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

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Message-ID: <20210922162201.GA24429@lpieralisi>
Date:   Wed, 22 Sep 2021 17:22:01 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     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 Wed, Sep 22, 2021 at 02:49:13AM +0000, yajun.deng@...ux.dev wrote:
> September 21, 2021 11:47 PM, "Lorenzo Pieralisi" <lorenzo.pieralisi@....com> wrote:
> 
> > 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 ?)
> > 
> It is just code inspection.

Before merging it it must be tested, which would prove it is needed.

Lorenzo

> >> 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