Re: [PATCH v6 1/4] PCI: Introduce pci_dev_for_each_resource()

Andy Shevchenko
2023-03-23T14:30:01Z

On Wed, Mar 22, 2023 at 02:28:04PM -0500, Bjorn Helgaas wrote:
> On Mon, Mar 20, 2023 at 03:16:30PM +0200, Andy Shevchenko wrote:

...

> > + pci_dev_for_each_resource_p(dev, r) {
> > /* zap the 2nd function of the winbond chip */
> > - if (dev->resource[i].flags & IORESOURCE_IO
> > - && dev->bus->number == 0 && dev->devfn == 0x81)
> > - dev->resource[i].flags &= ~IORESOURCE_IO;
> > - if (dev->resource[i].start == 0 && dev->resource[i].end) {
> > - dev->resource[i].flags = 0;
> > - dev->resource[i].end = 0;
> > + if (dev->bus->number == 0 && dev->devfn == 0x81 &&
> > + r->flags & IORESOURCE_IO)
>
> This is a nice literal conversion, but it's kind of lame to test
> bus->number and devfn *inside* the loop here, since they can't change
> inside the loop.

Hmm... why are you asking me, even if I may agree on that? It's
in the original code and out of scope of this series.

> > + r->flags &= ~IORESOURCE_IO;
> > + if (r->start == 0 && r->end) {
> > + r->flags = 0;
> > + r->end = 0;
> > }
> > }

...

> > #define pci_resource_len(dev,bar) \
> > ((pci_resource_end((dev), (bar)) == 0) ? 0 : \
> > \
> > - (pci_resource_end((dev), (bar)) - \
> > - pci_resource_start((dev), (bar)) + 1))
> > + resource_size(pci_resource_n((dev), (bar))))
>
> I like this change, but it's unrelated to pci_dev_for_each_resource()
> and unmentioned in the commit log.

And as you rightfully noticed this either. I can split it to a separate one.

...

> > +#define __pci_dev_for_each_resource(dev, res, __i, vartype) \
> > + for (vartype __i = 0; \
> > + res = pci_resource_n(dev, __i), __i < PCI_NUM_RESOURCES; \
> > + __i++)
> > +
> > +#define pci_dev_for_each_resource(dev, res, i) \
> > + __pci_dev_for_each_resource(dev, res, i, )
> > +
> > +#define pci_dev_for_each_resource_p(dev, res) \
> > + __pci_dev_for_each_resource(dev, res, __i, unsigned int)
>
> This series converts many cases to drop the iterator variable ("i"),
> which is fantastic.
>
> Several of the remaining places need the iterator variable only to
> call pci_claim_resource(), which could be converted to take a "struct
> resource *" directly without much trouble.
>
> We don't have to do that pci_claim_resource() conversion now,

Exactly, it's definitely should be separate change.

> but
> since we're converging on the "(dev, res)" style, I think we should
> reverse the names so we have something like:
>
> pci_dev_for_each_resource(dev, res)
> pci_dev_for_each_resource_idx(dev, res, i)

Wouldn't it be more churn, including pci_bus_for_each_resource() correction?

...

> Not sure __pci_dev_for_each_resource() is worthwhile since it only
> avoids repeating that single "for" statement, and passing in "vartype"
> (sometimes empty to implicitly avoid the declaration) is a little
> complicated to read. I think it'd be easier to read like this:

No objections here.

> #define pci_dev_for_each_resource(dev, res) \
> for (unsigned int __i = 0; \
> res = pci_resource_n(dev, __i), __i < PCI_NUM_RESOURCES; \
> __i++)
>
> #define pci_dev_for_each_resource_idx(dev, res, idx) \
> for (idx = 0; \
> res = pci_resource_n(dev, idx), idx < PCI_NUM_RESOURCES; \
> idx++)

--
With Best Regards,
Andy Shevchenko