Re: [PATCH 1/4] PCI: refactor io size calculation code

[Daniel Hellstrom]

Linus Torvalds wrote:

> On Mon, Apr 11, 2011 at 6:18 AM, Daniel Hellstrom <daniel@xxxxxxxxxxx> wrote:
>  
>
> > In commit 13583b16592a ("PCI: refactor io size calculation code"):
> >    
> >
> > > refactor  code  that  calculates  the  io  size in pbus_size_io()
> > > and pbus_mem_io() into separate functions.
> > >
> > > Signed-off-by: Ram Pai <linuxram@xxxxxxxxxx>
> > > ---
> > > drivers/pci/setup-bus.c |   66
> > > ++++++++++++++++++++++++++++++-----------------
> > > 1 files changed, 42 insertions(+), 24 deletions(-)
> > >
> > > diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> > > index 66cb8f4..2121215 100644
> > > --- a/drivers/pci/setup-bus.c
> > > +++ b/drivers/pci/setup-bus.c
> > > @@ -404,6 +404,43 @@ static struct resource *find_free_bus_resource(struct
> > > pci_bus *bus, unsigned lon
> > >       return NULL;
> > > }
> > >
> > >      
> > ...
> >
> >    
> >
> > > +
> > > +static resource_size_t calculate_memsize(resource_size_t size,
> > > +               resource_size_t min_size,
> > > +               resource_size_t size1,
> > > +               resource_size_t old_size,
> > > +               resource_size_t align)
> > > +{
> > > +       if (size < min_size)
> > > +               size = min_size;
> > > +       if (old_size == 1 )
> > > +               old_size = 0;
> > > +       if (size < old_size)
> > > +               size = old_size;
> > > +       size = ALIGN(size + size1, align);
> > > +       return size;
> > > +}
> > > +
> > > /* Sizing the IO windows of the PCI-PCI bridge is trivial,
> > >  since these windows have 4K granularity and the IO ranges
> > >  of non-bridge PCI devices are limited to 256 bytes.
> > >
> > >
> > >      
> > ...
> >
> >    
> >
> > > @@ -516,14 +542,6 @@ static int pbus_size_mem(struct pci_bus *bus,
> > > unsigned long mask,
> > >                       mem64_mask &= r->flags & IORESOURCE_MEM_64;
> > >               }
> > >       }
> > > -       if (size < min_size)
> > > -               size = min_size;
> > > -       old_size = resource_size(b_res);
> > > -       if (old_size == 1)
> > > -               old_size = 0;
> > > -       if (size < old_size)
> > > -               size = old_size;
> > > -
> > >       align = 0;
> > >       min_align = 0;
> > >       for (order = 0; order <= max_order; order++) {
> > > @@ -537,7 +555,7 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned
> > > long mask,
> > >                       min_align = align1 >> 1;
> > >               align += aligns[order];
> > >       }
> > > -       size = ALIGN(size, min_align);
> > > +       size = calculate_memsize(size, min_size, 0, resource_size(b_res),
> > > align);
> > >
> > >      
> > On my SPARC32/LEON4 PCI system I get overlapped areas, double mapped
> > resources. Some BARs on PCIBUS0 are in the same non-prefetchable memory
> > range as the secondary bus PCIBUS1. Changing align to min_align in the above
> > call to calculate_memsize() fixes the problem, and the memory allocation is
> > the same as with 2.6.36.4 kernel.
> >
> > I belive this is just a typo.
> >    
>
> It does seem that way. The original code used 'min_align' and 'align'
> itself is meaningless in that place.
>  
Agree.

> Can you confirm that the patch you talk about as fixing things is the attached?
>
>                  Linus
>  
Yes, the below patch works on the system that triggered the problem 
before. The last min_align was added in a later patch, I missed it 
initially.

Thanks,
Daniel

> ------------------------------------------------------------------------
>
> drivers/pci/setup-bus.c |    4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> index 89d0a6a88df7..ebf51ad1b714 100644
> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -676,10 +676,10 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask,
> 			min_align = align1 >> 1;
> 		align += aligns[order];
> 	}
> -	size0 = calculate_memsize(size, min_size, 0, resource_size(b_res), align);
> +	size0 = calculate_memsize(size, min_size, 0, resource_size(b_res), min_align);
> 	size1 = !add_size ? size :
> 		calculate_memsize(size, min_size+add_size, 0,
> -				resource_size(b_res), align);
> +				resource_size(b_res), min_align);
> 	if (!size0 && !size1) {
> 		if (b_res->start || b_res->end)
> 			dev_info(&bus->self->dev, "disabling bridge window "
>  

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