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

[Greg KH <gregkh@linuxfoundation.org>]

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