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Date: Sun, 6 Feb 2011 19:54:30 +0100
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Minchan Kim <minchan.kim@...il.com>
Cc: Alan Stern <stern@...land.harvard.edu>,
LKML <linux-kernel@...r.kernel.org>,
Linux PM mailing list <linux-pm@...ts.linux-foundation.org>,
Greg KH <greg@...ah.com>
Subject: Re: [PATCH] PM: Do not create wakeup sysfs files for devices that cannot wake up (v2)
On Sunday, February 06, 2011, Minchan Kim wrote:
> On Sun, Feb 6, 2011 at 11:19 PM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> > Hi,
> >
> > Below is the next version of the patch changing the PM core to only create
> > wakeup sysfs files for devices that are wakeup-capable. It contains a change
> > in drivers/usb/core/hub.c that should avoid the problem described in the thread
> > at https://lkml.org/lkml/2011/2/5/108 , but I'm not 100% it's the right
> > approach. Please have a look.
> >
> > Thanks,
> > Rafael
> >
> >
> > ---
> > From: Rafael J. Wysocki <rjw@...k.pl>
> > Subject: PM: Don't create wakeup sysfs files for devices that can't wake up (v2)
> >
> > Currently, wakeup sysfs attributes are created for all devices,
> > regardless of whether or not they are wakeup-capable. This is
> > excessive and complicates wakeup device identification from user
> > space (i.e. to identify wakeup-capable devices user space has to read
> > /sys/devices/.../power/wakeup for all devices and see if they are not
> > empty).
> >
> > Fix this issue by avoiding to create wakeup sysfs files for devices
> > that cannot wake up the system from sleep states (i.e. whose
> > power.can_wakeup flags are unset during registration) and modify
> > device_set_wakeup_capable() so that it adds (or removes) the relevant
> > sysfs attributes if a device's wakeup capability status is changed.
> >
> > Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
> > ---
> > Documentation/ABI/testing/sysfs-devices-power | 20 +++---
> > Documentation/power/devices.txt | 20 +++---
> > drivers/base/power/power.h | 21 +++----
> > drivers/base/power/sysfs.c | 78 +++++++++++++++++---------
> > drivers/base/power/wakeup.c | 26 ++++++++
> > drivers/usb/core/hub.c | 10 ++-
> > include/linux/pm_runtime.h | 6 ++
> > include/linux/pm_wakeup.h | 10 ---
> > 8 files changed, 121 insertions(+), 70 deletions(-)
> >
> > Index: linux-2.6/drivers/base/power/sysfs.c
> > ===================================================================
> > --- linux-2.6.orig/drivers/base/power/sysfs.c
> > +++ linux-2.6/drivers/base/power/sysfs.c
> > @@ -431,26 +431,18 @@ static ssize_t async_store(struct device
> > static DEVICE_ATTR(async, 0644, async_show, async_store);
> > #endif /* CONFIG_PM_ADVANCED_DEBUG */
> >
> > -static struct attribute * power_attrs[] = {
> > - &dev_attr_wakeup.attr,
> > -#ifdef CONFIG_PM_SLEEP
> > - &dev_attr_wakeup_count.attr,
> > - &dev_attr_wakeup_active_count.attr,
> > - &dev_attr_wakeup_hit_count.attr,
> > - &dev_attr_wakeup_active.attr,
> > - &dev_attr_wakeup_total_time_ms.attr,
> > - &dev_attr_wakeup_max_time_ms.attr,
> > - &dev_attr_wakeup_last_time_ms.attr,
> > -#endif
> > +static struct attribute *power_attrs[] = {
> > #ifdef CONFIG_PM_ADVANCED_DEBUG
> > +#ifdef CONFIG_PM_SLEEP
> > &dev_attr_async.attr,
> > +#endif
> > #ifdef CONFIG_PM_RUNTIME
> > &dev_attr_runtime_status.attr,
> > &dev_attr_runtime_usage.attr,
> > &dev_attr_runtime_active_kids.attr,
> > &dev_attr_runtime_enabled.attr,
> > #endif
> > -#endif
> > +#endif /* CONFIG_PM_ADVANCED_DEBUG */
> > NULL,
> > };
> > static struct attribute_group pm_attr_group = {
> > @@ -458,9 +450,26 @@ static struct attribute_group pm_attr_gr
> > .attrs = power_attrs,
> > };
> >
> > -#ifdef CONFIG_PM_RUNTIME
> > +static struct attribute *wakeup_attrs[] = {
> > +#ifdef CONFIG_PM_SLEEP
> > + &dev_attr_wakeup.attr,
> > + &dev_attr_wakeup_count.attr,
> > + &dev_attr_wakeup_active_count.attr,
> > + &dev_attr_wakeup_hit_count.attr,
> > + &dev_attr_wakeup_active.attr,
> > + &dev_attr_wakeup_total_time_ms.attr,
> > + &dev_attr_wakeup_max_time_ms.attr,
> > + &dev_attr_wakeup_last_time_ms.attr,
> > +#endif
> > + NULL,
> > +};
> > +static struct attribute_group pm_wakeup_attr_group = {
> > + .name = power_group_name,
> > + .attrs = wakeup_attrs,
> > +};
> >
> > static struct attribute *runtime_attrs[] = {
> > +#ifdef CONFIG_PM_RUNTIME
> > #ifndef CONFIG_PM_ADVANCED_DEBUG
> > &dev_attr_runtime_status.attr,
> > #endif
> > @@ -468,6 +477,7 @@ static struct attribute *runtime_attrs[]
> > &dev_attr_runtime_suspended_time.attr,
> > &dev_attr_runtime_active_time.attr,
> > &dev_attr_autosuspend_delay_ms.attr,
> > +#endif /* CONFIG_PM_RUNTIME */
> > NULL,
> > };
> > static struct attribute_group pm_runtime_attr_group = {
> > @@ -480,35 +490,49 @@ int dpm_sysfs_add(struct device *dev)
> > int rc;
> >
> > rc = sysfs_create_group(&dev->kobj, &pm_attr_group);
> > - if (rc == 0 && !dev->power.no_callbacks) {
> > + if (rc)
> > + return rc;
> > +
> > + if (pm_runtime_callbacks_present(dev)) {
> > rc = sysfs_merge_group(&dev->kobj, &pm_runtime_attr_group);
> > if (rc)
> > - sysfs_remove_group(&dev->kobj, &pm_attr_group);
> > + goto err_out;
> > + }
> > +
> > + if (device_can_wakeup(dev)) {
> > + rc = sysfs_merge_group(&dev->kobj, &pm_wakeup_attr_group);
> > + if (rc) {
> > + if (pm_runtime_callbacks_present(dev))
> > + sysfs_unmerge_group(&dev->kobj,
> > + &pm_runtime_attr_group);
> > + goto err_out;
> > + }
> > }
> > + return 0;
> > +
> > + err_out:
> > + sysfs_remove_group(&dev->kobj, &pm_attr_group);
> > return rc;
> > }
> >
> > -void rpm_sysfs_remove(struct device *dev)
> > +int wakeup_sysfs_add(struct device *dev)
> > {
> > - sysfs_unmerge_group(&dev->kobj, &pm_runtime_attr_group);
> > + return sysfs_merge_group(&dev->kobj, &pm_wakeup_attr_group);
> > }
> >
> > -void dpm_sysfs_remove(struct device *dev)
> > +void wakeup_sysfs_remove(struct device *dev)
> > {
> > - rpm_sysfs_remove(dev);
> > - sysfs_remove_group(&dev->kobj, &pm_attr_group);
> > + sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group);
> > }
> >
> > -#else /* CONFIG_PM_RUNTIME */
> > -
> > -int dpm_sysfs_add(struct device * dev)
> > +void rpm_sysfs_remove(struct device *dev)
> > {
> > - return sysfs_create_group(&dev->kobj, &pm_attr_group);
> > + sysfs_unmerge_group(&dev->kobj, &pm_runtime_attr_group);
> > }
> >
> > -void dpm_sysfs_remove(struct device * dev)
> > +void dpm_sysfs_remove(struct device *dev)
> > {
> > + rpm_sysfs_remove(dev);
> > + sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group);
> > sysfs_remove_group(&dev->kobj, &pm_attr_group);
> > }
> > -
> > -#endif
> > Index: linux-2.6/include/linux/pm_runtime.h
> > ===================================================================
> > --- linux-2.6.orig/include/linux/pm_runtime.h
> > +++ linux-2.6/include/linux/pm_runtime.h
> > @@ -87,6 +87,11 @@ static inline bool pm_runtime_enabled(st
> > return !dev->power.disable_depth;
> > }
> >
> > +static inline bool pm_runtime_callbacks_present(struct device *dev)
> > +{
> > + return !dev->power.no_callbacks;
> > +}
> > +
> > static inline void pm_runtime_mark_last_busy(struct device *dev)
> > {
> > ACCESS_ONCE(dev->power.last_busy) = jiffies;
> > @@ -133,6 +138,7 @@ static inline int pm_generic_runtime_res
> > static inline void pm_runtime_no_callbacks(struct device *dev) {}
> > static inline void pm_runtime_irq_safe(struct device *dev) {}
> >
> > +static inline bool pm_runtime_callbacks_present(struct device *dev) { return false; }
> > static inline void pm_runtime_mark_last_busy(struct device *dev) {}
> > static inline void __pm_runtime_use_autosuspend(struct device *dev,
> > bool use) {}
> > Index: linux-2.6/drivers/base/power/power.h
> > ===================================================================
> > --- linux-2.6.orig/drivers/base/power/power.h
> > +++ linux-2.6/drivers/base/power/power.h
> > @@ -58,19 +58,18 @@ static inline void device_pm_move_last(s
> > * sysfs.c
> > */
> >
> > -extern int dpm_sysfs_add(struct device *);
> > -extern void dpm_sysfs_remove(struct device *);
> > -extern void rpm_sysfs_remove(struct device *);
> > +extern int dpm_sysfs_add(struct device *dev);
> > +extern void dpm_sysfs_remove(struct device *dev);
> > +extern void rpm_sysfs_remove(struct device *dev);
> > +extern int wakeup_sysfs_add(struct device *dev);
> > +extern void wakeup_sysfs_remove(struct device *dev);
> >
> > #else /* CONFIG_PM */
> >
> > -static inline int dpm_sysfs_add(struct device *dev)
> > -{
> > - return 0;
> > -}
> > -
> > -static inline void dpm_sysfs_remove(struct device *dev)
> > -{
> > -}
> > +static inline int dpm_sysfs_add(struct device *dev) { return 0; }
> > +static inline void dpm_sysfs_remove(struct device *dev) {}
> > +static inline void rpm_sysfs_remove(struct device *dev) {}
> > +static inline int wakeup_sysfs_add(struct device *dev) { return 0; }
> > +static inline void wakeup_sysfs_remove(struct device *dev) {}
> >
> > #endif
> > Index: linux-2.6/include/linux/pm_wakeup.h
> > ===================================================================
> > --- linux-2.6.orig/include/linux/pm_wakeup.h
> > +++ linux-2.6/include/linux/pm_wakeup.h
> > @@ -62,18 +62,11 @@ struct wakeup_source {
> > * Changes to device_may_wakeup take effect on the next pm state change.
> > */
> >
> > -static inline void device_set_wakeup_capable(struct device *dev, bool capable)
> > -{
> > - dev->power.can_wakeup = capable;
> > -}
> > -
> > static inline bool device_can_wakeup(struct device *dev)
> > {
> > return dev->power.can_wakeup;
> > }
> >
> > -
> > -
> > static inline bool device_may_wakeup(struct device *dev)
> > {
> > return dev->power.can_wakeup && !!dev->power.wakeup;
> > @@ -88,6 +81,7 @@ extern struct wakeup_source *wakeup_sour
> > extern void wakeup_source_unregister(struct wakeup_source *ws);
> > extern int device_wakeup_enable(struct device *dev);
> > extern int device_wakeup_disable(struct device *dev);
> > +extern void device_set_wakeup_capable(struct device *dev, bool capable);
> > extern int device_init_wakeup(struct device *dev, bool val);
> > extern int device_set_wakeup_enable(struct device *dev, bool enable);
> > extern void __pm_stay_awake(struct wakeup_source *ws);
> > @@ -144,7 +138,7 @@ static inline int device_wakeup_disable(
> >
> > static inline int device_init_wakeup(struct device *dev, bool val)
> > {
> > - dev->power.can_wakeup = val;
> > + device_set_wakeup_capable(dev, val);
> > return val ? -EINVAL : 0;
> > }
> >
> > Index: linux-2.6/drivers/base/power/wakeup.c
> > ===================================================================
> > --- linux-2.6.orig/drivers/base/power/wakeup.c
> > +++ linux-2.6/drivers/base/power/wakeup.c
> > @@ -242,6 +242,32 @@ int device_wakeup_disable(struct device
> > EXPORT_SYMBOL_GPL(device_wakeup_disable);
> >
> > /**
> > + * device_set_wakeup_capable - Set/reset device wakeup capability flag.
> > + * @dev: Device to handle.
> > + * @capable: Whether or not @dev is capable of waking up the system from sleep.
> > + *
> > + * If @capable is set, set the @dev's power.can_wakeup flag and add its
> > + * wakeup-related attributes to sysfs. Otherwise, unset the @dev's
> > + * power.can_wakeup flag and remove its wakeup-related attributes from sysfs.
> > + */
> > +void device_set_wakeup_capable(struct device *dev, bool capable)
> > +{
> > + if (!!dev->power.can_wakeup == !!capable)
> > + return;
> > +
> > + if (device_is_registered(dev)) {
> > + if (capable) {
> > + if (wakeup_sysfs_add(dev))
> > + return;
> > + } else {
> > + wakeup_sysfs_remove(dev);
> > + }
> > + }
> > + dev->power.can_wakeup = capable;
> > +}
> > +EXPORT_SYMBOL_GPL(device_set_wakeup_capable);
> > +
> > +/**
> > * device_init_wakeup - Device wakeup initialization.
> > * @dev: Device to handle.
> > * @enable: Whether or not to enable @dev as a wakeup device.
> > Index: linux-2.6/Documentation/power/devices.txt
> > ===================================================================
> > --- linux-2.6.orig/Documentation/power/devices.txt
> > +++ linux-2.6/Documentation/power/devices.txt
> > @@ -159,18 +159,18 @@ matter, and the kernel is responsible fo
> > whether or not a wakeup-capable device should issue wakeup events is a policy
> > decision, and it is managed by user space through a sysfs attribute: the
> > power/wakeup file. User space can write the strings "enabled" or "disabled" to
> > -set or clear the should_wakeup flag, respectively. Reads from the file will
> > -return the corresponding string if can_wakeup is true, but if can_wakeup is
> > -false then reads will return an empty string, to indicate that the device
> > -doesn't support wakeup events. (But even though the file appears empty, writes
> > -will still affect the should_wakeup flag.)
> > +set or clear the "should_wakeup" flag, respectively. This file is only present
> > +for wakeup-capable devices (i.e. devices whose "can_wakeup" flags are set)
> > +and is created (or removed) by device_set_wakeup_capable(). Reads from the
> > +file will return the corresponding string.
> >
> > The device_may_wakeup() routine returns true only if both flags are set.
> > -Drivers should check this routine when putting devices in a low-power state
> > -during a system sleep transition, to see whether or not to enable the devices'
> > -wakeup mechanisms. However for runtime power management, wakeup events should
> > -be enabled whenever the device and driver both support them, regardless of the
> > -should_wakeup flag.
> > +This information is used by subsystems, like the PCI bus type code, to see
> > +whether or not to enable the devices' wakeup mechanisms. If device wakeup
> > +mechanisms are enabled or disabled directly by drivers, they also should use
> > +device_may_wakeup() to decide what to do during a system sleep transition.
> > +However for runtime power management, wakeup events should be enabled whenever
> > +the device and driver both support them, regardless of the should_wakeup flag.
> >
> >
> > /sys/devices/.../power/control files
> > Index: linux-2.6/Documentation/ABI/testing/sysfs-devices-power
> > ===================================================================
> > --- linux-2.6.orig/Documentation/ABI/testing/sysfs-devices-power
> > +++ linux-2.6/Documentation/ABI/testing/sysfs-devices-power
> > @@ -29,9 +29,8 @@ Description:
> > "disabled" to it.
> >
> > For the devices that are not capable of generating system wakeup
> > - events this file contains "\n". In that cases the user space
> > - cannot modify the contents of this file and the device cannot be
> > - enabled to wake up the system.
> > + events this file is not present. In that case the device cannot
> > + be enabled to wake up the system from sleep states.
> >
> > What: /sys/devices/.../power/control
> > Date: January 2009
> > @@ -85,7 +84,7 @@ Description:
> > The /sys/devices/.../wakeup_count attribute contains the number
> > of signaled wakeup events associated with the device. This
> > attribute is read-only. If the device is not enabled to wake up
> > - the system from sleep states, this attribute is empty.
> > + the system from sleep states, this attribute is not present.
> >
> > What: /sys/devices/.../power/wakeup_active_count
> > Date: September 2010
> > @@ -95,7 +94,7 @@ Description:
> > number of times the processing of wakeup events associated with
> > the device was completed (at the kernel level). This attribute
> > is read-only. If the device is not enabled to wake up the
> > - system from sleep states, this attribute is empty.
> > + system from sleep states, this attribute is not present.
> >
> > What: /sys/devices/.../power/wakeup_hit_count
> > Date: September 2010
> > @@ -105,7 +104,8 @@ Description:
> > number of times the processing of a wakeup event associated with
> > the device might prevent the system from entering a sleep state.
> > This attribute is read-only. If the device is not enabled to
> > - wake up the system from sleep states, this attribute is empty.
> > + wake up the system from sleep states, this attribute is not
> > + present.
> >
> > What: /sys/devices/.../power/wakeup_active
> > Date: September 2010
> > @@ -115,7 +115,7 @@ Description:
> > or 0, depending on whether or not a wakeup event associated with
> > the device is being processed (1). This attribute is read-only.
> > If the device is not enabled to wake up the system from sleep
> > - states, this attribute is empty.
> > + states, this attribute is not present.
> >
> > What: /sys/devices/.../power/wakeup_total_time_ms
> > Date: September 2010
> > @@ -125,7 +125,7 @@ Description:
> > the total time of processing wakeup events associated with the
> > device, in milliseconds. This attribute is read-only. If the
> > device is not enabled to wake up the system from sleep states,
> > - this attribute is empty.
> > + this attribute is not present.
> >
> > What: /sys/devices/.../power/wakeup_max_time_ms
> > Date: September 2010
> > @@ -135,7 +135,7 @@ Description:
> > the maximum time of processing a single wakeup event associated
> > with the device, in milliseconds. This attribute is read-only.
> > If the device is not enabled to wake up the system from sleep
> > - states, this attribute is empty.
> > + states, this attribute is not present.
> >
> > What: /sys/devices/.../power/wakeup_last_time_ms
> > Date: September 2010
> > @@ -146,7 +146,7 @@ Description:
> > signaling the last wakeup event associated with the device, in
> > milliseconds. This attribute is read-only. If the device is
> > not enabled to wake up the system from sleep states, this
> > - attribute is empty.
> > + attribute is not present.
> >
> > What: /sys/devices/.../power/autosuspend_delay_ms
> > Date: September 2010
> > Index: linux-2.6/drivers/usb/core/hub.c
> > ===================================================================
> > --- linux-2.6.orig/drivers/usb/core/hub.c
> > +++ linux-2.6/drivers/usb/core/hub.c
> > @@ -1465,6 +1465,7 @@ void usb_set_device_state(struct usb_dev
> > enum usb_device_state new_state)
> > {
> > unsigned long flags;
> > + int wakeup = -1;
> >
> > spin_lock_irqsave(&device_state_lock, flags);
> > if (udev->state == USB_STATE_NOTATTACHED)
> > @@ -1479,11 +1480,10 @@ void usb_set_device_state(struct usb_dev
> > || new_state == USB_STATE_SUSPENDED)
> > ; /* No change to wakeup settings */
> > else if (new_state == USB_STATE_CONFIGURED)
> > - device_set_wakeup_capable(&udev->dev,
> > - (udev->actconfig->desc.bmAttributes
> > - & USB_CONFIG_ATT_WAKEUP));
> > + wakeup = udev->actconfig->desc.bmAttributes
> > + & USB_CONFIG_ATT_WAKEUP;
> > else
> > - device_set_wakeup_capable(&udev->dev, 0);
> > + wakeup = 0;
> > }
> > if (udev->state == USB_STATE_SUSPENDED &&
> > new_state != USB_STATE_SUSPENDED)
> > @@ -1495,6 +1495,8 @@ void usb_set_device_state(struct usb_dev
> > } else
> > recursively_mark_NOTATTACHED(udev);
> > spin_unlock_irqrestore(&device_state_lock, flags);
> > + if (wakeup >= 0)
> > + device_set_wakeup_capable(&udev->dev, wakeup);
> > }
> > EXPORT_SYMBOL_GPL(usb_set_device_state);
> >
> >
>
> I can't say the work of usb since I am not a expert about that.
> Anyway, the patch works well in my machine.
> Just a nitpick.
>
> Please, add a kind comment for new exported device_set_wakeup_capable
> to show the function should be called by process context.
Will do.
> Feel free to use below signs.
>
> Reported-by: Minchan Kim <minchan.kim@...il.com>
> Tested-by: Minchan Kim <minchan.kim@...il.com>
Thanks,
Rafael
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