Re: [patch RFC 13/38] PCI: MSI: Rework pci_msi_domain_calc_hwirq()

[Bjorn Helgaas <helgaas@xxxxxxxxxx>]

On Fri, Aug 21, 2020 at 02:24:37AM +0200, Thomas Gleixner wrote:
> Retrieve the PCI device from the msi descriptor instead of doing so at the
> call sites.

I'd like it *better* with "PCI/MSI: " in the subject (to match history
and other patches in this series) and "MSI" here in the commit log,
but nice cleanup and:

Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

Minor comments below.

> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: linux-pci@xxxxxxxxxxxxxxx
> ---
>  arch/x86/kernel/apic/msi.c |    2 +-
>  drivers/pci/msi.c          |   13 ++++++-------
>  include/linux/msi.h        |    3 +--
>  3 files changed, 8 insertions(+), 10 deletions(-)
> 
> --- a/arch/x86/kernel/apic/msi.c
> +++ b/arch/x86/kernel/apic/msi.c
> @@ -232,7 +232,7 @@ EXPORT_SYMBOL_GPL(pci_msi_prepare);
>  
>  void pci_msi_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc)
>  {
> -     arg->msi_hwirq = pci_msi_domain_calc_hwirq(arg->msi_dev, desc);
> +     arg->msi_hwirq = pci_msi_domain_calc_hwirq(desc);

I guess it's safe to assume that "arg->msi_dev ==
msi_desc_to_pci_dev(desc)"?  I didn't try to verify that.

>  }
>  EXPORT_SYMBOL_GPL(pci_msi_set_desc);
>  
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -1346,17 +1346,17 @@ void pci_msi_domain_write_msg(struct irq
>  
>  /**
>   * pci_msi_domain_calc_hwirq - Generate a unique ID for an MSI source
> - * @dev:     Pointer to the PCI device
>   * @desc:    Pointer to the MSI descriptor
>   *
>   * The ID number is only used within the irqdomain.
>   */
> -irq_hw_number_t pci_msi_domain_calc_hwirq(struct pci_dev *dev,
> -                                       struct msi_desc *desc)
> +irq_hw_number_t pci_msi_domain_calc_hwirq(struct msi_desc *desc)
>  {
> +     struct pci_dev *pdev = msi_desc_to_pci_dev(desc);

If you named this "struct pci_dev *dev" (not "pdev"), the diff would
be a little smaller and it would match other usage in the file.

>       return (irq_hw_number_t)desc->msi_attrib.entry_nr |
> -             pci_dev_id(dev) << 11 |
> -             (pci_domain_nr(dev->bus) & 0xFFFFFFFF) << 27;
> +             pci_dev_id(pdev) << 11 |
> +             (pci_domain_nr(pdev->bus) & 0xFFFFFFFF) << 27;
>  }
>  
>  static inline bool pci_msi_desc_is_multi_msi(struct msi_desc *desc)
> @@ -1406,8 +1406,7 @@ static void pci_msi_domain_set_desc(msi_
>                                   struct msi_desc *desc)
>  {
>       arg->desc = desc;
> -     arg->hwirq = pci_msi_domain_calc_hwirq(msi_desc_to_pci_dev(desc),
> -                                            desc);
> +     arg->hwirq = pci_msi_domain_calc_hwirq(desc);
>  }
>  #else
>  #define pci_msi_domain_set_desc              NULL
> --- a/include/linux/msi.h
> +++ b/include/linux/msi.h
> @@ -369,8 +369,7 @@ void pci_msi_domain_write_msg(struct irq
>  struct irq_domain *pci_msi_create_irq_domain(struct fwnode_handle *fwnode,
>                                            struct msi_domain_info *info,
>                                            struct irq_domain *parent);
> -irq_hw_number_t pci_msi_domain_calc_hwirq(struct pci_dev *dev,
> -                                       struct msi_desc *desc);
> +irq_hw_number_t pci_msi_domain_calc_hwirq(struct msi_desc *desc);
>  int pci_msi_domain_check_cap(struct irq_domain *domain,
>                            struct msi_domain_info *info, struct device *dev);
>  u32 pci_msi_domain_get_msi_rid(struct irq_domain *domain, struct pci_dev 
> *pdev);
>