On 14/06/12 08:30, Andrew Morton wrote:
> On Thu, 14 Jun 2012 08:14:49 +0100 Lee Jones<[email protected]> wrote:
>
>> On 13/06/12 23:25, Andrew Morton wrote:
>>> On Tue, 12 Jun 2012 09:57:37 +0100
>>> Lee Jones<[email protected]> wrote:
>>>
>>>> The kernel now forces IRQs to be ONESHOT if no IRQ handler is passed.
>>>
>>> What does this mean. The kernel crashes? The registration fails? A
>>> warning is emitted?
>>>
>>> When fixing a bug, please fully describe the consequences of that bug.
>>>
>>>> Cc: [email protected]
>>>
>>> Especially when suggesting a -stable backport.
>>
>> No problem. I'll try to remember that for next time.
>>
>> I see that you've taken the patch into your tree however. So do you want
>> me to update the commit log and resubmit, or are you going to 'let this
>> one slide'?
>
> Please read my emails - they're very nice! "What does this mean. The
> kernel crashes? The registration fails? A warning is emitted?". You
> answer that, I copy-n-paste into changelog and we're done.
Ah, you're a star!
Registration fails:
> __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
> {
<snip>
> if (new->flags & IRQF_ONESHOT) {
<snip>
> } else if (new->handler == irq_default_primary_handler) {
> /*
> * The interrupt was requested with handler = NULL, so
> * we use the default primary handler for it. But it
> * does not have the oneshot flag set. In combination
> * with level interrupts this is deadly, because the
> * default primary handler just wakes the thread, then
> * the irq lines is reenabled, but the device still
> * has the level irq asserted. Rinse and repeat....
> *
> * While this works for edge type interrupts, we play
> * it safe and reject unconditionally because we can't
> * say for sure which type this interrupt really
> * has. The type flags are unreliable as the
> * underlying chip implementation can override them.
> */
> pr_err("Threaded irq requested with handler=NULL and !ONESHOT
> for irq %d\n", irq);
> ret = -EINVAL;
> goto out_mask;
> }
<snip>
--
Lee Jones
Linaro ST-Ericsson Landing Team Lead
M: +44 77 88 633 515
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