Messages in this thread | | | Date | Mon, 26 Jun 2017 14:22:51 +0800 | From | jeffy <> | Subject | Re: [PATCH v3] genirq: Check irq disabled & masked states in irq_shutdown |
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Hi Thomas Gleixner,
On 05/31/2017 07:02 AM, Thomas Gleixner wrote: > On Mon, 29 May 2017, jeffy.chen wrote: >> 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. ok > > 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. i saw your patches landed, so i sent a patch for enable/disable/unmask/mask_irq, please help to review :) > > Thanks, > > tglx > > > > > > > > > > > >
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