linux-kernel - Re: [PATCH linux-next v2] arm64: PCI: Introduce pcibios_free

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Date:   Tue, 21 Sep 2021 16:47:31 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Yajun Deng <yajun.deng@...ux.dev>
Cc:     catalin.marinas@....com, will@...nel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH linux-next v2] arm64: PCI: Introduce pcibios_free_irq()
 helper function

On Thu, Aug 26, 2021 at 02:04:06PM +0800, Yajun Deng wrote:
> pcibios_alloc_irq() will be called in pci_device_probe(), but there
> hasn't pcibios_free_irq() in arm64 architecture correspond it.
> pcibios_free_irq() is an empty weak function in drivers/pci/pci-driver.c.

"pcibios_alloc_irq() is a weak function called to allocate IRQs for
a device in pci_device_probe(); arm64 implements it with
ACPI specific code to enable IRQs for a device.

When a device is removed (pci_device_remove()) the pcibios_free_irq()
counterpart is called.

Current arm64 code does not implement a pcibios_free_irq() function,
and therefore, the weak empty stub is executed, which means that the
IRQ for a device are not properly disabled when a device is removed.

Add an arm64 pcibios_free_irq() to undo the actions carried out in
pcibios_alloc_irq()."

This is a stub commit log. Then you need to describe the bug you
are fixing (if any, or it is just code inspection ?)

> So add pcibios_free_irq() for correspond it. This will be called
> in pci_device_remove().
> 
> ====================
> v2: remove the change in pcibios_alloc_irq(), and modify the commit log.
> ====================

Don't add versioning in the commit log, it does not belong here.

I don't think we should send this to stable kernels straight away,
it is best to make sure we are not triggering any regressions first.

Lorenzo

> Signed-off-by: Yajun Deng <yajun.deng@...ux.dev>
> ---
>  arch/arm64/kernel/pci.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
> index 2276689b5411..6ffd92126f65 100644
> --- a/arch/arm64/kernel/pci.c
> +++ b/arch/arm64/kernel/pci.c
> @@ -29,6 +29,13 @@ int pcibios_alloc_irq(struct pci_dev *dev)
>  
>  	return 0;
>  }
> +
> +void pcibios_free_irq(struct pci_dev *dev)
> +{
> +	if (!acpi_disabled)
> +		acpi_pci_irq_disable(dev);
> +}
> +
>  #endif
>  
>  /*
> -- 
> 2.32.0
>