linux-kernel - Re: [PATCH RFC] drivers/core: Replace lockdep_set_novalidate

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]

Message-ID: <Y+hYn6uzIUBaxDdV@moria.home.lan>
Date:   Sat, 11 Feb 2023 22:10:23 -0500
From:   Kent Overstreet <kent.overstreet@...ux.dev>
To:     Alan Stern <stern@...land.harvard.edu>
Cc:     Kent Overstreet <kent.overstreet@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Coly Li <colyli@...e.de>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        syzkaller <syzkaller@...glegroups.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Boqun Feng <boqun.feng@...il.com>,
        LKML <linux-kernel@...r.kernel.org>,
        USB list <linux-usb@...r.kernel.org>,
        Hillf Danton <hdanton@...a.com>
Subject: Re: [PATCH RFC] drivers/core: Replace lockdep_set_novalidate_class()
 with unique class keys

On Sat, Feb 11, 2023 at 10:03:11PM -0500, Alan Stern wrote:
> On Sat, Feb 11, 2023 at 09:46:42PM -0500, Kent Overstreet wrote:
> > On Sat, Feb 11, 2023 at 09:40:58PM -0500, Alan Stern wrote:
> > > Or maybe you're referring to what this patch does?  It does indeed 
> > > create a bunch of dynamic classes -- one for each struct device.  The 
> > > ordering rules derived by lockdep will be somewhat arbitrary, as you 
> > > say.  But some of them certainly will be related to the structure of the 
> > > source code.
> > 
> > I could be :) I haven't been able to find the patch in question - have a
> > link?
> 
> It was earlier in this email thread.  Here's a link:
> 
> https://lore.kernel.org/r/Y+gLd78vChQERZ6A@rowland.harvard.edu/
> 
> > If you're talking about making lock_class_key dynamic, I think I stand
> > by what I said though - OTOH, if all you're doing is lifting that to the
> > caller of the device object init function, so it'll still be a static
> > object in the driver, that would be totally fine.
> 
> The patch does the first, not the second.  Feel free to object some 
> more...  :-)

So IMO the more correct way to do this would be to change
device_initialize() to __device_initialize(), have it take a
lock_class_key as a parameter, and then use __mutex_init() instead of
mutex_init().

But let's think about this more. Will there ever be situations where
lock ordering is dependent on what hardware is plugged into what, or
what hardware is plugged in first?