Re: cpufreq + PREEMPT_RT_FULL give bad context sleeping BUG

[Gregoire Gentil <gregoire@gentil.com>]

On 03/26/2013 02:44 PM, Thomas Gleixner wrote:
> On Tue, 26 Mar 2013, Thomas Gleixner wrote:
>
>> On Tue, 26 Mar 2013, Sebastian Andrzej Siewior wrote:
>>
>>> * Thomas Gleixner | 2013-03-26 22:07:45 [+0100]:
>>>
>>>>> that means it should trigger on mainline as well.
>>>>
>>>> No. It won't. Mainline uses a spinlock which gets converted to a
>>>> sleeping spinlock on rt.
>>>>
>>>>   (rt_spin_lock+0x30/0x64) from (clk_get_rate+0x30/0x54)
>>>
>>> This is true but this spinlock in only available in the OOT code
>>> Gregoire Gentil pointed out ([0]). In mainline we have a mutex in
>>> drivers/clk/clk.c and this is what my omap4 blaze is using.
>>>
>>> [0] http://dev.omapzoom.org/?p=integration/kernel-ubuntu.git;a=blob;f=arch/arm/plat-omap/clock.c;h=8c0e8fe2c5c51673e41e4304194d922dbfaedf38;hb=3e1c9f139425663ceee48f92e8d3f23158580334
>>
>> Yeah, it's that way in mainline as well.
>
> I meant, that the mutex is taken. So yes, this will cause a warning in
> !RT too.
Hello,

So what could be a tentative solution? Could you advise what I could try?

Many thanks in advance,

Grégoire

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