linux-kernel - Re: [PATCH 1/5] drivercore: add new error value for deferred probe

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 for Android: free password hash cracker in your pocket

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

Date:	Sun, 9 Oct 2011 18:06:56 -0700
From:	Greg KH <greg@...ah.com>
To:	Grant Likely <grant.likely@...retlab.ca>
Cc:	Valdis.Kletnieks@...edu, "G, Manjunath Kondaiah" <manjugk@...com>,
	linux-arm-kernel@...ts.infradead.org, linux-omap@...r.kernel.org,
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
	Dilan Lee <dilee@...dia.com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Manjunath GKondaiah <manjunath.gkondaiah@...aro.org>,
	Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH 1/5] drivercore: add new error value for deferred probe

On Sun, Oct 09, 2011 at 04:59:31PM -0600, Grant Likely wrote:
> On Fri, Oct 7, 2011 at 6:12 PM, Greg KH <greg@...ah.com> wrote:
> > On Fri, Oct 07, 2011 at 07:28:33PM -0400, Valdis.Kletnieks@...edu wrote:
> >> On Fri, 07 Oct 2011 16:12:45 MDT, Grant Likely said:
> >> > On Fri, Oct 7, 2011 at 12:43 AM, Greg KH <greg@...ah.com> wrote:
> >> > > On Fri, Oct 07, 2011 at 10:33:06AM +0500, G, Manjunath Kondaiah wrote:
> >>
> >> > >> +#define EPROBE_DEFER 517     /* restart probe again after some time */
> >> > >
> >> > > Can we really do this?
> >>
> >> > According to Arnd, yes this is okay.
> >>
> >> > >  Isn't this some user/kernel api here?
> >>
> >> > > What's wrong with just "overloading" on top of an existing error code?
> >> > > Surely one of the other 516 types could be used here, right?
> >>
> >> > overloading makes it really hard to find the users at a later date.
> >>
> >> Would proposing '#define EPROBE_DEFER EAGAIN' be acceptable to everybody? That
> >> would allow overloading EAGAIN, but still make it easy to tell the usages apart
> >> if we need to separate them later...
> >
> > Yes, please do that, it is what USB does for it's internal error code
> > handling.
> 
> Really?  When we've only currently used approximately 2^9 of a 2^31
> numberspace?  I'm fine with making sure that the number doesn't show
> up in the userspace headers, but it makes no sense to overload the
> #defines.  Particularly so in this case where it isn't feasible to
> audit every driver to figure out what probe might possibly return.  It
> is well within the realm of possibility that existing drivers are
> already returning -EAGAIN.

I doubt they are, but you are right, it's really hard to tell.

> Besides; linux/errno.h *already* has linux-internal error codes that
> do not get exported out to userspace.  There is an #ifdef __KERNEL__
> block around ERESTARTSYS through EIOCBRETRY which is filtered out when
> exporting headers.  I can't see any possible reason why we wouldn't
> add Linux internal error codes here.

As long as it stays internal, that's fine, I was worried that this would
be exported to userspace.

Alan, still object to this?

greg k-h
--
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/