On Thu, Jul 22, 2010 at 12:44 PM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> 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 ???
I double faulted; my apologies. We're using kernel 2.6.33.5
with corresponding 2.6.33.5-rt25 patches.
>> > 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@xxxxxxxxxx>
>>
>> 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.
Although the patch does compile for us, we do see, as you predicted, a
problem in queue_work:
-----
[ 42.879547] BUG: sleeping function called from invalid context at
kernel/rtmutex.c:684
[ 42.879577] pcnt: 2 0 in_atomic(): 1, irqs_disabled(): 128, pid:
228, name: modprobe
[ 42.879638] [<c0044490>] (unwind_backtrace+0x0/0xe8) from
[<c04cb50c>] (rt_spin_lock+0x30/0x5c)
[ 42.879669] [<c04cb50c>] (rt_spin_lock+0x30/0x5c) from [<c007c0ec>]
(__queue_work+0x10/0x2c)
[ 42.879669] [<c007c0ec>] (__queue_work+0x10/0x2c) from [<c007c164>]
(queue_work_on+0x44/0x5c)
[ 42.879699] [<c007c164>] (queue_work_on+0x44/0x5c) from
[<c032e3f8>] (twl4030_sih_set_type+0x84/0xd0)
[ 42.879730] [<c032e3f8>] (twl4030_sih_set_type+0x84/0xd0) from
[<c00aa944>] (__irq_set_trigger+0x34/0x88)
[ 42.879760] [<c00aa944>] (__irq_set_trigger+0x34/0x88) from
[<c00ab2ec>] (__setup_irq+0x34c/0x3c0)
[ 42.879791] [<c00ab2ec>] (__setup_irq+0x34c/0x3c0) from
[<c00ab430>] (request_threaded_irq+0xd0/0x148)
[ 42.879821] [<c00ab430>] (request_threaded_irq+0xd0/0x148) from
[<bf027770>] (twl_rtc_probe+0x104/0x1fc [rtc_twl])
[ 42.879852] [<bf027770>] (twl_rtc_probe+0x104/0x1fc [rtc_twl]) from
[<c0324e2c>] (platform_drv_probe+0x18/0x1c)
...
------
> (/me
> mentions, that todo list is already overly full, so do not expect
> wonders).
Understood. We'd be happy to be guinea pigs!
Thanks,
Jeremy
> Thanks,
>
> tglx
>
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