From: Jesse Barnes <jbarnes@virtuousgeek.org>
To: Jean Delvare <khali@linux-fr.org>
Cc: Greg KH <greg@kroah.com>, Milton Miller <miltonm@bga.com>,
Michael Ellerman <michael@ellerman.id.au>,
linux-kernel <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-pci@vger.kernel.org
Subject: Re: [PATCH/RFC] pci: dynids.use_driver_data considered harmful
Date: Fri, 15 Aug 2008 10:46:59 -0700 [thread overview]
Message-ID: <200808151046.59590.jbarnes@virtuousgeek.org> (raw)
In-Reply-To: <20080815175014.2e005377@hyperion.delvare>
> > It's pretty "trivial" to look to see if the field is set in the pci_id
> > structure, that should be all that is needed, right?
>
> Well... If you consider that all drivers using the driver_data field
> should have the dynids.use_driver_data flag set unconditionally and
> without looking at the code, then in fact you agree with Milton and
> myself that this flag should be dropped. The whole point of the flag,
> if my guess is correct, was to hint the developer that he/she should
> double check his/her code before setting the flag. If you set it for
> all these drivers, then all it does is preventing users from passing a
> driver_data value to drivers which do _not_ use the driver_data... but
> doing that has zero effect at the moment, so that wouldn't actually be
> any different from dropping dynids.use_driver_data altogether.
>
> So I have to reiterate my support to Milton's idea of dropping
> the dynids.use_driver_data flag. It does more harm than good.
Yeah it doesn't seem to be very heavily used at this point. :)
I see around 400 uses of id->driver_data right now, and only 2 of
use_driver_data. If we remove the use_driver_data field, drivers (except for
the 2 using the field) will start to see whatever values userspace passes to
them rather than 0, and at least in some of the few cases I looked at that
could cause breakage due to out of bounds references.
So I think your point about dynamic IDs in general is a good one; this flag
really does look like an "audit was done" bit, but doesn't go as far is it
should.
The patch you posted to forbid dynamic binding unless use_driver_data is iset
is probably the safest thing to do, given that drivers that *don't* set
use_driver_data look like they might misbehave even with a driver_data value
of 0...
What do you think, Greg? Convinced yet? :)
Thanks,
Jesse
next prev parent reply other threads:[~2008-08-15 17:47 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-10 21:12 [RFC] (almost) booting allyesconfig -- please don't poke super-io without request_region Milton Miller
2008-07-10 21:14 ` mtd: remove __PPC__ hardcoded address from nand/diskonchip and devices/docprobe Milton Miller
2008-07-10 21:33 ` [lm-sensors] [RFC] (almost) booting allyesconfig -- please don't poke super-io without request_region Hans de Goede
2008-07-10 21:51 ` Milton Miller
2008-07-11 6:52 ` Jean Delvare
2008-07-11 7:27 ` Hans de Goede
2008-07-11 7:36 ` Jean Delvare
2008-07-13 6:31 ` Hans de Goede
2008-07-13 21:11 ` [lm-sensors] " David Hubbard
2008-07-13 21:22 ` Hans de Goede
2008-07-13 21:26 ` David Hubbard
2008-07-14 7:59 ` Jean Delvare
2008-07-14 17:09 ` Milton Miller
2008-07-14 17:30 ` [lm-sensors] " Hans de Goede
2008-07-14 17:55 ` David Hubbard
2008-07-15 8:36 ` Jean Delvare
2008-07-15 15:31 ` David Hubbard
2008-07-16 7:46 ` Jean Delvare
2008-07-16 8:09 ` Rene Herman
2008-07-15 8:28 ` Jean Delvare
[not found] ` <for-27-patch9@bga.com>
2008-07-12 20:02 ` [PATCH/RESEND] pci: dynids.use_driver_data considered harmful Milton Miller
2008-07-12 20:17 ` Greg KH
2008-07-12 20:58 ` Jean Delvare
2008-07-12 21:17 ` Milton Miller
2008-07-12 21:29 ` Milton Miller
[not found] ` <20080712041137.GA5933@kroah.com>
2008-07-12 21:08 ` [PATCH/RFC] " Milton Miller
2008-07-12 22:48 ` Milton Miller
2008-07-16 10:18 ` Milton Miller
2008-07-17 7:07 ` Greg KH
2008-07-17 14:36 ` Milton Miller
2008-08-06 7:31 ` Jean Delvare
2008-08-14 22:12 ` Greg KH
2008-08-15 14:50 ` Milton Miller
2008-08-15 15:50 ` Jean Delvare
2008-08-15 17:46 ` Jesse Barnes [this message]
2008-08-15 18:55 ` Jean Delvare
2008-08-15 19:15 ` Jesse Barnes
2008-08-16 6:22 ` Greg KH
2008-08-17 19:06 ` Jean Delvare
2008-08-18 3:50 ` Greg KH
2008-08-18 17:13 ` Jesse Barnes
2008-08-18 20:41 ` Jesse Barnes
2008-08-19 18:01 ` Milton Miller
2008-08-06 7:22 ` Jean Delvare
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