linux-kernel - Re: [PATCH 4/5] workqueue: don't expose workqueue

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:	Wed, 13 May 2015 09:52:54 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Lai Jiangshan <laijs@...fujitsu.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] workqueue: don't expose workqueue_attrs to users

Hello, Lai.

On Wed, May 13, 2015 at 09:43:19AM +0800, Lai Jiangshan wrote:
> >> I think the workqueue.c has too much complicated and rarely used APIs
> >> and exposes too much in this way.  No one can set the nice value
> >> and the cpuallowed of a task atomically.
> > 
> > What do you mean no one can?
> 
> normal/general task. not kworker.
> 
> no one can set the nice value and the cpumallowed of a normal task atomically.
> 
> The kernel doesn't have such APIs:
> 
> lock_and_get_task_cpus_allowed(task);
> /* modify cpumask */
> set_cpus_allowed_ptr_and_unlock();

I'm still not following.  What are you trying to say?

> > So, we're now requiring workqueue users to take care of
> > synchronization, disabling and reinstating WQ_SYSFS (what if userland
> > hits those knobs at the same time?) 
> 
> I think there is no userland knobs when !WQ_SYSFS.

So, fail apply attrs calls if the workqueue is exposed to userland?
Are you serious?

> > and poking into workqueue struct to determine the current values of the
> 
> I think the copy version of cpumask, nice, numa values are same as
> the workqueue struct have. No poking is required.
> (Its own lock-protect-region is the ONLY entry to call apply_workqueue_attrs()).

And how would the caller know the current values?

Thanks.

-- 
tejun
--
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/