Commit 3ad674d6 authored Oct 09, 2013 by Alexey Neyman Committed by Bjorn Helgaas Oct 10, 2013

x86/PCI: Coalesce multiple overlapping host bridge windows

Previously we coalesced windows by expanding the first overlapping one and
making the second invalid.  But we never look at the expanded first window
again, so we fail to notice other windows that overlap it.  For example, we
coalesced these:

  [io  0x0000-0x03af] // #0
  [io  0x03e0-0x0cf7] // #1
  [io  0x0000-0xdfff] // #2

into these, which still overlap:

  [io  0x0000-0xdfff] // #0
  [io  0x03e0-0x0cf7] // #1

The fix is to expand the *second* overlapping resource and ignore the
first, so we get this instead with no overlaps:

  [io  0x0000-0xdfff] // #2

[bhelgaas: changelog]
Reference: https://bugzilla.kernel.org/show_bug.cgi?id=62511


Signed-off-by: Alexey Neyman <stilor@att.net>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

parent 6b49ee49

arch/x86/pci/acpi.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -354,12 +354,12 @@ static void coalesce_windows(struct pci_root_info *info, unsigned long type)
		* the kernel resource tree doesn't allow overlaps.
		*/
		if (resource_overlaps(res1, res2)) {
		res1->start = min(res1->start, res2->start);
		res1->end = max(res1->end, res2->end);
		res2->start = min(res1->start, res2->start);
		res2->end = max(res1->end, res2->end);
		dev_info(&info->bridge->dev,
		"host bridge window expanded to %pR; %pR ignored\n",
		res1, res2);
		res2->flags = 0;
		res2, res1);
		res1->flags = 0;
		}
		}
		}

Admin message