linux-kernel - Re: [PATCH RFC 2/6 v3] gpio: Add sysfs support to block GPIO API

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:	Mon, 15 Oct 2012 23:38:48 +0200
From:	Roland Stigge <stigge@...com.de>
To:	Linus Walleij <linus.walleij@...aro.org>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Grant Likely <grant.likely@...retlab.ca>,
	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>,
	Daniel Glöckner 
	<daniel-gl@....net>, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, w.sang@...gutronix.de,
	jbe@...gutronix.de, highguy@...il.com,
	broonie@...nsource.wolfsonmicro.com
Subject: Re: [PATCH RFC 2/6 v3] gpio: Add sysfs support to block GPIO API

On 15/10/12 22:30, Linus Walleij wrote:
> I don't like it either, basically because the GPIO sysfs is not
> entirely sound.
> 
> Another patch that is circulating concerns edge triggers and similar,
> and it appear that some parts of the GPIO sysfs is for example
> redefining and exporting IRQchip properties like trigger edge
> in sysfs, while the settings of the irqchip actually used by the driver
> is not reflected in the other direction. So you can *set* these things
> by writing in the GPIO sysfs, but never trust what you *read* from
> there. And you can set what edges an IRQ will trigger on a certain
> GPIO, and the way to handle the IRQs from usespace is to poll
> on a value. This is not really documented but well ...

I'm not convinced this generally also applies to the block GPIO patches.
Or that it can't be fixed.

> The reason an ioctl() IMO is better suited to do the job is that
> it can properly represent a multiple-value operation on several
> GPIOs at the same time in a struct, and it can conversely inform
> userspace about which GPIOs may be a block of signals that
> can be fired simultaneously instead of going to string parsing
> and binary values in sysfs which look like worse hacks to me.

There is no binary values in the sysfs for the block GPIO patches, and
regarding string parsing - yes, that's sysfs. :-)

Roland
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/