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    SubjectRe: [RFC PATCH 0/3] genirq: mixing IRQF_NO_SUSPEND and wakeup sources on shared IRQs
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    On Thursday, February 26, 2015 07:17:24 PM Boris Brezillon wrote:
    > On Thu, 26 Feb 2015 19:17:03 +0100
    > "Rafael J. Wysocki" <rjw@rjwysocki.net> wrote:
    >
    > > On Thursday, February 26, 2015 04:47:24 PM Boris Brezillon wrote:
    > > > On Thu, 26 Feb 2015 16:44:16 +0100
    > > > "Rafael J. Wysocki" <rjw@rjwysocki.net> wrote:
    >
    > [...]
    >
    > > > >
    > > > > But it is still a bit risky. Namely, if the driver in question is sufficiently
    > > > > broken (eg. it may not suspend the device and rely on the fact that its interrupt
    > > > > handler will be run just because it is sharing a "no suspend" IRQ), we may get
    > > > > an interrupt storm.
    > > > >
    > > > > Isn't that a problem?
    > > >
    > > > For me no (I'll fix all the drivers to handle wakeup, and they are all
    > > > already masking interrupts coming from their side in the suspend
    > > > callback).
    > > > I can't talk for other people though.
    > > > The only problem I see here is that you're not informing people that
    > > > they are erroneously mixing IRQF_NO_SUSPEND and !IRQF_NO_SUSPEND anymore
    > > > (you removed the warning backtrace).
    > > > Moreover, you are replacing their handler by a stub when entering
    > > > suspend, so they might end-up receiving spurious interrupts when
    > > > suspended without knowing why ?
    > > >
    > > > How about checking if the number of actions registered with
    > > > IRQF_NO_SUSPEND + those registered with IRQF_COND_SUSPEND (or another
    > > > flag stating that the handler can safely be called in suspended state
    > > > even if it didn't ask for NO_SUSPEND) are equal to the total number of
    > > > registered actions, and complain if it's not the case.
    > >
    > > The same idea I had while talking to Peter over IRC. So the patch below
    > > implements that.
    >
    > Yep, that's what I had in mind.

    OK, thanks.

    I'll submit it formally, then.


    --
    I speak only for myself.
    Rafael J. Wysocki, Intel Open Source Technology Center.


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