linux-kernel - Re: [RFC 09/16] kgr: mark task

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:	Thu, 1 May 2014 22:17:44 +0200 (CEST)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Tejun Heo <tj@...nel.org>
cc:	Jiri Slaby <jslaby@...e.cz>, linux-kernel@...r.kernel.org,
	jirislaby@...il.com, Vojtech Pavlik <vojtech@...e.cz>,
	Michael Matz <matz@...e.de>,
	Steven Rostedt <rostedt@...dmis.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...hat.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Theodore Ts'o <tytso@....edu>,
	Dipankar Sarma <dipankar@...ibm.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Subject: Re: [RFC 09/16] kgr: mark task_safe in some kthreads

On Thu, 1 May 2014, Tejun Heo wrote:

> > Some threads do not use kthread_should_stop. Before we enable a
> 
> Haven't really following kgraft development but is it safe to assume
> that all kthread_should_stop() usages are clean side-effect-less
> boundaries?  If so, why is that property guaranteed?  Is there any
> mechanism for sanity checks?  Maybe I'm just failing to understand how
> the whole thing is supposed to work but this looks like it could
> devolve into something more broken than the freezer which we haven't
> fully recovered from yet.

Hi Tejun,

first, thanks a lot for review.

I agree that this expectation might really somewhat implicit and is not 
probably properly documented anywhere. The basic observation is "whenever 
kthread_should_stop() is being called, all data structures are in a 
consistent state and don't need any further updates in order to achieve 
consistency, because we can exit the loop immediately here", as 
kthread_should_stop() is the very last thing every freezable kernel thread 
is calling before starting a new iteration.

For the sake of collecting data points -- do you happen to have any 
counter-example to the assumption?

Thanks,

-- 
Jiri Kosina
SUSE Labs
--
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/