[PATCH] kernel/resource.c: fix stack overflow in __reserve_region_with_split

T Makphaibulchoke
2012-08-28T00:47:58Z

Using recurvise call to try adding a non-conflicting region in the function
__reserve_region_with_split() could result in a stack overflow in the case
that the recursive calls are too deep. Convert the recursive calls to
an iterative loop to avoid the problem.

Signed-off-by: T Makphaibulchoke <tmac@hp.com>
---
kernel/resource.c | 32 ++++++++++++++++++--------------
1 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/kernel/resource.c b/kernel/resource.c
index 34d4588..d6e9f9c 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -768,25 +768,29 @@ static void __init __reserve_region_with_split(struct resource *root,
return;

res->name = name;
- res->start = start;
- res->end = end;
res->flags = IORESOURCE_BUSY;

- conflict = __request_resource(parent, res);
- if (!conflict)
- return;
+ while (1) {
+ res->start = start;
+ res->end = end;

- /* failed, split and try again */
- kfree(res);
+ conflict = __request_resource(parent, res);
+ if (!conflict)
+ break;

- /* conflict covered whole area */
- if (conflict->start <= start && conflict->end >= end)
- return;
+ /* conflict covered whole area */
+ if (conflict->start <= start && conflict->end >= end) {
+ kfree(res);
+ break;
+ }
+
+ /* failed, split and try again */
+ if (conflict->start > start)
+ end = conflict->start - 1;
+ if (conflict->end < end)
+ start = conflict->end + 1;
+ }

- if (conflict->start > start)
- __reserve_region_with_split(root, start, conflict->start-1, name);
- if (conflict->end < end)
- __reserve_region_with_split(root, conflict->end+1, end, name);
}

void __init reserve_region_with_split(struct resource *root,
--
1.7.1