[PATCH v8 3/9] pci: Introduce pci_register_io_range() helper function.

Liviu Dudau
2014-07-02T13:20:42Z

On Wed, Jul 02, 2014 at 01:38:04PM +0100, Arnd Bergmann wrote:
> Some more detailed comments now
>
> On Tuesday 01 July 2014 19:43:28 Liviu Dudau wrote:
> > +/*
> > + * Record the PCI IO range (expressed as CPU physical address + size).
> > + * Return a negative value if an error has occured, zero otherwise
> > + */
> > +int __weak pci_register_io_range(phys_addr_t addr, resource_size_t size)
> > +{
> > +#ifdef PCI_IOBASE
> > + struct io_range *res;
>
> I was confused by the variable naming here: A variable named 'res' is
> normally a 'struct resource'. Maybe better call this 'range'.
>
> > + resource_size_t allocated_size = 0;
> > +
> > + /* check if the range hasn't been previously recorded */
> > + list_for_each_entry(res, &io_range_list, list) {
> > + if (addr >= res->start && addr + size <= res->start + size)
> > + return 0;
> > + allocated_size += res->size;
> > + }
>
> A spin_lock around the list lookup should be sufficient to get around
> the race that Will mentioned.
>
> > + /* range not registed yet, check for available space */
> > + if (allocated_size + size - 1 > IO_SPACE_LIMIT)
> > + return -E2BIG;
>
> It might be better to limit the size to 64K if it doesn't fit at first.

Thanks Arnd for review. Will update and post a new patch soon if I don't
get any other comments.

Best regards,
Liviu

>
>
> Arnd
>
>

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