Udev rules that depend on the power/wakeup attribute don't get triggered
correctly if device_set_wakeup_capable is called after the device is
created. This can happen for several reasons (driver sets wakeup after
device is created, wakeup is changed on parent device, etc) and it seems
reasonable to emit a changed event when adding or removing attributes on
the device.
Signed-off-by: Abhishek Pandit-Subedi <[email protected]>
---
Changes in v4:
- Fix warning where returning from void and tested on device
Changes in v3:
- Simplified error handling
Changes in v2:
- Add newline at end of bt_dev_err
drivers/base/power/sysfs.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index 24d25cf8ab1487..aeb58d40aac8de 100644
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
/* sysfs entries for device PM */
#include <linux/device.h>
+#include <linux/kobject.h>
#include <linux/string.h>
#include <linux/export.h>
#include <linux/pm_qos.h>
@@ -739,12 +740,18 @@ int dpm_sysfs_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
int wakeup_sysfs_add(struct device *dev)
{
- return sysfs_merge_group(&dev->kobj, &pm_wakeup_attr_group);
+ int ret = sysfs_merge_group(&dev->kobj, &pm_wakeup_attr_group);
+
+ if (ret)
+ return ret;
+
+ return kobject_uevent(&dev->kobj, KOBJ_CHANGE);
}
void wakeup_sysfs_remove(struct device *dev)
{
sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group);
+ kobject_uevent(&dev->kobj, KOBJ_CHANGE);
}
int pm_qos_sysfs_add_resume_latency(struct device *dev)
--
2.27.0.212.ge8ba1cc988-goog
Hi Rafael,
(resent in plain text)
On Tue, Jul 7, 2020 at 9:28 AM Rafael J. Wysocki <[email protected]> wrote:
>
> On Tue, Jul 7, 2020 at 6:24 PM Abhishek Pandit-Subedi
> <[email protected]> wrote:
> >
> > Udev rules that depend on the power/wakeup attribute don't get triggered
> > correctly if device_set_wakeup_capable is called after the device is
> > created. This can happen for several reasons (driver sets wakeup after
> > device is created, wakeup is changed on parent device, etc) and it seems
> > reasonable to emit a changed event when adding or removing attributes on
> > the device.
> >
> > Signed-off-by: Abhishek Pandit-Subedi <[email protected]>
> > ---
> >
> > Changes in v4:
> > - Fix warning where returning from void and tested on device
> >
> > Changes in v3:
> > - Simplified error handling
> >
> > Changes in v2:
> > - Add newline at end of bt_dev_err
> >
> > drivers/base/power/sysfs.c | 9 ++++++++-
> > 1 file changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
> > index 24d25cf8ab1487..aeb58d40aac8de 100644
> > --- a/drivers/base/power/sysfs.c
> > +++ b/drivers/base/power/sysfs.c
> > @@ -1,6 +1,7 @@
> > // SPDX-License-Identifier: GPL-2.0
> > /* sysfs entries for device PM */
> > #include <linux/device.h>
> > +#include <linux/kobject.h>
> > #include <linux/string.h>
> > #include <linux/export.h>
> > #include <linux/pm_qos.h>
> > @@ -739,12 +740,18 @@ int dpm_sysfs_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
> >
> > int wakeup_sysfs_add(struct device *dev)
> > {
> > - return sysfs_merge_group(&dev->kobj, &pm_wakeup_attr_group);
> > + int ret = sysfs_merge_group(&dev->kobj, &pm_wakeup_attr_group);
> > +
> > + if (ret)
> > + return ret;
> > +
> > + return kobject_uevent(&dev->kobj, KOBJ_CHANGE);
>
> So let me repeat the previous comment:
>
> If you return an error here, it may confuse the caller to think that
> the operation has failed completely, whereas the merging of the
> attribute group has been successful already.
>
> I don't think that an error can be returned at this point.
>
The caller looks at the return code and just logs that an error
occurred (no other action). It's also unlikely for kobject_uevent to
fail (I saw mostly -ENOMEM and an -ENOENT when the kobj wasn't in the
correct set).
Call site:
int ret = wakeup_sysfs_add(dev);
if (ret)
dev_info(dev, "Wakeup sysfs attributes not added\n");
So I'm ok with either keeping this as-is (caller isn't getting
confused, just logging) or swallowing the return of kobject_uevent.
> > }
> >
> > void wakeup_sysfs_remove(struct device *dev)
> > {
> > sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group);
> > + kobject_uevent(&dev->kobj, KOBJ_CHANGE);
> > }
> >
> > int pm_qos_sysfs_add_resume_latency(struct device *dev)
> > --
> > 2.27.0.212.ge8ba1cc988-goog
> >
On Tue, Jul 7, 2020 at 6:48 PM Abhishek Pandit-Subedi
<[email protected]> wrote:
>
> Hi Rafael,
>
> (resent in plain text)
>
> On Tue, Jul 7, 2020 at 9:28 AM Rafael J. Wysocki <[email protected]> wrote:
> >
> > On Tue, Jul 7, 2020 at 6:24 PM Abhishek Pandit-Subedi
> > <[email protected]> wrote:
> > >
> > > Udev rules that depend on the power/wakeup attribute don't get triggered
> > > correctly if device_set_wakeup_capable is called after the device is
> > > created. This can happen for several reasons (driver sets wakeup after
> > > device is created, wakeup is changed on parent device, etc) and it seems
> > > reasonable to emit a changed event when adding or removing attributes on
> > > the device.
> > >
> > > Signed-off-by: Abhishek Pandit-Subedi <[email protected]>
> > > ---
> > >
> > > Changes in v4:
> > > - Fix warning where returning from void and tested on device
> > >
> > > Changes in v3:
> > > - Simplified error handling
> > >
> > > Changes in v2:
> > > - Add newline at end of bt_dev_err
> > >
> > > drivers/base/power/sysfs.c | 9 ++++++++-
> > > 1 file changed, 8 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
> > > index 24d25cf8ab1487..aeb58d40aac8de 100644
> > > --- a/drivers/base/power/sysfs.c
> > > +++ b/drivers/base/power/sysfs.c
> > > @@ -1,6 +1,7 @@
> > > // SPDX-License-Identifier: GPL-2.0
> > > /* sysfs entries for device PM */
> > > #include <linux/device.h>
> > > +#include <linux/kobject.h>
> > > #include <linux/string.h>
> > > #include <linux/export.h>
> > > #include <linux/pm_qos.h>
> > > @@ -739,12 +740,18 @@ int dpm_sysfs_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
> > >
> > > int wakeup_sysfs_add(struct device *dev)
> > > {
> > > - return sysfs_merge_group(&dev->kobj, &pm_wakeup_attr_group);
> > > + int ret = sysfs_merge_group(&dev->kobj, &pm_wakeup_attr_group);
> > > +
> > > + if (ret)
> > > + return ret;
> > > +
> > > + return kobject_uevent(&dev->kobj, KOBJ_CHANGE);
> >
> > So let me repeat the previous comment:
> >
> > If you return an error here, it may confuse the caller to think that
> > the operation has failed completely, whereas the merging of the
> > attribute group has been successful already.
> >
> > I don't think that an error can be returned at this point.
> >
>
> The caller looks at the return code and just logs that an error
> occurred (no other action). It's also unlikely for kobject_uevent to
> fail (I saw mostly -ENOMEM and an -ENOENT when the kobj wasn't in the
> correct set).
>
> Call site:
> int ret = wakeup_sysfs_add(dev);
>
> if (ret)
> dev_info(dev, "Wakeup sysfs attributes not added\n");
Yes, which is confusing, because the wakeup attributes may in fact
have been added. Which is my point.
>
> So I'm ok with either keeping this as-is (caller isn't getting
> confused, just logging) or swallowing the return of kobject_uevent.
I would just ignore the return value of kobject_uevent() along the
lines of wakeup_sysfs_remove() below.
Thanks!
> > > }
> > >
> > > void wakeup_sysfs_remove(struct device *dev)
> > > {
> > > sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group);
> > > + kobject_uevent(&dev->kobj, KOBJ_CHANGE);
> > > }
> > >
> > > int pm_qos_sysfs_add_resume_latency(struct device *dev)
> > > --
> > > 2.27.0.212.ge8ba1cc988-goog
> > >
Sounds good to me. Patch v5 incoming after compile-test.
Thanks
Abhishek
On Tue, Jul 7, 2020 at 10:16 AM Rafael J. Wysocki <[email protected]> wrote:
>
> On Tue, Jul 7, 2020 at 6:48 PM Abhishek Pandit-Subedi
> <[email protected]> wrote:
> >
> > Hi Rafael,
> >
> > (resent in plain text)
> >
> > On Tue, Jul 7, 2020 at 9:28 AM Rafael J. Wysocki <[email protected]> wrote:
> > >
> > > On Tue, Jul 7, 2020 at 6:24 PM Abhishek Pandit-Subedi
> > > <[email protected]> wrote:
> > > >
> > > > Udev rules that depend on the power/wakeup attribute don't get triggered
> > > > correctly if device_set_wakeup_capable is called after the device is
> > > > created. This can happen for several reasons (driver sets wakeup after
> > > > device is created, wakeup is changed on parent device, etc) and it seems
> > > > reasonable to emit a changed event when adding or removing attributes on
> > > > the device.
> > > >
> > > > Signed-off-by: Abhishek Pandit-Subedi <[email protected]>
> > > > ---
> > > >
> > > > Changes in v4:
> > > > - Fix warning where returning from void and tested on device
> > > >
> > > > Changes in v3:
> > > > - Simplified error handling
> > > >
> > > > Changes in v2:
> > > > - Add newline at end of bt_dev_err
> > > >
> > > > drivers/base/power/sysfs.c | 9 ++++++++-
> > > > 1 file changed, 8 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
> > > > index 24d25cf8ab1487..aeb58d40aac8de 100644
> > > > --- a/drivers/base/power/sysfs.c
> > > > +++ b/drivers/base/power/sysfs.c
> > > > @@ -1,6 +1,7 @@
> > > > // SPDX-License-Identifier: GPL-2.0
> > > > /* sysfs entries for device PM */
> > > > #include <linux/device.h>
> > > > +#include <linux/kobject.h>
> > > > #include <linux/string.h>
> > > > #include <linux/export.h>
> > > > #include <linux/pm_qos.h>
> > > > @@ -739,12 +740,18 @@ int dpm_sysfs_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
> > > >
> > > > int wakeup_sysfs_add(struct device *dev)
> > > > {
> > > > - return sysfs_merge_group(&dev->kobj, &pm_wakeup_attr_group);
> > > > + int ret = sysfs_merge_group(&dev->kobj, &pm_wakeup_attr_group);
> > > > +
> > > > + if (ret)
> > > > + return ret;
> > > > +
> > > > + return kobject_uevent(&dev->kobj, KOBJ_CHANGE);
> > >
> > > So let me repeat the previous comment:
> > >
> > > If you return an error here, it may confuse the caller to think that
> > > the operation has failed completely, whereas the merging of the
> > > attribute group has been successful already.
> > >
> > > I don't think that an error can be returned at this point.
> > >
> >
> > The caller looks at the return code and just logs that an error
> > occurred (no other action). It's also unlikely for kobject_uevent to
> > fail (I saw mostly -ENOMEM and an -ENOENT when the kobj wasn't in the
> > correct set).
> >
> > Call site:
> > int ret = wakeup_sysfs_add(dev);
> >
> > if (ret)
> > dev_info(dev, "Wakeup sysfs attributes not added\n");
>
> Yes, which is confusing, because the wakeup attributes may in fact
> have been added. Which is my point.
>
> >
> > So I'm ok with either keeping this as-is (caller isn't getting
> > confused, just logging) or swallowing the return of kobject_uevent.
>
> I would just ignore the return value of kobject_uevent() along the
> lines of wakeup_sysfs_remove() below.
>
> Thanks!
>
> > > > }
> > > >
> > > > void wakeup_sysfs_remove(struct device *dev)
> > > > {
> > > > sysfs_unmerge_group(&dev->kobj, &pm_wakeup_attr_group);
> > > > + kobject_uevent(&dev->kobj, KOBJ_CHANGE);
> > > > }
> > > >
> > > > int pm_qos_sysfs_add_resume_latency(struct device *dev)
> > > > --
> > > > 2.27.0.212.ge8ba1cc988-goog
> > > >