Re: [RFC 09/16] kgr: mark task_safe in some kthreads

From: Tejun Heo <tj@kernel.org>
To: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Vojtech Pavlik <vojtech@suse.cz>, Jiri Slaby <jslaby@suse.cz>,
	Jiri Kosina <jkosina@suse.cz>,
	linux-kernel@vger.kernel.org, jirislaby@gmail.com,
	Michael Matz <matz@suse.de>, Steven Rostedt <rostedt@goodmis.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	Ingo Molnar <mingo@redhat.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Theodore Ts'o" <tytso@mit.edu>,
	Dipankar Sarma <dipankar@in.ibm.com>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Subject: Re: [RFC 09/16] kgr: mark task_safe in some kthreads
Date: Thu, 15 May 2014 00:50:11 -0400	[thread overview]
Message-ID: <20140515045011.GB3825@htj.dyndns.org> (raw)
In-Reply-To: <1400129178.5175.82.camel@marge.simpson.net>

Hello, Mike.

On Thu, May 15, 2014 at 06:46:18AM +0200, Mike Galbraith wrote:
> > I think it'd be healthier to identify the use cases and then provide
> > proper interface for it.  Note that workqueue can now expose interface
> > to modify concurrency, priority and cpumask to userland which
> > writeback workers are already using.
> 
> You can't identify a specific thing, any/all of it can land on the
> user's diner plate, so he should be able to make the decisions.  Power
> to the user and all that, if he does something stupid, tuff titty.  User
> getting to call the shots, and getting to keep the pieces when he fscks
> it all up is wonderful stuff, lets kernel people off the hook :)

Do we know specific kthreads which need to be exposed with this way?
If there are good enough reasons for specific ones, sure, but I don't
think "we can't change any of the kthreads because someone might be
diddling with it" is something we can sustain in the long term.

Thanks.

-- 
tejun