Re: [RFC][PATCH 0/5] preempt_count rework

Andi Kleen
2013-08-14T17:12:23Z

On Wed, Aug 14, 2013 at 06:55:05PM +0200, Peter Zijlstra wrote:
> On Wed, Aug 14, 2013 at 09:48:27AM -0700, Andi Kleen wrote:
>
> > FWIW I removed the user_schedule in v2 because I don't need it anymore.
> > Feel free to pick it up from v1 though.
>
> Ah, I had a quick look through your v2 because I got a link into it from
> Ingo but didn't find it. I'll have to ask Google to locate this v1. I

Sorry, it's the thread starting with

http://permalink.gmane.org/gmane.linux.kernel/1541950

I also pushed the branch to git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-misc.git

uaccess-opt311 is v1
uaccess-opt311-2 is v2 (without user_schedule)

> suppose that's what's wrong with my last patch. It directly does a call
> preempt_schedule -- which I had hoped would work due to its asmlinkage,
> but apparently there's more to it.

preempt_schedule does not preserve registers, so yes that would
explain a lot of problems.

-Andi
--
ak@linux.intel.com -- Speaking for myself only