On Tue, Sep 03, 2019 at 08:18:36PM +0200, Jacek Anaszewski wrote: > On 9/3/19 4:21 PM, Akinobu Mita wrote: > > 2019年9月3日(火) 23:07 Greg KH <gre...@linuxfoundation.org>: > >> > >> On Tue, Sep 03, 2019 at 10:55:40PM +0900, Akinobu Mita wrote: > >>> 2019年9月3日(火) 4:08 Greg KH <gre...@linuxfoundation.org>: > >>>> > >>>> On Mon, Sep 02, 2019 at 08:47:02PM +0200, Jacek Anaszewski wrote: > >>>>> On 9/2/19 8:12 PM, Greg KH wrote: > >>>>>> On Sun, Sep 01, 2019 at 06:53:34PM +0200, Jacek Anaszewski wrote: > >>>>>>> Hi Akinobu, > >>>>>>> > >>>>>>> Thank you for the patch. > >>>>>>> > >>>>>>> I have one nit below but in general it looks good to me. > >>>>>>> I've tested it with 2000 mtd triggers (~14kB file size) > >>>>>>> and it worked flawlessly. > >>>>>>> > >>>>>>> Still, I would like to have ack from Greg for it. > >>>>>>> > >>>>>>> Adding Greg on Cc. > >>>>>>> > >>>>>>> On 8/29/19 4:49 PM, Akinobu Mita wrote: > >>>>>>>> Reading /sys/class/leds/<led>/trigger returns all available LED > >>>>>>>> triggers. > >>>>>>>> However, the size of this file is limited to PAGE_SIZE because of the > >>>>>>>> limitation for sysfs attribute. > >>>>>>>> > >>>>>>>> Enabling LED CPU trigger on systems with thousands of CPUs easily > >>>>>>>> hits > >>>>>>>> PAGE_SIZE limit, and makes it impossible to see all available LED > >>>>>>>> triggers > >>>>>>>> and which trigger is currently activated. > >>>>>>>> > >>>>>>>> This converts /sys/class/leds/<led>/trigger to bin attribute and > >>>>>>>> removes > >>>>>>>> the PAGE_SIZE limitation. > >>>>>> > >>>>>> But this is NOT a binary file. A sysfs binary file is used for when > >>>>>> the > >>>>>> kernel passes data to or from hardware without any parsing of the data > >>>>>> by the kernel. > >>>>>> > >>>>>> You are not doing that here, you are abusing the "one value per file" > >>>>>> rule of sysfs so much that you are forced to work around the limitation > >>>>>> it put in place on purpose to keep you from doing stuff like this. > >>>>>> > >>>>>> Please fix this "correctly" by creating a new api that works properly > >>>>>> and just live with the fact that this file will never work correctly > >>>>>> and > >>>>>> move everyone to use the new api instead. > >>>>>> > >>>>>> Don't keep on abusing the interface by workarounds like this, it is not > >>>>>> ok. > >>>>> > >>>>> In the message [0] you pledged to give us exception for that, provided > >>>>> it will be properly documented in the code. I suppose you now object > >>>>> because the patch does not meet that condition. > >>>> > >>>> Well, I honestly don't remember writing that email, but it was 5 months > >>>> and many thousands of emails ago :) > >>>> > >>>> Also, you all didn't document the heck out of this. So no, I really do > >>>> not want to see this patch accepted as-is. > >>>> > >>>>> Provided that will be fixed, can we count on your ack for the > >>>>> implementation of the solution you proposed? :-) > >>>> > >>>> Let's see the patch that actually implements what I suggested first :) > >>> > >>> I'd propose introducing a new procfs file (/proc/led-triggers) and new > >>> /sys/class/leds/<led>/current-trigger api. > >>> > >>> Reading /proc/led-triggers file shows all available triggers. > >>> This violates "one value per file", but it's a procfs file. > >> > >> No, procfs files are ONLY for process-related things. Don't keep the > >> insanity of this file format by just moving it out of sysfs and into > >> procfs :) > > > > I see. > > > > How about creating one file or directory for each led-trigger in > > /sys/kernel/led-triggers directory? > > > > e.g. > > > > $ ls /sys/kernel/led-triggers > > audio-micmute ide-disk phy0assoc > > audio-mute kbd-altgrlock phy0radio > > ... > > hidpp_battery_3-full panic > I think that /sys/class/leds/triggers would better reflect the reality. > After all LED Trigger core belongs to LED subsystem.
Yes, sorry, I missed that "kernel" directory, that's a non-starter, use the class directory as that is what it is for here. greg k-h
