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

Arnd Bergmann
2014-07-02T12:38:04Z

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.

Arnd