We end up traversing subtrees of ranges we are not interested in; let's
optimize this case, skipping such subtrees, cleaning up the function a bit.
Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
---
kernel/resource.c | 25 ++++++++++++++++++++-----
1 file changed, 20 insertions(+), 5 deletions(-)
diff --git a/kernel/resource.c b/kernel/resource.c
index ca9f5198a01f..2999f57da38c 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -73,6 +73,18 @@ static struct resource *next_resource(struct resource *p)
return p->sibling;
}
+static struct resource *next_resource_skip_children(struct resource *p)
+{
+ while (!p->sibling && p->parent)
+ p = p->parent;
+ return p->sibling;
+}
+
+#define for_each_resource(_root, _p, _skip_children) \
+ for ((_p) = (_root)->child; (_p); \
+ (_p) = (_skip_children) ? next_resource_skip_children(_p) : \
+ next_resource(_p))
+
static void *r_next(struct seq_file *m, void *v, loff_t *pos)
{
struct resource *p = v;
@@ -1712,10 +1724,9 @@ static int strict_iomem_checks;
*/
bool iomem_is_exclusive(u64 addr)
{
- struct resource *p = &iomem_resource;
- bool err = false;
- loff_t l;
+ bool skip_children = false, err = false;
int size = PAGE_SIZE;
+ struct resource *p;
if (!strict_iomem_checks)
return false;
@@ -1723,15 +1734,19 @@ bool iomem_is_exclusive(u64 addr)
addr = addr & PAGE_MASK;
read_lock(&resource_lock);
- for (p = p->child; p ; p = r_next(NULL, p, &l)) {
+ for_each_resource(&iomem_resource, p, skip_children) {
/*
* We can probably skip the resources without
* IORESOURCE_IO attribute?
*/
if (p->start >= addr + size)
break;
- if (p->end < addr)
+ if (p->end < addr) {
+ skip_children = true;
continue;
+ }
+ skip_children = false;
+
/*
* A resource is exclusive if IORESOURCE_EXCLUSIVE is set
* or CONFIG_IO_STRICT_DEVMEM is enabled and the
--
2.31.1
