From: Greg KH <gregkh@linuxfoundation.org>
To: Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>,
linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org,
Pavel Machek <pavel@ucw.cz>, Dan Murphy <dmurphy@ti.com>
Subject: Re: [PATCH] leds: remove PAGE_SIZE limit of /sys/class/leds/<led>/trigger
Date: Mon, 2 Sep 2019 21:08:43 +0200 [thread overview]
Message-ID: <20190902190843.GB25019@kroah.com> (raw)
In-Reply-To: <1cd468a3-b6e5-a93b-739a-f30288318356@gmail.com>
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 :)
thanks,
greg k-h
next prev parent reply other threads:[~2019-09-02 19:08 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-29 14:49 [PATCH] leds: remove PAGE_SIZE limit of /sys/class/leds/<led>/trigger Akinobu Mita
2019-09-01 16:53 ` Jacek Anaszewski
2019-09-02 18:12 ` Greg KH
2019-09-02 18:47 ` Jacek Anaszewski
2019-09-02 19:08 ` Greg KH [this message]
2019-09-03 13:55 ` Akinobu Mita
2019-09-03 14:07 ` Greg KH
2019-09-03 14:21 ` Akinobu Mita
2019-09-03 14:44 ` Greg KH
2019-09-03 18:18 ` Jacek Anaszewski
2019-09-03 18:32 ` Greg KH
2019-09-03 20:30 ` Pavel Machek
2019-09-01 17:23 ` Pavel Machek
2019-09-12 14:39 [PATCH] leds: fix /sys/class/leds/<led>/trigger Akinobu Mita
2019-09-12 14:39 ` [PATCH] leds: remove PAGE_SIZE limit of /sys/class/leds/<led>/trigger Akinobu Mita
2019-09-12 17:15 ` Jacek Anaszewski
2019-09-13 0:34 ` Akinobu Mita
2019-09-13 5:00 ` Greg Kroah-Hartman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190902190843.GB25019@kroah.com \
--to=gregkh@linuxfoundation.org \
--cc=akinobu.mita@gmail.com \
--cc=dmurphy@ti.com \
--cc=jacek.anaszewski@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-leds@vger.kernel.org \
--cc=pavel@ucw.cz \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).