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 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html