linux-kernel - Re: [PATCH RFC V3.5] leds: trigger: Introduce an USB port trigger

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 26 Aug 2016 17:58:23 +0200
From:   Rafał Miłecki <zajec5@...il.com>
To:     Jacek Anaszewski <jacek.anaszewski@...il.com>
Cc:     Alan Stern <stern@...land.harvard.edu>,
        Jacek Anaszewski <j.anaszewski@...sung.com>,
        Richard Purdie <rpurdie@...ys.net>,
        Felipe Balbi <balbi@...nel.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Peter Chen <hzpeterchen@...il.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        Rafał Miłecki <rafal@...ecki.pl>,
        Jonathan Corbet <corbet@....net>,
        Ezequiel Garcia <ezequiel@...guardiasur.com.ar>,
        Stephan Linz <linz@...pro.net>,
        Matthias Brugger <mbrugger@...e.com>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:LED SUBSYSTEM" <linux-leds@...r.kernel.org>,
        Pavel Machek <pavel@....cz>
Subject: Re: [PATCH RFC V3.5] leds: trigger: Introduce an USB port trigger

On 25 August 2016 at 20:48, Jacek Anaszewski <jacek.anaszewski@...il.com> wrote:
> On 08/25/2016 04:30 PM, Alan Stern wrote:
>>
>> On Thu, 25 Aug 2016, Jacek Anaszewski wrote:
>>
>>> I'd see it as follows:
>>>
>>> #cat available_ports
>>> #1-1 1-2 2-1
>>>
>>> #echo "1-1" > new_port
>>>
>>> #cat observed_ports
>>> #1-1
>>>
>>> #echo "2-1" > new_port
>>>
>>> #cat observed_ports
>>> #1-1 2-1
>>>
>>> We've already had few discussions about the sysfs designs trying
>>> to break the one-value-per-file rule for LED class device, and
>>> there was always strong resistance against.
>>
>>
>> This scheme has multiple values in both the available_ports and
>> observed_ports files.  :-(  Not that I have any better suggestions...
>
>
> Right, I forgot to add a note here, that this follows space
> separated list pattern similarly as in case of triggers attribute.
> Of course other suggestions are welcome.

So ppl have doubts about multiple values in a single sysfs file
(whatever we call it: "ports" or "observed_ports"). Greg clearly said:
> sysfs is "one value per file", here you are listing a bunch of things in
> one sysfs file.  Please don't do that.

What about my idea of using "ports" subdirectory and having each port
as separated file inside that subdir? I think there are two ways of
doing this:

1) Having "ports" subdir with 0x0000 chmod files, one per each port
specified as observable
In this solution we need "new_port" and "remove_port" that can be used
for management of observable ports.
I think Jacek wasn't happy with this chmod and he believes Greg meant R/W files.

2) Having "ports" subdir with RW files, one per each existing physical port
In this situation we don't need "new_port" or "remove_port". If we
want port to be observable we just do:
echo 1 > 1-1
Implementing this solution needs reading more details from USB subsystem.

Do you find any of solutions with "ports" subdir better than dealing
with new-line/space separated values in a single sysfs file?

-- 
Rafał