Re: Trouble booting PREEMPT_RT kernel on ARM platform, 2.6.33

[Jeremy Brown <jhbrown@repinvariant.com>]

Whoops, trying this again without HTML, sorry for any double-sends:

On Thu, Jul 22, 2010 at 9:44 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
>
> On Wed, 21 Jul 2010, gowrishankar wrote:
>
> > On Wednesday 21 July 2010 03:56 AM, Jeremy Brown wrote:
> > > We're trying to get a PREEMPT_RT kernel running on a BeagleBoard C4
> > > (OMAP3 Arm architecture).  We're using kernel version 2.6.33, with
> > >
> > 2.6.33 ! not 2.6.33.6 ???
> > > patches from
> > > patch-2.6.33.6-rt26.gz
> > >
> > > On boot, we start seeing messages of this form:
> > >
> > > ----
> > > [ 4528.227294] BUG: sleeping function called from invalid context at
> > > kernel/rtmutex.c:684
> > > [ 4528.227294] pcnt: 1 0 in_atomic(): 1, irqs_disabled(): 128, pid:
> > > 223, name: modprobe
> > > [ 4528.227355] [<c0044490>] (unwind_backtrace+0x0/0xe8) from
> > > [<c04cb4e4>] (rt_spin_lock+0x30/0x5c)
> > > [ 4528.227386] [<c04cb4e4>] (rt_spin_lock+0x30/0x5c) from [<c032e3b0>]
> > > (twl4030_sih_set_type+0x3c/0xac)
> > >
> > sleeping spin lock is called while preempt/interrupt is disabled.
> >
> > Can you try the below patch ?
> >
> > Signed-off-by: Gowrishankar <gowrishankar.m@in.ibm.com>
> >
> > Index: linux-2.6.33.6-rt26/drivers/mfd/twl4030-irq.c
> > ===================================================================
> > --- linux-2.6.33.6-rt26.orig/drivers/mfd/twl4030-irq.c    2010-07-21
> > 12:40:42.000000000 +0530
> > +++ linux-2.6.33.6-rt26/drivers/mfd/twl4030-irq.c    2010-07-21
> > 12:41:16.000000000 +0530
> > @@ -633,14 +633,14 @@
> >      if (trigger & ~(IRQ_TYPE_EDGE_FALLING | IRQ_TYPE_EDGE_RISING))
> >          return -EINVAL;
> >
> > -    spin_lock_irqsave(&sih_agent_lock, flags);
> > +    raw_spin_lock_irqsave(&sih_agent_lock, flags);
> >      if ((desc->status & IRQ_TYPE_SENSE_MASK) != trigger) {
> >          desc->status &= ~IRQ_TYPE_SENSE_MASK;
> >          desc->status |= trigger;
> >          sih->edge_change |= BIT(irq - sih->irq_base);
> >          queue_work(wq, &sih->edge_work);
> >      }
> > -    spin_unlock_irqrestore(&sih_agent_lock, flags);
> > +    raw_spin_unlock_irqrestore(&sih_agent_lock, flags);
>
> Nope, that's not going to fly. First it does not compile and second
> you trigger the same problem in queue_work() which is called inside
> that section. That needs a bit more work, will have a look. (/me
> mentions, that todo list is already overly full, so do not expect
> wonders).

Hi, Thomas.  Has this has risen to the top of your todo queue?   If
not, we're going to start poking at it here; any thoughts, advice,
and/or pointers to reference material would be greatly appreciated.

If we're fortunate enough to get things working, we'll certainly send
patches to this list.

Thanks,
Jeremy

> Thanks,
>
>        tglx
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