[PATCH v5 0/1] power: Emit change uevent when updating sysfs

[PATCH v5 0/1] power: Emit change uevent when updating sysfs

[Abhishek Pandit-Subedi]

Hi linux-pm,

ChromeOS has a udev rule to chown the `power/wakeup` attribute so that
the power manager can modify it during runtime.

(https://source.chromium.org/chromiumos/chromiumos/codesearch/+/master:src/platform2/power_manager/udev/99-powerd-permissions.rules)

In our automated tests, we found that the `power/wakeup` attributes
weren't being chown-ed for some boards. On investigating, I found that
when the drivers probe and call device_set_wakeup_capable, no uevent was
being emitted for the newly added power/wakeup attribute. This was
manifesting at boot on some boards (Marvell SDIO bluetooth and Broadcom
Serial bluetooth drivers) or during usb disconnects during resume
(Realtek btusb driver with reset resume quirk).

It seems reasonable to me that changes to the attributes of a device
should cause a changed uevent so I have added that here.

Here's an example of the kernel events after toggling the authorized
bit of /sys/bus/usb/devices/1-3/

$ echo 0 > /sys/bus/usb/devices/1-3/authorized
KERNEL[27.357994] remove   /devices/pci0000:00/0000:00:15.0/usb1/1-3/1-3:1.0/bluetooth/hci0/rfkill1 (rfkill)
KERNEL[27.358049] remove   /devices/pci0000:00/0000:00:15.0/usb1/1-3/1-3:1.0/bluetooth/hci0 (bluetooth)
KERNEL[27.358458] remove   /devices/pci0000:00/0000:00:15.0/usb1/1-3/1-3:1.0 (usb)
KERNEL[27.358486] remove   /devices/pci0000:00/0000:00:15.0/usb1/1-3/1-3:1.1 (usb)
KERNEL[27.358529] change   /devices/pci0000:00/0000:00:15.0/usb1/1-3 (usb)

$ echo 1 > /sys/bus/usb/devices/1-3/authorized
KERNEL[36.415749] change   /devices/pci0000:00/0000:00:15.0/usb1/1-3 (usb)
KERNEL[36.415798] add      /devices/pci0000:00/0000:00:15.0/usb1/1-3/1-3:1.0 (usb)
KERNEL[36.417414] add      /devices/pci0000:00/0000:00:15.0/usb1/1-3/1-3:1.0/bluetooth/hci0 (bluetooth)
KERNEL[36.417447] add      /devices/pci0000:00/0000:00:15.0/usb1/1-3/1-3:1.0/bluetooth/hci0/rfkill2 (rfkill)
KERNEL[36.417481] add      /devices/pci0000:00/0000:00:15.0/usb1/1-3/1-3:1.1 (usb)

Series-version 4 update:
Tested again on device and verified it's working as expected:
KERNEL[52.678174] remove   /devices/pci0000:00/0000:00:15.0/usb1/1-3/1-3:1.0/bluetooth/hci0/rfkill2 (rfkill)
KERNEL[52.678211] remove   /devices/pci0000:00/0000:00:15.0/usb1/1-3/1-3:1.0/bluetooth/hci0 (bluetooth)
KERNEL[52.678251] remove   /devices/pci0000:00/0000:00:15.0/usb1/1-3/1-3:1.0 (usb)
KERNEL[52.679721] remove   /devices/pci0000:00/0000:00:15.0/usb1/1-3/1-3:1.1 (usb)
KERNEL[52.679772] change   /devices/pci0000:00/0000:00:15.0/usb1/1-3 (usb)
KERNEL[56.022259] change   /devices/pci0000:00/0000:00:15.0/usb1/1-3 (usb)
KERNEL[56.022306] add      /devices/pci0000:00/0000:00:15.0/usb1/1-3/1-3:1.0 (usb)
KERNEL[56.022488] add      /devices/pci0000:00/0000:00:15.0/usb1/1-3/1-3:1.0/bluetooth/hci0 (bluetooth)
KERNEL[56.022531] add      /devices/pci0000:00/0000:00:15.0/usb1/1-3/1-3:1.0/bluetooth/hci0/rfkill3 (rfkill)
KERNEL[56.023392] add      /devices/pci0000:00/0000:00:15.0/usb1/1-3/1-3:1.1 (usb)

Thanks
Abhishek

Changes in v5:
- Ignore return from kobject_uevent when adding to sysfs

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

Abhishek Pandit-Subedi (1):
  power: Emit changed uevent on wakeup_sysfs_add/remove

 drivers/base/power/sysfs.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

-- 
2.27.0.212.ge8ba1cc988-goog

[PATCH v5 1/1] power: Emit changed uevent on wakeup_sysfs_add/remove

[Abhishek Pandit-Subedi]

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 <abhishekpandit@chromium.org>
---

Changes in v5:
- Ignore return from kobject_uevent when adding to sysfs

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..c7b24812523c9e 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)
+		kobject_uevent(&dev->kobj, KOBJ_CHANGE);
+
+	return ret;
 }
 
 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

Re: [PATCH v5 1/1] power: Emit changed uevent on wakeup_sysfs_add/remove

[Greg Kroah-Hartman]

On Tue, Jul 07, 2020 at 10:28:44AM -0700, Abhishek Pandit-Subedi 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 <abhishekpandit@chromium.org>

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Re: [PATCH v5 1/1] power: Emit changed uevent on wakeup_sysfs_add/remove

[Greg Kroah-Hartman]

On Tue, Jul 07, 2020 at 10:28:44AM -0700, Abhishek Pandit-Subedi 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 <abhishekpandit@chromium.org>

Rafael, any objection to this?  Do you want me to take it through my
tree, or are you going to take it through yours?  Either is fine for me.

thanks,

greg k-h

Re: [PATCH v5 1/1] power: Emit changed uevent on wakeup_sysfs_add/remove

[Rafael J. Wysocki]

On Thu, Jul 23, 2020 at 8:32 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Tue, Jul 07, 2020 at 10:28:44AM -0700, Abhishek Pandit-Subedi 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 <abhishekpandit@chromium.org>
>
> Rafael, any objection to this?  Do you want me to take it through my
> tree, or are you going to take it through yours?  Either is fine for me.

It's already there in my tree with the R-by tag from you.

Cheers!

Re: [PATCH v5 1/1] power: Emit changed uevent on wakeup_sysfs_add/remove

[Greg Kroah-Hartman]

On Mon, Jul 27, 2020 at 03:38:02PM +0200, Rafael J. Wysocki wrote:
> On Thu, Jul 23, 2020 at 8:32 PM Greg Kroah-Hartman
> <gregkh@linuxfoundation.org> wrote:
> >
> > On Tue, Jul 07, 2020 at 10:28:44AM -0700, Abhishek Pandit-Subedi 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 <abhishekpandit@chromium.org>
> >
> > Rafael, any objection to this?  Do you want me to take it through my
> > tree, or are you going to take it through yours?  Either is fine for me.
> 
> It's already there in my tree with the R-by tag from you.

{sigh}  Sorry for the noise.

greg k-h