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:	Sat, 12 Dec 2009 18:35:40 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Zhang Rui <rui.zhang@...el.com>,
	LKML <linux-kernel@...r.kernel.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>
Subject: Re: Async suspend-resume patch w/ completions (was: Re: Async suspend-resume patch w/ rwsems)

On Saturday 12 December 2009, Alan Stern wrote:
> On Sat, 12 Dec 2009, Rafael J. Wysocki wrote:
> 
> > Below is a patch I've just tested, but there's a lockdep problem in it I don't
> > know how to solve.  Namely, lockdep is apparently unhappy with us not releasing
> > the lock taken in device_suspend() and it complains we take it twice in a row
> > (which we do, but for another device).  I need to use down_read_non_owner()
> > to make it shut up and then I also need to use up_read_non_owner() in
> > __device_suspend(), although there's the comment in include/linux/rwsem.h
> > saying exatly this about that:
> > 
> > /*
> >  * Take/release a lock when not the owner will release it.
> >  *
> >  * [ This API should be avoided as much as possible - the
> >  *   proper abstraction for this case is completions. ]
> >  */
> > 
> > (I'd like to know your opinion about that).  Yet, that's not all, because next
> > it complains during resume that __device_resume() releases a lock it didn't
> > acquire, which it clearly does, but that is intentional.  Unfortunately,
> > there's no up_write_non_owner() ...
> 
> Hah!  I knew it!
> 
> How come lockdep didn't complain earlier?  What's different about this 
> patch?  Only the nesting annotations?  Why should adding annotations 
> make lockdep less happy?

I'm not sure.  Perhaps I made a mistake during the previous tests.

Rafael
--
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/

Powered by blists - more mailing lists