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

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Date:   Mon, 30 Jul 2018 16:30:28 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Heiner Kallweit <hkallweit1@...il.com>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Christoph Hellwig <hch@....de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: let pci_request_irq properly deal with threaded
 interrupts

[+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/

> ---
>  drivers/pci/irq.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/irq.c b/drivers/pci/irq.c
> index 2a808e10..a1de501a 100644
> --- a/drivers/pci/irq.c
> +++ b/drivers/pci/irq.c
> @@ -86,13 +86,17 @@ int pci_request_irq(struct pci_dev *dev, unsigned int nr, irq_handler_t handler,
>  	va_list ap;
>  	int ret;
>  	char *devname;
> +	unsigned long irqflags = IRQF_SHARED;
> +
> +	if (!handler)
> +		irqflags |= IRQF_ONESHOT;
>  
>  	va_start(ap, fmt);
>  	devname = kvasprintf(GFP_KERNEL, fmt, ap);
>  	va_end(ap);
>  
>  	ret = request_threaded_irq(pci_irq_vector(dev, nr), handler, thread_fn,
> -			IRQF_SHARED, devname, dev_id);
> +				   irqflags, devname, dev_id);
>  	if (ret)
>  		kfree(devname);
>  	return ret;
> -- 
> 2.18.0
>