Re: [RFC PATCH v1.9 05/14] sched: horrible way to detect whether a task has been preempted

From	Josh Poimboeuf <jpoimboe@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [RFC PATCH v1.9 05/14] sched: horrible way to detect whether a task has been preempted
Date	2016-04-08 16:40 +0200
Message-ID	<rlFJL-5dc-11@gated-at.bofh.it> (permalink)
References	(2 earlier) <rkVnz-4fv-7@gated-at.bofh.it> <rkYEO-6IT-5@gated-at.bofh.it> <rleJB-1Ne-41@gated-at.bofh.it> <rljgf-5hz-25@gated-at.bofh.it> <rlzEl-Px-1@gated-at.bofh.it>
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On Fri, Apr 08, 2016 at 10:07:10AM +0200, Petr Mladek wrote:
> On Thu 2016-04-07 09:34:03, Josh Poimboeuf wrote:
> > On Thu, Apr 07, 2016 at 11:47:00AM +0200, Petr Mladek wrote:
> > > On Wed 2016-04-06 11:33:56, Josh Poimboeuf wrote:
> > > > On Wed, Apr 06, 2016 at 03:06:19PM +0200, Petr Mladek wrote:
> > > We could even move this check into the livepatch code but then
> > > print_context_stack_reliable() will not always give reliable results.
> > 
> > Why would moving the check to the livepatch code affect the reliability
> > of print_context_stack_reliable()?
> 
> print_context_stack_reliable() is a generic function that might
> eventualy be used also outside livepatch code. If there is
> preempt_schedule_irq() on the stack, it means that the rest
> of the stack might be unreliable and it should be detected
> by the function itself.

Ah, I see now.  I actually thought you meant something else (moving
in_preempt_schedule_irq() itself to livepatch code, but still calling it
from print_context_stack_reliable()).

> Let's forget the idea of moving the check into the livepatch
> code :-)

Agreed :-)

-- 
Josh

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Re: [RFC PATCH v1.9 05/14] sched: horrible way to detect whether a  task has been preempted Petr Mladek <pmladek@suse.com> - 2016-04-06 15:10 +0200
  Re: [RFC PATCH v1.9 05/14] sched: horrible way to detect whether a  task has been preempted Josh Poimboeuf <jpoimboe@redhat.com> - 2016-04-06 18:40 +0200
    Re: [RFC PATCH v1.9 05/14] sched: horrible way to detect whether a  task has been preempted Petr Mladek <pmladek@suse.com> - 2016-04-07 11:50 +0200
      Re: [RFC PATCH v1.9 05/14] sched: horrible way to detect whether a  task has been preempted Josh Poimboeuf <jpoimboe@redhat.com> - 2016-04-07 16:40 +0200
        Re: [RFC PATCH v1.9 05/14] sched: horrible way to detect whether a  task has been preempted Petr Mladek <pmladek@suse.com> - 2016-04-08 10:10 +0200
          Re: [RFC PATCH v1.9 05/14] sched: horrible way to detect whether a  task has been preempted Josh Poimboeuf <jpoimboe@redhat.com> - 2016-04-08 16:40 +0200

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