Re: lockdep and threaded IRQs (was: ...)

Thomas Gleixner
2009-02-28T20:56:25Z

On Sat, 28 Feb 2009, David Brownell wrote:
> Got a version that applies to mainline GIT?

http://tglx.de/~tglx/patches.tar.bz2

> At a quick glance it looks like these patches don't cover
> set_irq_chained_handler(), which would be trouble since
> __setup_irq() doesn't get called in those cases.

Hmm, I did not think about chained handlers where the demux handler
needs to run in a thread as well. Usually demux handlers just have a
fast path kicking the particular real handlers.

> They should however handle simpler cases, like I2C devices
> that only expose one IRQ instead of needing to demux several
> dozen IRQs going to different drivers and subsystems.
>
> And, not touching lockdep, the original ugliness will still
> be needed (re-enabling IRQs in threaded handlers).

Err ? The threaded handlers run with interrupts enabled.

static int irq_thread(void *data)
{
...

while (!kthread_should_stop()) {
set_current_state(TASK_INTERRUPTIBLE);
if (irq_thread_should_run(action) && current->irqaction) {
__set_current_state(TASK_RUNNING);
action->handler(action->irq, action->dev_id);
} else
schedule();
}

Thanks,

tglx