[linux-dvb] [BUG] flexcop lockdep

Antti Seppälä ajhseppa at niksula.hut.fi
Thu Apr 5 21:57:26 CEST 2007


Patrick Boettcher wrote:
> On Thu, 5 Apr 2007, Borgi2008 wrote:
> 
>> Am Mittwoch, den 04.04.2007, 23:29 +0300 schrieb Antti Seppälä:
>>> Borgi2008 wrote:
>>>> Hello,
>>>>
>>>> i've created a bugfixes. Hope it could helps you.
>>>>
>>>> Hendrik Borghorst
>>>>
>>>>
>>> Actually, looking at the code I cannot figure out why there has to be a
>>> spinlock in the first place.
>>>
>>> The lock is only taken in the interrupt handler which already runs in
>>> atomic context so there is no use in making the handler protected by a
>>> spinlock. Am I missing something here?
>>>
>>> I think the spinlock is unnecessary and should be removed entirely.
> 
> Even on SMP systems? ISRs are only atomic on one CPU.
> 
> Patrick.

Apparently I've used to thinking too much in the UP world.

It seems that flexcop interrupts are not acked with a special register
write so an interrupt can then occur even while it is being processed on
another CPU.(?)

In that case the patch from Hendrik is correct.


-- 
Antti Seppälä



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