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

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