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

[Liviu Dudau]

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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