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.
Tested on a machine containing 135 regions. The kernel no longer panicked
with stack overflow.
Also tested with code arbitrarily adding regions with no conflict, embedding
two consecutive conflicts and embedding two non-consecutive conflicts.
Signed-off-by: T Makphaibulchoke <t...@hp.com>
---
Change since v2:
* Initializing both the name and flags fileds of the newly allocated region
request.
Change since v1:
* Fixing __resrve_region_with_split() to ensure a reqion reserve request is
satisfied to the fullest extent, minus any overlapping conflicting regions.
---
kernel/resource.c | 50 ++++++++++++++++++++++++++++++++++++++------------
1 files changed, 38 insertions(+), 12 deletions(-)
diff --git a/kernel/resource.c b/kernel/resource.c
index 34d4588..73f35d4 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -763,6 +763,7 @@ static void __init __reserve_region_with_split(struct
resource *root,
struct resource *parent = root;
struct resource *conflict;
struct resource *res = kzalloc(sizeof(*res), GFP_ATOMIC);
+ struct resource *next_res = NULL;
if (!res)
return;
@@ -772,21 +773,46 @@ static void __init __reserve_region_with_split(struct
resource *root,
res->end = end;
res->flags = IORESOURCE_BUSY;
- conflict = __request_resource(parent, res);
- if (!conflict)
- return;
+ while (1) {
- /* failed, split and try again */
- kfree(res);
+ conflict = __request_resource(parent, res);
+ if (!conflict) {
+ if (!next_res)
+ break;
+ res = next_res;
+ next_res = NULL;
+ continue;
+ }
- /* conflict covered whole area */
- if (conflict->start <= start && conflict->end >= end)
- return;
+ /* conflict covered whole area */
+ if (conflict->start <= res->start &&
+ conflict->end >= res->end) {
+ kfree(res);
+ WARN_ON(next_res);
+ break;
+ }
+
+ /* failed, split and try again */
+ if (conflict->start > res->start) {
+ end = res->end;
+ res->end = conflict->start - 1;
+ if (conflict->end < end) {
+ next_res = kzalloc(sizeof(*next_res),
+ GFP_ATOMIC);
+ if (!next_res) {
+ kfree(res);
+ break;
+ }
+ next_res->name = name;
+ next_res->start = conflict->end + 1;
+ next_res->end = end;
+ next_res->flags = IORESOURCE_BUSY;
+ }
+ } else {
+ res->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
--
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