lkml.org 
[lkml]   [2013]   [Feb]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: Debugging Thinkpad T430s occasional suspend failure.
From
2013/2/17 Frederic Weisbecker <fweisbec@gmail.com>:
> 2013/2/17 Linus Torvalds <torvalds@linux-foundation.org>:
>> On Sun, Feb 17, 2013 at 7:11 AM, Frederic Weisbecker <fweisbec@gmail.com> wrote:
>>>
>>> preempt_value_in_interrupt() looks buggy in your patch: it makes
>>> invoke_softirq() returning if (val & HARDIRQ_MASK). But that's always
>>> true since you have moved further the sub_preempt_count(IRQ_EXIT)
>>> further.
>>
>> No, that's not it. The value hasn't been written back yet, but it already did:
>>
>> + int offset = IRQ_EXIT_OFFSET;
>> + int count = preempt_count() - offset;
>>
>> so the 'count' has the IRQ_EXIT_OFFSET already subtracted. So no,
>> HARDIRQ_MASK is *not* always set.
>
> Another thing. Perhaps we can push the idea of your patch a little
> further by re-entering HARDIRQ_OFFSET at the end of the softirq
> processing and do the final sub_preempt_count(HARDIRQ_OFFSET) at the
> very end of irq_exit().
>
> This way irq_exit() looks a bit more simple to me: everything there
> becomes considered as in hardirq: (ie: rcu_irq_exit() and
> tick_nohz_irq_exit() won't appear anymore as weird special cases) and
> we get rid of that IRQ_EXIT_OFFSET hack that fixes the CONFIG_PREEMPT
> case.
>
> I'm attaching an untested patch that modify yours. It's probably
> missing some corner cases that rely on in_interrupt() value in
> rcu_irq_exit() and tick_nohz_irq_exit() and may be other things.

I messed up preempt_offset_in_interrupt() with in_atomic() code
instead of in_interrupt(). Anyway the patch is untested and is more
there to get your opinion for now. I'll put some more care on it if
people like it.


\
 
 \ /
  Last update: 2013-02-17 22:21    [W:0.210 / U:0.120 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site