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

Dejin Zheng
2021-02-19T16:48:05Z

On Fri, Feb 19, 2021 at 03:40:05PM +0100, Robert Richter wrote:
> 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.
>
Robert and Andy,

First of all, thank you very much for your suggestions and help.
I think this is not just a pcim-* counterpart, I may not explain this
place clearly. In addition to calling pci_alloc_irq_vectors(), the
pcim_alloc_irq_vectors() function also checks whether the pci device is
enabled and whether the pci device resource has been managed. If any one
is wrong, it will return failure. Therefore, I think it should be used
as a function. For novices, maybe I understand it incorrectly, so I look
forward to your suggestions.

> > + dr = find_pci_dr(dev);
static struct pci_devres *find_pci_dr(struct pci_dev *pdev)
{
if (pci_is_managed(pdev))
return devres_find(&pdev->dev, pcim_release, NULL, NULL);
return NULL;
}
here checks whether the pci device resource has been managed.

> > + if (!dr || !dr->enabled)
here checks whether the pci device is enabled.

int pcim_enable_device(struct pci_dev *pdev)
{
struct pci_devres *dr;
int rc;

dr = get_pci_dr(pdev);
if (unlikely(!dr))
return -ENOMEM;
if (dr->enabled)
return 0;

rc = pci_enable_device(pdev);
if (!rc) {
pdev->is_managed = 1;
dr->enabled = 1;
}
return rc;
}

BR,
Dejin

> > +
> > /*
> > * 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
> >