On Fri, 15 Jan 2010 13:09:31 -0800
Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> On 01/15/2010 11:04 AM, Jesse Barnes wrote:
> > On Tue, 22 Dec 2009 15:02:27 -0800
> > Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> >
> >> when we are clearing leaf bridge resource and try to get big one,
> >> we could shrink the bridge if there is no resource under it.
> >>
> >> let check with old resource size and make sure we are trying to get
> >> big one.
> >>
> >> -v2: keep disable window print out, still could happen on non pci
> >> hotplug system
> >>
> >> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
> >> ---
> >> drivers/pci/setup-bus.c | 14 ++++++++++++--
> >> 1 files changed, 12 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> >> index 9bb4435..d53b42e 100644
> >> --- a/drivers/pci/setup-bus.c
> >> +++ b/drivers/pci/setup-bus.c
> >> @@ -387,7 +387,7 @@ static void pbus_size_io(struct pci_bus *bus,
> >> resource_size_t min_size) {
> >> struct pci_dev *dev;
> >> struct resource *b_res = find_free_bus_resource(bus,
> >> IORESOURCE_IO);
> >> - unsigned long size = 0, size1 = 0;
> >> + unsigned long size = 0, size1 = 0, old_size;
> >>
> >> if (!b_res)
> >> return;
> >> @@ -412,12 +412,17 @@ static void pbus_size_io(struct pci_bus *bus,
> >> resource_size_t min_size) }
> >> if (size < min_size)
> >> size = min_size;
> >> + old_size = resource_size(b_res);
> >> + if (old_size == 1)
> >> + old_size = 0;
> >
> > Do we even need these == 1 checks? If old_size really was 1, it
> > means we had a very small decode range. Might make more sense to
> > do...
>
> when start=0 and end =0, will get old_size = 1
...
if (old_size == 1)
old_size = 0
...
if (size < old_size)
size = old_size
...
If old_size > 1 we'll make sure size doesn't decrease.
If old_size == 1, we'll never touch the changed size because size < 0
will never be true for size (unsigned).
However, if old_size == 1 and we left it at 1, we'd only set size =
old_size if size was 0, which is why I suggested the size check.
What am I missing? When will size shrink? I know it's just
nitpicking, I just want to make sure the code is clear, and that it's
obvious that we're preventing size from decreasing.
--
Jesse Barnes, Intel Open Source Technology Center
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