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diff --git a/kernel/resource.c b/kernel/resource.c
index ace2269..1a2a40e 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -358,6 +358,20 @@ int __weak page_is_ram(unsigned long pfn)
}
/*
+ * Find the resource before "child" in the sibling list of "root" children.
+ */
+static struct resource *find_sibling_prev(struct resource *root, struct resource *child)
+{
+ struct resource *this;
+
+ for (this = root->child; this; this = this->sibling)
+ if (this->sibling == child)
+ return this;
+
+ return NULL;
+}
+
+/*
* Find empty slot in the resource tree given range and alignment.
*/
static int find_resource(struct resource *root, struct resource *new,
@@ -369,24 +383,18 @@ static int find_resource(struct resource *root, struct resource *new,
resource_size_t),
void *alignf_data)
{
- struct resource *this = root->child;
+ struct resource *this;
struct resource tmp = *new;
resource_size_t start;
- tmp.start = root->start;
- /*
- * Skip past an allocated resource that starts at 0, since the assignment
- * of this->start - 1 to tmp->end below would cause an underflow.
- */
- if (this && this->start == 0) {
- tmp.start = this->end + 1;
- this = this->sibling;
- }
- for(;;) {
+ tmp.end = root->end;
+
+ this = find_sibling_prev(root, NULL);
+ for (;;) {
if (this)
- tmp.end = this->start - 1;
+ tmp.start = this->end + 1;
else
- tmp.end = root->end;
+ tmp.start = root->start;
if (tmp.start < min)
tmp.start = min;
if (tmp.end > max)
@@ -404,10 +412,10 @@ static int find_resource(struct resource *root, struct resource *new,
new->end = tmp.start + size - 1;
return 0;
}
- if (!this)
+ if (!this || this->start == root->start)
break;
- tmp.start = this->end + 1;
- this = this->sibling;
+ tmp.end = this->start - 1;
+ this = find_sibling_prev(root, this);
}
return -EBUSY;
}
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