linux-kernel - Re: [PATCH] PCI: let pci_request_irq properly deal with threaded interrupts

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Date:   Tue, 31 Jul 2018 00:50:21 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Bjorn Helgaas <helgaas@...nel.org>
cc:     Heiner Kallweit <hkallweit1@...il.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
        Christoph Hellwig <hch@....de>, linux-kernel@...r.kernel.org,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Russell King <linux@...linux.org.uk>,
        Sebastian Reichel <sre@...nel.org>, Milo Kim <milo.kim@...com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Lee Jones <lee.jones@...aro.org>
Subject: Re: [PATCH] PCI: let pci_request_irq properly deal with threaded
 interrupts

On Mon, 30 Jul 2018, Bjorn Helgaas wrote:

> [+cc maintainers of possibly erroneous callers of request_threaded_irq()]
> 
> On Mon, Jul 30, 2018 at 04:30:28PM -0500, Bjorn Helgaas wrote:
> > [+cc Thomas, Christoph, LKML]
> > 
> > On Mon, Jul 30, 2018 at 12:03:42AM +0200, Heiner Kallweit wrote:
> > > If we have a threaded interrupt with the handler being NULL, then
> > > request_threaded_irq() -> __setup_irq() will complain and bail out
> > > if the IRQF_ONESHOT flag isn't set. Therefore check for the handler
> > > being NULL and set IRQF_ONESHOT in this case.
> > > 
> > > This change is needed to migrate the mei_me driver to
> > > pci_alloc_irq_vectors() and pci_request_irq().
> > > 
> > > Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
> > 
> > I'd like an ack from Thomas because this requirement about IRQF_ONESHOT
> > usage isn't mentioned in the request_threaded_irq() function doc or
> > Documentation/
> 
> Possibly these other request_threaded_irq() callers are similarly
> broken?  I can't tell for sure about tda998x_create(), but all the
> others certainly call request_threaded_irq() with "handler == NULL"
> and irqflags that do not contain IRQF_ONESHOT:
> 
>   max8997_muic_probe()
>     request_threaded_irq(virq, NULL, ..., IRQF_NO_SUSPEND, ...)
> 
>   tda998x_create()
>     request_threaded_irq(client->irq, NULL, ..., irqd_get_trigger_type(), ...)
>     (I can't tell what irqd_get_trigger_type() does)

It reads the trigger type back from the irq chip (level/edge/polarity) but
does not return with the ONESHOT bit set.

>   ab8500_btemp_probe()
>   ab8500_charger_probe()
>     request_threaded_irq(irq, NULL, ..., IRQF_SHARED | IRQF_NO_SUSPEND, ...)

SHARED is interesting ....

>   lp8788_set_irqs()
>     request_threaded_irq(virq, NULL, ..., 0, ...)
> 
>   max77686_rtc_probe()
>     request_threaded_irq(info->virq, NULL, ..., 0, ...)
> 
>   wm8350_register_irq()
>     request_threaded_irq(irq + wm8350->irq_base, NULL, ..., flags, ...)
>     (I think all callers of wm8350_register_irq() supply 0 for "flags")

Indeed. This all looks pretty much wrong. No idea why nobody ever noticed.

Thanks,

	tglx