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authorRam Pai <linuxram@us.ibm.com>2011-09-22 15:48:58 +0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-09-29 20:04:34 -0700
commit47ea91b4052d9e94b9dca5d7a3d947fbebd07ba9 (patch)
tree079ecdd16d4e73e783851cca3ba8bda9cbd8fa8d
parent92bb062fe36132a04c6dc8b3c51c945730b05224 (diff)
Resource: fix wrong resource window calculation
__find_resource() incorrectly returns a resource window which overlaps an existing allocated window. This happens when the parent's resource-window spans 0x00000000 to 0xffffffff and is entirely allocated to all its children resource-windows. __find_resource() looks for gaps in resource allocation among the children resource windows. When it encounters the last child window it blindly tries the range next to one allocated to the last child. Since the last child's window ends at 0xffffffff the calculation overflows, leading the algorithm to believe that any window in the range 0x0000000 to 0xfffffff is available for allocation. This leads to a conflicting window allocation. Michal Ludvig reported this issue seen on his platform. The following patch fixes the problem and has been verified by Michal. I believe this bug has been there for ages. It got exposed by git commit 2bbc6942273b ("PCI : ability to relocate assigned pci-resources") Signed-off-by: Ram Pai <linuxram@us.ibm.com> Tested-by: Michal Ludvig <mludvig@logix.net.nz> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--kernel/resource.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/kernel/resource.c b/kernel/resource.c
index 3b3cedc52592..c8dc249da5ce 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -419,6 +419,9 @@ static int __find_resource(struct resource *root, struct resource *old,
else
tmp.end = root->end;
+ if (tmp.end < tmp.start)
+ goto next;
+
resource_clip(&tmp, constraint->min, constraint->max);
arch_remove_reservations(&tmp);
@@ -436,8 +439,10 @@ static int __find_resource(struct resource *root, struct resource *old,
return 0;
}
}
- if (!this)
+
+next: if (!this || this->end == root->end)
break;
+
if (this != old)
tmp.start = this->end + 1;
this = this->sibling;