On Mon, 29 May 2017, jeffy.chen wrote:ok
i think if we want to make all irq enable/disable balance, maybe we can:
1/ only call irq_enable/disable from enable/disable_irq(change other
irq_enable/disable to enable/disable_irq), so they would be protected by the
refcnt(deph)
You cannot call enable/disable_irq() from places which call
irq_enable/disable() due to locking reasons.
__disable_irq()/__enable_irq() can/must be called with desc->lock held, but
__enable_irq() does more than just calling irq_enable().
So no, it's not that simple.
2/ disable lazy stuff in irq_shoutdown(we already did this in free_irq)
No, irq_shutdown() is called from other places as well.
3/ in irq_shutdown, set depth to 0 if it's not disabled and masked(for lazy stuff)
before calling disable_irq,
Uurgh, no. That's a unholy hack.
So what should be done to fix this is to make consequent use of the state bits.
irq_disable()
if (irqd_irq_disabled())
return;
irqd_set_irq_disabled();
....
This should be done for both mask/unmask disable/enable. You get the idea.
i saw your patches landed, so i sent a patch for enable/disable/unmask/mask_irq, please help to review :)
We probably want a third state bit for STARTED_UP and do the same dance in
startup/shutdown as well. Which brings me to a different issue, which is
outside the scope of your problem, but looking at the code made me find it.
If a interrupt is marked IRQ_NOAUTOEN then request_irq() will not invoke
irq_startup(). The interrupt is just completely set up, but stays disabled.
It is enabled later via enable_irq(). That works so far with no complaints,
but there is an interesting twist:
In that NOAUTOEN case nothing ever calls irq_startup() on that irq, which
means that in case the irq_chip has a irq_startup() callback nothing will
invoke it and also irq_domain_activate_irq() will never be invoked on such
an irq.
Looks like all implementations which use IRQ_NOAUTOEN are not sensitive to
that. It's been broken forever.
Fixing this needs the extra state bit IRQD_ STARTED_UP as we cannot reuse
the IRQD_ACTIVATED bit because some of the interrupts are actually
activated before they are requested.
Too tired to fix that now, but I'll have a look tomorrow. Once this is
fixed, you can add the extra bits to prevent this disable/enable calls
which cause the imbalance deeper down.
Thanks,
tglx