Thread (7 messages) 7 messages, 2 authors, 2020-07-07

Re: [PATCH v4 1/1] power: Emit changed uevent on wakeup_sysfs_add/remove

From: "Rafael J. Wysocki" <rafael@kernel.org>
Date: 2020-07-07 16:28:20
Also in: linux-pm, lkml

On Tue, Jul 7, 2020 at 6:24 PM Abhishek Pandit-Subedi
[off-list ref] wrote:
quoted hunk ↗ jump to hunk
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 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.
 }

 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
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