linux-kernel - Re: [PATCH] genirq: Check irq disabled & masked states in irq

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Date:   Wed, 31 May 2017 11:22:14 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Brian Norris <briannorris@...omium.org>
cc:     jeffy <jeffy.chen@...k-chips.com>,
        LKML <linux-kernel@...r.kernel.org>, dianders@...omium.org,
        tfiga@...omium.org, Johannes Berg <johannes.berg@...el.com>
Subject: Re: [PATCH] genirq: Check irq disabled & masked states in
 irq_shutdown

On Tue, 30 May 2017, Brian Norris wrote:
> On Sat, May 27, 2017 at 10:16:37AM +0200, Thomas Gleixner wrote:
> > On Sat, 27 May 2017, jeffy wrote:
> > > for example when a driver(drivers/net/wireless/marvell/mwifiex/main.c) try to
> > > do these:
> > > 
> > > devm_request_irq->irq_startup->irq_enable
> > > disable_irq                                     <-- disabled and masked
> > > devm_free_irq->irq_shutdown                     <-- disable it again
> > 
> > This driver is broken as hell.
> 
> No argument on the general statement :)
> 
> > It requests the interrupt _BEFORE_ the whole
> > thing is initialized. If there is a pending interrupt on that line, it will
> > explode nicely before it is able to disable the irq. But that's a different
> > problem.
> 
> For that particular interrupt, it's mostly an informational interrupt
> regarding wakeups. We don't do anything that could blow up there, except
> report a (spurious) wakeup event. (And this spurious wakeup event only
> occurs because the Wifi firmware may toggle its "wake" pin even when the
> system is already awake. A weird behavior...)
> 
> So yes, the pattern isn't great, but no, it's not going to blow up,
> AFAIK.

Fair enough.

Thanks,

	tglx