Re: [PATCH v4 1/4] PCI: Introduce pcim_alloc_irq_vectors()

Robert Richter
2021-02-19T14:40:53Z

On 18.02.21 23:04:55, Dejin Zheng wrote:
> Introduce pcim_alloc_irq_vectors(), a device-managed version of
> pci_alloc_irq_vectors(). Introducing this function can simplify
> the error handling path in many drivers.
>
> And use pci_free_irq_vectors() to replace some code in pcim_release(),
> they are equivalent, and no functional change. It is more explicit
> that pcim_alloc_irq_vectors() is a device-managed function.
>
> Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Signed-off-by: Dejin Zheng <zhengdejin5@gmail.com>
> ---
> v3 -> v4:
> - No change
> v2 -> v3:
> - Add some commit comments for replace some codes in
> pcim_release() by pci_free_irq_vectors().
> v1 -> v2:
> - Use pci_free_irq_vectors() to replace some code in
> pcim_release().
> - Modify some commit messages.
>
> drivers/pci/pci.c | 33 +++++++++++++++++++++++++++++----
> include/linux/pci.h | 3 +++
> 2 files changed, 32 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index b67c4327d307..db799d089c85 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1969,10 +1969,7 @@ static void pcim_release(struct device *gendev, void *res)
> struct pci_devres *this = res;
> int i;
>
> - if (dev->msi_enabled)
> - pci_disable_msi(dev);
> - if (dev->msix_enabled)
> - pci_disable_msix(dev);
> + pci_free_irq_vectors(dev);
>
> for (i = 0; i < DEVICE_COUNT_RESOURCE; i++)
> if (this->region_mask & (1 << i))
> @@ -2054,6 +2051,34 @@ void pcim_pin_device(struct pci_dev *pdev)
> }
> EXPORT_SYMBOL(pcim_pin_device);
>
> +/**
> + * pcim_alloc_irq_vectors - a device-managed pci_alloc_irq_vectors()
> + * @dev: PCI device to operate on
> + * @min_vecs: minimum number of vectors required (must be >= 1)
> + * @max_vecs: maximum (desired) number of vectors
> + * @flags: flags or quirks for the allocation
> + *
> + * Return the number of vectors allocated, (which might be smaller than
> + * @max_vecs) if successful, or a negative error code on error. If less
> + * than @min_vecs interrupt vectors are available for @dev the function
> + * will fail with -ENOSPC.
> + *
> + * It depends on calling pcim_enable_device() to make IRQ resources
> + * manageable.
> + */
> +int pcim_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
> + unsigned int max_vecs, unsigned int flags)
> +{
> + struct pci_devres *dr;
> +
> + dr = find_pci_dr(dev);
> + if (!dr || !dr->enabled)
> + return -EINVAL;
> +
> + return pci_alloc_irq_vectors(dev, min_vecs, max_vecs, flags);
> +}
> +EXPORT_SYMBOL(pcim_alloc_irq_vectors);

If it is just about having a pcim-* counterpart why not just an inline
function like the one below.

> +
> /*
> * pcibios_add_device - provide arch specific hooks when adding device dev
> * @dev: the PCI device being added
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 86c799c97b77..d75ba85ddfc5 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1818,6 +1818,9 @@ pci_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
> NULL);
> }
>
> +int pcim_alloc_irq_vectors(struct pci_dev *dev, unsigned int min_vecs,
> + unsigned int max_vecs, unsigned int flags);
> +

static inline int pcim_alloc_irq_vectors(struct pci_dev *dev,
unsigned int min_vecs, unsigned int max_vecs, unsigned int flags)
{
if (!pci_is_managed(dev, min_vecs, max_vecs, flags))
return -EINVAL;

return pci_alloc_irq_vectors(dev, min_vecs, max_vecs, flags);
}

All those stub functions with EXPORT_SYMBOLS etc. could be dropped
then.

With some macro magic added a list of functions could easily being
created that are already managed but just need a pcim* counterpart.

-Robert

> /* Include architecture-dependent settings and functions */
>
> #include <asm/pci.h>
> --
> 2.25.0
>