Re: [PATCH net-next v3 6/9] drivers/base/power: add dpm_sysfs_change_owner()

On Thu, Feb 20, 2020 at 11:21 AM Christian Brauner
[off-list ref] wrote:

On Thu, Feb 20, 2020 at 11:02:04AM +0100, Rafael J. Wysocki wrote:

quoted

On Tue, Feb 18, 2020 at 5:30 PM Christian Brauner
[off-list ref] wrote:

quoted

Add a helper to change the owner of a device's power entries. This
needs to happen when the ownership of a device is changed, e.g. when
moving network devices between network namespaces.
This function will be used to correctly account for ownership changes,
e.g. when moving network devices between network namespaces.

Signed-off-by: Christian Brauner <redacted>
---
/* v2 */
- "Rafael J. Wysocki" [off-list ref]:
  -  Fold if (dev->power.wakeup && dev->power.wakeup->dev) check into
     if (device_can_wakeup(dev)) check since the former can never be true if
     the latter is false.

- Christian Brauner [off-list ref]:
  - Place (dev->power.wakeup && dev->power.wakeup->dev) check under
    CONFIG_PM_SLEEP ifdefine since it will wakeup_source will only be available
    when this config option is set.

/* v3 */
-  Greg Kroah-Hartman [off-list ref]:
   - Add explicit uid/gid parameters.
---
 drivers/base/core.c        |  4 ++++
 drivers/base/power/power.h |  3 +++
 drivers/base/power/sysfs.c | 42 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 49 insertions(+)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index ec0d5e8cfd0f..efec2792f5d7 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c

@@ -3522,6 +3522,10 @@ int device_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
        if (error)
                goto out;

+       error = dpm_sysfs_change_owner(dev, kuid, kgid);
+       if (error)
+               goto out;
+
 #ifdef CONFIG_BLOCK
        if (sysfs_deprecated && dev->class == &block_class)
                goto out;

diff --git a/drivers/base/power/power.h b/drivers/base/power/power.h
index 444f5c169a0b..54292cdd7808 100644
--- a/drivers/base/power/power.h
+++ b/drivers/base/power/power.h

@@ -74,6 +74,7 @@ extern int pm_qos_sysfs_add_flags(struct device *dev);
 extern void pm_qos_sysfs_remove_flags(struct device *dev);
 extern int pm_qos_sysfs_add_latency_tolerance(struct device *dev);
 extern void pm_qos_sysfs_remove_latency_tolerance(struct device *dev);
+extern int dpm_sysfs_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid);

 #else /* CONFIG_PM */

@@ -88,6 +89,8 @@ static inline void pm_runtime_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 int dpm_sysfs_change_owner(struct device *dev, kuid_t kuid,
+                                        kgid_t kgid) { return 0; }

 #endif

diff --git a/drivers/base/power/sysfs.c b/drivers/base/power/sysfs.c
index d7d82db2e4bc..4e79afcd5ca8 100644
--- a/drivers/base/power/sysfs.c
+++ b/drivers/base/power/sysfs.c

@@ -684,6 +684,48 @@ int dpm_sysfs_add(struct device *dev)
        return rc;
 }

+int dpm_sysfs_change_owner(struct device *dev, kuid_t kuid, kgid_t kgid)
+{
+       int rc;
+
+       if (device_pm_not_required(dev))
+               return 0;
+
+       rc = sysfs_group_change_owner(&dev->kobj, &pm_attr_group, kuid, kgid);
+       if (rc)
+               return rc;
+
+       if (pm_runtime_callbacks_present(dev)) {
+               rc = sysfs_group_change_owner(
+                       &dev->kobj, &pm_runtime_attr_group, kuid, kgid);
+               if (rc)
+                       return rc;
+       }
+       if (device_can_wakeup(dev)) {
+               rc = sysfs_group_change_owner(&dev->kobj, &pm_wakeup_attr_group,
+                                             kuid, kgid);
+               if (rc)
+                       return rc;
+
+#ifdef CONFIG_PM_SLEEP
+               if (dev->power.wakeup && dev->power.wakeup->dev) {
+                       rc = device_change_owner(dev->power.wakeup->dev, kuid,
+                                                kgid);
+                       if (rc)
+                               return rc;
+               }
+#endif

First off, I don't particularly like #ifdefs in function bodies.  In
particular, there is a CONFIG_PM_SLEEP block in this file already and
you could define a new function in there to carry out the above
operations, and provide an empty stub of it for the "unset" case.
Failing to do so is somewhat on the "rushing things in" side in my
view.

How ifdefines are used is highly dependent on the subsystem; networking
ofen uses in-place ifdefines in some parts and not in others. That has
nothing to do with rushing things. I'm happy to change it to your
preferences.

Thanks!

Thanks for pointing out your expectations. But please don't
assume bad intentions on my part because I'm not meeting them right
away. It often is the case that adding a helper that is called in one
place is not well-received.

Fair enough, sorry for being harsh.