service (PM QoS)
  framework implementation issue causing 'no restriction' requests for
  device resume latency, including 'no restriction' set by user space,
  to effectively override requests with specific device resume latency
  requirements.

  It is late in the cycle, but the bug in question is in the 'user space
  can trigger unexpected behavior' category and the fix is
  stable-candidate, so here it goes"

* tag 'pm-4.14-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  PM / QoS: Fix device resume latency PM QoS
parents 3b5a9a8e 0cc2b4e5

Documentation/ABI/testing/sysfs-devices-power

+3 −1
Original line number Diff line number Diff line
@@ -211,7 +211,9 @@ Description: 
		device, after it has been suspended at run time, from a resume

		request to the moment the device will be ready to process I/O,

		in microseconds.  If it is equal to 0, however, this means that

		the PM QoS resume latency may be arbitrary.

		the PM QoS resume latency may be arbitrary and the special value

		"n/a" means that user space cannot accept any resume latency at

		all for the given device.



		Not all drivers support this attribute.  If it isn't supported,

		it is not present.

drivers/base/cpu.c

+2 −1
Original line number Diff line number Diff line
@@ -377,7 +377,8 @@ int register_cpu(struct cpu *cpu, int num) 


	per_cpu(cpu_sys_devices, num) = &cpu->dev;

	register_cpu_under_node(num, cpu_to_node(num));

	dev_pm_qos_expose_latency_limit(&cpu->dev, 0);

	dev_pm_qos_expose_latency_limit(&cpu->dev,

					PM_QOS_RESUME_LATENCY_NO_CONSTRAINT);



	return 0;

}

drivers/base/power/domain_governor.c

+30 −23
Original line number Diff line number Diff line
@@ -14,23 +14,20 @@ 
static int dev_update_qos_constraint(struct device *dev, void *data)

{

	s64 *constraint_ns_p = data;

	s32 constraint_ns = -1;

	s64 constraint_ns = -1;



	if (dev->power.subsys_data && dev->power.subsys_data->domain_data)

		constraint_ns = dev_gpd_data(dev)->td.effective_constraint_ns;



	if (constraint_ns < 0) {

	if (constraint_ns < 0)

		constraint_ns = dev_pm_qos_read_value(dev);

		constraint_ns *= NSEC_PER_USEC;

	}

	if (constraint_ns == 0)



	if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)

		return 0;



	/*

	 * constraint_ns cannot be negative here, because the device has been

	 * suspended.

	 */

	if (constraint_ns < *constraint_ns_p || *constraint_ns_p == 0)

	constraint_ns *= NSEC_PER_USEC;



	if (constraint_ns < *constraint_ns_p || *constraint_ns_p < 0)

		*constraint_ns_p = constraint_ns;



	return 0;
@@ -63,10 +60,14 @@ static bool default_suspend_ok(struct device *dev) 


	spin_unlock_irqrestore(&dev->power.lock, flags);



	if (constraint_ns < 0)

	if (constraint_ns == 0)

		return false;



	if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)

		constraint_ns = -1;

	else

		constraint_ns *= NSEC_PER_USEC;



	/*

	 * We can walk the children without any additional locking, because

	 * they all have been suspended at this point and their
@@ -76,14 +77,19 @@ static bool default_suspend_ok(struct device *dev) 
		device_for_each_child(dev, &constraint_ns,

				      dev_update_qos_constraint);



	if (constraint_ns < 0) {

		/* The children have no constraints. */

		td->effective_constraint_ns = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT;

		td->cached_suspend_ok = true;

	} else {

		constraint_ns -= td->suspend_latency_ns + td->resume_latency_ns;

		if (constraint_ns > 0) {

		constraint_ns -= td->suspend_latency_ns +

				td->resume_latency_ns;

		if (constraint_ns == 0)

			return false;

	}

			td->effective_constraint_ns = constraint_ns;

	td->cached_suspend_ok = constraint_ns >= 0;

			td->cached_suspend_ok = true;

		} else {

			td->effective_constraint_ns = 0;

		}

	}



	/*

	 * The children have been suspended already, so we don't need to take
@@ -145,13 +151,14 @@ static bool __default_power_down_ok(struct dev_pm_domain *pd, 
		td = &to_gpd_data(pdd)->td;

		constraint_ns = td->effective_constraint_ns;

		/* default_suspend_ok() need not be called before us. */

		if (constraint_ns < 0) {

		if (constraint_ns < 0)

			constraint_ns = dev_pm_qos_read_value(pdd->dev);

			constraint_ns *= NSEC_PER_USEC;

		}

		if (constraint_ns == 0)



		if (constraint_ns == PM_QOS_RESUME_LATENCY_NO_CONSTRAINT)

			continue;



		constraint_ns *= NSEC_PER_USEC;



		/*

		 * constraint_ns cannot be negative here, because the device has

		 * been suspended.

drivers/base/power/qos.c

+1 −1
Original line number Diff line number Diff line
@@ -189,7 +189,7 @@ static int dev_pm_qos_constraints_allocate(struct device *dev) 
	plist_head_init(&c->list);

	c->target_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;

	c->default_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;

	c->no_constraint_value = PM_QOS_RESUME_LATENCY_DEFAULT_VALUE;

	c->no_constraint_value = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT;

	c->type = PM_QOS_MIN;

	c->notifiers = n;

drivers/base/power/runtime.c

+1 −1
Original line number Diff line number Diff line
@@ -253,7 +253,7 @@ static int rpm_check_suspend_allowed(struct device *dev) 
	    || (dev->power.request_pending

			&& dev->power.request == RPM_REQ_RESUME))

		retval = -EAGAIN;

	else if (__dev_pm_qos_read_value(dev) < 0)

	else if (__dev_pm_qos_read_value(dev) == 0)

		retval = -EPERM;

	else if (dev->power.runtime_status == RPM_SUSPENDED)

		retval = 1;