[PATCH] leds: triggers: send uevent when changing triggers

[PATCH] leds: triggers: send uevent when changing triggers

[Colin Cross]

Some triggers create sysfs files when they are enabled.  Send a uevent
"change" notification whenever the trigger is changed to allow userspace
processes such as udev to modify permissions on the new files.

Signed-off-by: Colin Cross <ccross@android.com>
---
 drivers/leds/led-triggers.c |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
index 46b4c76..a85ce09 100644
--- a/drivers/leds/led-triggers.c
+++ b/drivers/leds/led-triggers.c
@@ -102,6 +102,12 @@ ssize_t led_trigger_show(struct device *dev, struct device_attribute *attr,
 void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trigger)
 {
 	unsigned long flags;
+	char *event = NULL;
+	char *envp[2];
+	const char *name;
+
+	name = trigger ? trigger->name : "none";
+	event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);
 
 	/* Remove any existing trigger */
 	if (led_cdev->trigger) {
@@ -122,6 +128,13 @@ void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trigger)
 		if (trigger->activate)
 			trigger->activate(led_cdev);
 	}
+
+	if (event) {
+		envp[0] = event;
+		envp[1] = NULL;
+		kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp);
+		kfree(event);
+	}
 }
 EXPORT_SYMBOL_GPL(led_trigger_set);
 
-- 
1.7.7.3

Re: [PATCH] leds: triggers: send uevent when changing triggers

[Bryan Wu]

On Wed, Jul 25, 2012 at 8:32 AM, Colin Cross <ccross@android.com> wrote:
> Some triggers create sysfs files when they are enabled.  Send a uevent
> "change" notification whenever the trigger is changed to allow userspace
> processes such as udev to modify permissions on the new files.
>

This looks like an workaround only for led trigger, can we fix this in
sysfs level?

Thanks,
-Bryan

> Signed-off-by: Colin Cross <ccross@android.com>
> ---
>  drivers/leds/led-triggers.c |   13 +++++++++++++
>  1 files changed, 13 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
> index 46b4c76..a85ce09 100644
> --- a/drivers/leds/led-triggers.c
> +++ b/drivers/leds/led-triggers.c
> @@ -102,6 +102,12 @@ ssize_t led_trigger_show(struct device *dev, struct device_attribute *attr,
>  void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trigger)
>  {
>         unsigned long flags;
> +       char *event = NULL;
> +       char *envp[2];
> +       const char *name;
> +
> +       name = trigger ? trigger->name : "none";
> +       event = kasprintf(GFP_KERNEL, "TRIGGER=%s", name);
>
>         /* Remove any existing trigger */
>         if (led_cdev->trigger) {
> @@ -122,6 +128,13 @@ void led_trigger_set(struct led_classdev *led_cdev, struct led_trigger *trigger)
>                 if (trigger->activate)
>                         trigger->activate(led_cdev);
>         }
> +
> +       if (event) {
> +               envp[0] = event;
> +               envp[1] = NULL;
> +               kobject_uevent_env(&led_cdev->dev->kobj, KOBJ_CHANGE, envp);
> +               kfree(event);
> +       }
>  }
>  EXPORT_SYMBOL_GPL(led_trigger_set);
>
> --
> 1.7.7.3
>



-- 
Bryan Wu <bryan.wu@canonical.com>
Kernel Developer    +86.186-168-78255 Mobile
Canonical Ltd.      www.canonical.com
Ubuntu - Linux for human beings | www.ubuntu.com

Re: [PATCH] leds: triggers: send uevent when changing triggers

[Greg KH]

On Wed, Jul 25, 2012 at 02:11:30PM +0800, Bryan Wu wrote:
> On Wed, Jul 25, 2012 at 8:32 AM, Colin Cross <ccross@android.com> wrote:
> > Some triggers create sysfs files when they are enabled.  Send a uevent
> > "change" notification whenever the trigger is changed to allow userspace
> > processes such as udev to modify permissions on the new files.
> >
> 
> This looks like an workaround only for led trigger, can we fix this in
> sysfs level?

How do you propose doing that?

greg k-h

Re: [PATCH] leds: triggers: send uevent when changing triggers

[Colin Cross]

On Tue, Jul 24, 2012 at 11:11 PM, Bryan Wu <bryan.wu@canonical.com> wrote:
> On Wed, Jul 25, 2012 at 8:32 AM, Colin Cross <ccross@android.com> wrote:
>> Some triggers create sysfs files when they are enabled.  Send a uevent
>> "change" notification whenever the trigger is changed to allow userspace
>> processes such as udev to modify permissions on the new files.
>>
>
> This looks like an workaround only for led trigger, can we fix this in
> sysfs level?

See the previous discussion here: https://lkml.org/lkml/2012/7/20/458

Re: [PATCH] leds: triggers: send uevent when changing triggers

[Bryan Wu]

On Thu, Jul 26, 2012 at 2:54 AM, Colin Cross <ccross@android.com> wrote:
> On Tue, Jul 24, 2012 at 11:11 PM, Bryan Wu <bryan.wu@canonical.com> wrote:
>> On Wed, Jul 25, 2012 at 8:32 AM, Colin Cross <ccross@android.com> wrote:
>>> Some triggers create sysfs files when they are enabled.  Send a uevent
>>> "change" notification whenever the trigger is changed to allow userspace
>>> processes such as udev to modify permissions on the new files.
>>>
>>
>> This looks like an workaround only for led trigger, can we fix this in
>> sysfs level?
>
> See the previous discussion here: https://lkml.org/lkml/2012/7/20/458

Thanks, I went through this thread here. Actually it was archived in
my email account, so I missed that during a trip.

Basically, I think this issue is a kind of general issue related to
sysfs, not just only for led trigger system. And adding this uevent
notification to a upper level LED driver is not good to me, if we got
similar issue in other subsystem, we should add similar fix there. Why
not we add this in sysfs when we call device_create_file(). And this
will be benefit for other drivers.

Please point out me why we can't do that in sysfs level. Thanks.
-- 
Bryan Wu <bryan.wu@canonical.com>
Kernel Developer    +86.186-168-78255 Mobile
Canonical Ltd.      www.canonical.com
Ubuntu - Linux for human beings | www.ubuntu.com

Re: [PATCH] leds: triggers: send uevent when changing triggers

[Greg KH]

On Thu, Jul 26, 2012 at 11:29:48AM +0800, Bryan Wu wrote:
> On Thu, Jul 26, 2012 at 2:54 AM, Colin Cross <ccross@android.com> wrote:
> > On Tue, Jul 24, 2012 at 11:11 PM, Bryan Wu <bryan.wu@canonical.com> wrote:
> >> On Wed, Jul 25, 2012 at 8:32 AM, Colin Cross <ccross@android.com> wrote:
> >>> Some triggers create sysfs files when they are enabled.  Send a uevent
> >>> "change" notification whenever the trigger is changed to allow userspace
> >>> processes such as udev to modify permissions on the new files.
> >>>
> >>
> >> This looks like an workaround only for led trigger, can we fix this in
> >> sysfs level?
> >
> > See the previous discussion here: https://lkml.org/lkml/2012/7/20/458
> 
> Thanks, I went through this thread here. Actually it was archived in
> my email account, so I missed that during a trip.
> 
> Basically, I think this issue is a kind of general issue related to
> sysfs, not just only for led trigger system. And adding this uevent
> notification to a upper level LED driver is not good to me, if we got
> similar issue in other subsystem, we should add similar fix there. Why
> not we add this in sysfs when we call device_create_file(). And this
> will be benefit for other drivers.
> 
> Please point out me why we can't do that in sysfs level. Thanks.

Please point out to me how you _can_ do this at a sysfs level :)

greg k-h

Re: [PATCH] leds: triggers: send uevent when changing triggers

[Bryan Wu]

On Thu, Jul 26, 2012 at 11:59 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
> On Thu, Jul 26, 2012 at 11:29:48AM +0800, Bryan Wu wrote:
>> On Thu, Jul 26, 2012 at 2:54 AM, Colin Cross <ccross@android.com> wrote:
>> > On Tue, Jul 24, 2012 at 11:11 PM, Bryan Wu <bryan.wu@canonical.com> wrote:
>> >> On Wed, Jul 25, 2012 at 8:32 AM, Colin Cross <ccross@android.com> wrote:
>> >>> Some triggers create sysfs files when they are enabled.  Send a uevent
>> >>> "change" notification whenever the trigger is changed to allow userspace
>> >>> processes such as udev to modify permissions on the new files.
>> >>>
>> >>
>> >> This looks like an workaround only for led trigger, can we fix this in
>> >> sysfs level?
>> >
>> > See the previous discussion here: https://lkml.org/lkml/2012/7/20/458
>>
>> Thanks, I went through this thread here. Actually it was archived in
>> my email account, so I missed that during a trip.
>>
>> Basically, I think this issue is a kind of general issue related to
>> sysfs, not just only for led trigger system. And adding this uevent
>> notification to a upper level LED driver is not good to me, if we got
>> similar issue in other subsystem, we should add similar fix there. Why
>> not we add this in sysfs when we call device_create_file(). And this
>> will be benefit for other drivers.
>>
>> Please point out me why we can't do that in sysfs level. Thanks.
>
> Please point out to me how you _can_ do this at a sysfs level :)
>
> greg k-h

Just one quick patch for my idea: emitting a uevent in sysfs_create_file().

--
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 00012e3..04da869 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -570,10 +570,14 @@ int sysfs_add_file(struct sysfs_dirent *dir_sd,
const struct attribute *attr,

 int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
 {
+       int err = 0;
+
        BUG_ON(!kobj || !kobj->sd || !attr);

-       return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
+       err = sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
+       kobject_uevent(kobj, KOBJ_CHANGE);

+       return err;
 }

 int sysfs_create_files(struct kobject *kobj, const struct attribute **ptr)
--


-- 
Bryan Wu <bryan.wu@canonical.com>
Kernel Developer    +86.186-168-78255 Mobile
Canonical Ltd.      www.canonical.com
Ubuntu - Linux for human beings | www.ubuntu.com

Re: [PATCH] leds: triggers: send uevent when changing triggers

[Greg KH]

On Thu, Jul 26, 2012 at 01:03:11PM +0800, Bryan Wu wrote:
> Just one quick patch for my idea: emitting a uevent in sysfs_create_file().
> 
> --
> diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
> index 00012e3..04da869 100644
> --- a/fs/sysfs/file.c
> +++ b/fs/sysfs/file.c
> @@ -570,10 +570,14 @@ int sysfs_add_file(struct sysfs_dirent *dir_sd,
> const struct attribute *attr,
> 
>  int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
>  {
> +       int err = 0;
> +
>         BUG_ON(!kobj || !kobj->sd || !attr);
> 
> -       return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
> +       err = sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
> +       kobject_uevent(kobj, KOBJ_CHANGE);

That's a veritable flood of change events when a new kobject is created,
right?  It also created uevents for a device that has not told userspace
that it is even present, which could cause massive confusion, don't you
think?

greg k-h

Re: [PATCH] leds: triggers: send uevent when changing triggers

[Bryan Wu]

On Fri, Jul 27, 2012 at 12:51 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
> On Thu, Jul 26, 2012 at 01:03:11PM +0800, Bryan Wu wrote:
>> Just one quick patch for my idea: emitting a uevent in sysfs_create_file().
>>
>> --
>> diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
>> index 00012e3..04da869 100644
>> --- a/fs/sysfs/file.c
>> +++ b/fs/sysfs/file.c
>> @@ -570,10 +570,14 @@ int sysfs_add_file(struct sysfs_dirent *dir_sd,
>> const struct attribute *attr,
>>
>>  int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
>>  {
>> +       int err = 0;
>> +
>>         BUG_ON(!kobj || !kobj->sd || !attr);
>>
>> -       return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
>> +       err = sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
>> +       kobject_uevent(kobj, KOBJ_CHANGE);
>
> That's a veritable flood of change events when a new kobject is created,
> right?  It also created uevents for a device that has not told userspace
> that it is even present, which could cause massive confusion, don't you
> think?
>

Indeed, this is unacceptable. I reworked a new patchset and just sent
our for you review.

Thanks,
-Bryan

Re: [PATCH] leds: triggers: send uevent when changing triggers

[Colin Cross]

On Thu, Jul 26, 2012 at 9:04 PM, Bryan Wu <bryan.wu@canonical.com> wrote:
> On Fri, Jul 27, 2012 at 12:51 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
>> On Thu, Jul 26, 2012 at 01:03:11PM +0800, Bryan Wu wrote:
>>> Just one quick patch for my idea: emitting a uevent in sysfs_create_file().
>>>
>>> --
>>> diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
>>> index 00012e3..04da869 100644
>>> --- a/fs/sysfs/file.c
>>> +++ b/fs/sysfs/file.c
>>> @@ -570,10 +570,14 @@ int sysfs_add_file(struct sysfs_dirent *dir_sd,
>>> const struct attribute *attr,
>>>
>>>  int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
>>>  {
>>> +       int err = 0;
>>> +
>>>         BUG_ON(!kobj || !kobj->sd || !attr);
>>>
>>> -       return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
>>> +       err = sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
>>> +       kobject_uevent(kobj, KOBJ_CHANGE);
>>
>> That's a veritable flood of change events when a new kobject is created,
>> right?  It also created uevents for a device that has not told userspace
>> that it is even present, which could cause massive confusion, don't you
>> think?
>>
>
> Indeed, this is unacceptable. I reworked a new patchset and just sent
> our for you review.
>
> Thanks,
> -Bryan

Given the rejection of the other solutions to this problem, and chance
of getting this acked?

Re: [PATCH] leds: triggers: send uevent when changing triggers

[Bryan Wu]

On Wed, Aug 1, 2012 at 2:28 AM, Colin Cross <ccross@android.com> wrote:
> On Thu, Jul 26, 2012 at 9:04 PM, Bryan Wu <bryan.wu@canonical.com> wrote:
>> On Fri, Jul 27, 2012 at 12:51 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
>>> On Thu, Jul 26, 2012 at 01:03:11PM +0800, Bryan Wu wrote:
>>>> Just one quick patch for my idea: emitting a uevent in sysfs_create_file().
>>>>
>>>> --
>>>> diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
>>>> index 00012e3..04da869 100644
>>>> --- a/fs/sysfs/file.c
>>>> +++ b/fs/sysfs/file.c
>>>> @@ -570,10 +570,14 @@ int sysfs_add_file(struct sysfs_dirent *dir_sd,
>>>> const struct attribute *attr,
>>>>
>>>>  int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
>>>>  {
>>>> +       int err = 0;
>>>> +
>>>>         BUG_ON(!kobj || !kobj->sd || !attr);
>>>>
>>>> -       return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
>>>> +       err = sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
>>>> +       kobject_uevent(kobj, KOBJ_CHANGE);
>>>
>>> That's a veritable flood of change events when a new kobject is created,
>>> right?  It also created uevents for a device that has not told userspace
>>> that it is even present, which could cause massive confusion, don't you
>>> think?
>>>
>>
>> Indeed, this is unacceptable. I reworked a new patchset and just sent
>> our for you review.
>>
>> Thanks,
>> -Bryan
>
> Given the rejection of the other solutions to this problem, and chance
> of getting this acked?

Greg, Richard and Henrique, can I take you guys' Ack here?

Thanks,
-- 
Bryan Wu <bryan.wu@canonical.com>
Kernel Developer    +86.186-168-78255 Mobile
Canonical Ltd.      www.canonical.com
Ubuntu - Linux for human beings | www.ubuntu.com

Re: [PATCH] leds: triggers: send uevent when changing triggers

[Greg KH]

On Tue, Aug 07, 2012 at 10:57:29AM +0800, Bryan Wu wrote:
> On Wed, Aug 1, 2012 at 2:28 AM, Colin Cross <ccross@android.com> wrote:
> > On Thu, Jul 26, 2012 at 9:04 PM, Bryan Wu <bryan.wu@canonical.com> wrote:
> >> On Fri, Jul 27, 2012 at 12:51 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
> >>> On Thu, Jul 26, 2012 at 01:03:11PM +0800, Bryan Wu wrote:
> >>>> Just one quick patch for my idea: emitting a uevent in sysfs_create_file().
> >>>>
> >>>> --
> >>>> diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
> >>>> index 00012e3..04da869 100644
> >>>> --- a/fs/sysfs/file.c
> >>>> +++ b/fs/sysfs/file.c
> >>>> @@ -570,10 +570,14 @@ int sysfs_add_file(struct sysfs_dirent *dir_sd,
> >>>> const struct attribute *attr,
> >>>>
> >>>>  int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
> >>>>  {
> >>>> +       int err = 0;
> >>>> +
> >>>>         BUG_ON(!kobj || !kobj->sd || !attr);
> >>>>
> >>>> -       return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
> >>>> +       err = sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
> >>>> +       kobject_uevent(kobj, KOBJ_CHANGE);
> >>>
> >>> That's a veritable flood of change events when a new kobject is created,
> >>> right?  It also created uevents for a device that has not told userspace
> >>> that it is even present, which could cause massive confusion, don't you
> >>> think?
> >>>
> >>
> >> Indeed, this is unacceptable. I reworked a new patchset and just sent
> >> our for you review.
> >>
> >> Thanks,
> >> -Bryan
> >
> > Given the rejection of the other solutions to this problem, and chance
> > of getting this acked?
> 
> Greg, Richard and Henrique, can I take you guys' Ack here?

Ack for what specific patch are you referring to?

greg k-h

Re: [PATCH] leds: triggers: send uevent when changing triggers

[Greg KH]

On Tue, Aug 07, 2012 at 11:38:10AM +0800, Bryan Wu wrote:
> 
> 在 2012-8-7 上午11:34，"Greg KH" <gregkh@linuxfoundation.org>写道：
> >
> > On Tue, Aug 07, 2012 at 10:57:29AM +0800, Bryan Wu wrote:
> > > On Wed, Aug 1, 2012 at 2:28 AM, Colin Cross <ccross@android.com> wrote:
> > > > On Thu, Jul 26, 2012 at 9:04 PM, Bryan Wu <bryan.wu@canonical.com> wrote:
> > > >> On Fri, Jul 27, 2012 at 12:51 AM, Greg KH <gregkh@linuxfoundation.org>
> wrote:
> > > >>> On Thu, Jul 26, 2012 at 01:03:11PM +0800, Bryan Wu wrote:
> > > >>>> Just one quick patch for my idea: emitting a uevent in
> sysfs_create_file().
> > > >>>>
> > > >>>> --
> > > >>>> diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
> > > >>>> index 00012e3..04da869 100644
> > > >>>> --- a/fs/sysfs/file.c
> > > >>>> +++ b/fs/sysfs/file.c
> > > >>>> @@ -570,10 +570,14 @@ int sysfs_add_file(struct sysfs_dirent *dir_sd,
> > > >>>> const struct attribute *attr,
> > > >>>>
> > > >>>>  int sysfs_create_file(struct kobject * kobj, const struct attribute *
> attr)
> > > >>>>  {
> > > >>>> +       int err = 0;
> > > >>>> +
> > > >>>>         BUG_ON(!kobj || !kobj->sd || !attr);
> > > >>>>
> > > >>>> -       return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
> > > >>>> +       err = sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
> > > >>>> +       kobject_uevent(kobj, KOBJ_CHANGE);
> > > >>>
> > > >>> That's a veritable flood of change events when a new kobject is
> created,
> > > >>> right?  It also created uevents for a device that has not told
> userspace
> > > >>> that it is even present, which could cause massive confusion, don't you
> > > >>> think?
> > > >>>
> > > >>
> > > >> Indeed, this is unacceptable. I reworked a new patchset and just sent
> > > >> our for you review.
> > > >>
> > > >> Thanks,
> > > >> -Bryan
> > > >
> > > > Given the rejection of the other solutions to this problem, and chance
> > > > of getting this acked?
> > >
> > > Greg, Richard and Henrique, can I take you guys' Ack here?
> >
> > Ack for what specific patch are you referring to?
> >
> 
> For Colin's patch in the first email of this loop.

I have no idea what that patch contained anymore, that was 1000+ emails
ago...

Re: [PATCH] leds: triggers: send uevent when changing triggers

[Henrique de Moraes Holschuh]

On Tue, 07 Aug 2012, Bryan Wu wrote:
> On Wed, Aug 1, 2012 at 2:28 AM, Colin Cross <ccross@android.com> wrote:
> > On Thu, Jul 26, 2012 at 9:04 PM, Bryan Wu <bryan.wu@canonical.com> wrote:
> >> On Fri, Jul 27, 2012 at 12:51 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
> >>> On Thu, Jul 26, 2012 at 01:03:11PM +0800, Bryan Wu wrote:
> >>>> Just one quick patch for my idea: emitting a uevent in sysfs_create_file().
> >>>>
> >>>> --
> >>>> diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
> >>>> index 00012e3..04da869 100644
> >>>> --- a/fs/sysfs/file.c
> >>>> +++ b/fs/sysfs/file.c
> >>>> @@ -570,10 +570,14 @@ int sysfs_add_file(struct sysfs_dirent *dir_sd,
> >>>> const struct attribute *attr,
> >>>>
> >>>>  int sysfs_create_file(struct kobject * kobj, const struct attribute * attr)
> >>>>  {
> >>>> +       int err = 0;
> >>>> +
> >>>>         BUG_ON(!kobj || !kobj->sd || !attr);
> >>>>
> >>>> -       return sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
> >>>> +       err = sysfs_add_file(kobj->sd, attr, SYSFS_KOBJ_ATTR);
> >>>> +       kobject_uevent(kobj, KOBJ_CHANGE);
> >>>
> >>> That's a veritable flood of change events when a new kobject is created,
> >>> right?  It also created uevents for a device that has not told userspace
> >>> that it is even present, which could cause massive confusion, don't you
> >>> think?
> >>>
> >>
> >> Indeed, this is unacceptable. I reworked a new patchset and just sent
> >> our for you review.
> >>
> >> Thanks,
> >> -Bryan
> >
> > Given the rejection of the other solutions to this problem, and chance
> > of getting this acked?
> 
> Greg, Richard and Henrique, can I take you guys' Ack here?

Yes, you have my Acked-by, provided that the uevent is NOT sent before
the led is fully registered (I cannot check right now if the patch does
this right or not.  I apologise in advance if this was an unecessary
question).

I don't care whether the uevent gets sent right after registration, or
only when the trigger *changes* after registering.  But someone might,
so it would be nice to document this.

Considering Greg's answer, maybe it would be best to resend the patch
with the point above clarified in the commit message or in the in-tree
documentation of the LED class?

-- 
  "One disk to rule them all, One disk to find them. One disk to bring
  them all and in the darkness grind them. In the Land of Redmond
  where the shadows lie." -- The Silicon Valley Tarot
  Henrique Holschuh

Re: [PATCH] leds: triggers: send uevent when changing triggers

[Colin Cross]

On Tue, Aug 7, 2012 at 7:36 AM, Henrique de Moraes Holschuh
<hmh@hmh.eng.br> wrote:
> On Tue, 07 Aug 2012, Bryan Wu wrote:
<snip>

>> Greg, Richard and Henrique, can I take you guys' Ack here?
>
> Yes, you have my Acked-by, provided that the uevent is NOT sent before
> the led is fully registered (I cannot check right now if the patch does
> this right or not.  I apologise in advance if this was an unecessary
> question).
>
> I don't care whether the uevent gets sent right after registration, or
> only when the trigger *changes* after registering.  But someone might,
> so it would be nice to document this.
>
> Considering Greg's answer, maybe it would be best to resend the patch
> with the point above clarified in the commit message or in the in-tree
> documentation of the LED class?

led_trigger_set_default is called last from led_classdev_register, so
it will send a uevent during registration but after it is fully
registered.  I will resend the patch with the clarification.