On Fri, Jul 20, 2012 at 10:14:27PM -0700, Colin Cross wrote: > On Fri, Jul 20, 2012 at 9:08 PM, Greg KH <gre...@linuxfoundation.org> wrote: > > On Fri, Jul 20, 2012 at 05:46:14PM -0700, Colin Cross wrote: > >> I'm trying to use the standard ledtrig-timer.c code to handle led > >> blinking for notifications on an Android device, and I'm hitting some > >> issues with setting permissions on the dynamically created delay_on > >> and delay_off attributes. For most sysfs files, we have userspace > >> uevent parser that watches for device add notifications and > >> chowns/chmods attributes. This doesn't work for delay_on and > >> delay_off, because they are created later, when "timer" is written to > >> the trigger attribute. There is no uevent when the new files are > >> created, and sysfs doesn't support inotify, so I don't see any way to > >> receive an event to set the permissions. This issue exists any time > >> that device_create_file is called after device_add. > >> > >> What is the appropriate way to get an event to set the permissions? > >> Add inotify support for sysfs file creation? Send a KOBJ_CHANGE > >> uevent in device_create_file? > > > > No. > > > >> Send a KOBJ_CHANGE uevent from the driver after calling > >> device_create_file? > > > > Yes. > > > >> Dynamically create a timer device under /sys/class/leds/<led> so a new > >> add uevent gets sent? > > > > Ick. > > > >> Promote blinking to be a core led feature instead of a trigger, so the > >> files are always present? > > > > That's the best thing, why not just do that? > > It doesn't solve the general case. For example, any driver that is > loaded as a module and then calls device_create_file will suffer the > same problem.
That's very true, and is why they shouldn't be doing that :) thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
