linux-kernel - Re: [PATCH] Introduce {sysfs,device}_create_file

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]

Message-ID: <20100512193912.GA17500@oksana.dev.rtsoft.ru>
Date:	Wed, 12 May 2010 23:39:12 +0400
From:	Anton Vorontsov <cbouatmailru@...il.com>
To:	Greg KH <gregkh@...e.de>
Cc:	Kay Sievers <kay.sievers@...y.org>, Daniel Mack <daniel@...aq.de>,
	linux-kernel@...r.kernel.org,
	David Woodhouse <dwmw2@...radead.org>,
	Alexey Starikovskiy <astarikovskiy@...e.de>,
	Len Brown <len.brown@...el.com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Matt Reimer <mreimer@...p.net>,
	Evgeniy Polyakov <zbr@...emap.net>, Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH] Introduce {sysfs,device}_create_file_mode

On Wed, May 12, 2010 at 12:19:55PM -0700, Greg KH wrote:
> On Wed, May 12, 2010 at 09:12:46PM +0200, Kay Sievers wrote:
> > On Wed, May 12, 2010 at 21:08, Anton Vorontsov <cbouatmailru@...il.com> wrote:
> > > On Wed, May 12, 2010 at 11:38:06AM -0700, Greg KH wrote:
> > >> On Wed, May 12, 2010 at 10:15:46PM +0400, Anton Vorontsov wrote:
> > >> > We need to create attributes with different modes across devices.
> > >> > We can do this by modifying attr.mode between device_create_file
> > >> > invocations, but that is racy in case of globally defined attrs.
> > >> >
> > >> > Luckily, there's sysfs_add_file_mode() function that seems to do
> > >> > exactly what we want, and if we use it, we don't need any locks
> > >> > to avoid races. Though, it isn't exposed via device-drivers core
> > >> > API.
> > >>
> > >> But you race the creation of the device notifying userspace, and then
> > >> the file being created, right?
> > >
> > > Yep, you've raised that question once, like 3 years ago. :-)
> > >
> > > http://lkml.org/lkml/2007/4/11/452
> > > http://lkml.org/lkml/2007/4/12/144
> > >
> > > In short: we can't use attr groups since the attributes creation
> > > is conditional. And we especially don't want to use the attr groups
> > > for attrs with different modes. But it's not a problem, because...
> > 
> > Groups have a filter callback for every member, to decide if the
> > attribute should be created or not.
> 
> Yeah, that's how we solved that issue a long time ago :)

But not loud enough for us to notice. ;-)

> Can you please switch to using attribute groups now, so that userspace
> doesn't have to handle 'change' events?

Yep.

Thanks,

-- 
Anton Vorontsov
email: cbouatmailru@...il.com
irc://irc.freenode.net/bd2
--
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/