[PATCH] IO resources: add sticky resource type

[Yinghai Lu]

Ingo suggested to use sticky resource type to record fixed resource.
That way we could check that BAR in the PCI init code and avoid updating
it after request_resource failed.

That way we could remove some tricky code about insert some platform
resources with late_initcall.

Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
 include/linux/ioport.h |    3 ++
 kernel/resource.c      |   58 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+), 0 deletions(-)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 22d2115..db53613 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -48,6 +48,8 @@ struct resource_list {
 #define IORESOURCE_SIZEALIGN	0x00020000	/* size indicates alignment */
 #define IORESOURCE_STARTALIGN	0x00040000	/* start field is alignment */
 
+#define IORESOURCE_STICKY	0x08000000
+
 #define IORESOURCE_DISABLED	0x10000000
 #define IORESOURCE_UNSET	0x20000000
 #define IORESOURCE_AUTO		0x40000000
@@ -109,6 +111,7 @@ extern struct resource iomem_resource;
 extern int request_resource(struct resource *root, struct resource *new);
 extern int release_resource(struct resource *new);
 extern int insert_resource(struct resource *parent, struct resource *new);
+extern struct resource *check_sticky_resource(struct resource *bar_res);
 extern int allocate_resource(struct resource *root, struct resource *new,
 			     resource_size_t size, resource_size_t min,
 			     resource_size_t max, resource_size_t align,
diff --git a/kernel/resource.c b/kernel/resource.c
index f5b518e..957afa7 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -586,6 +586,64 @@ int __check_region(struct resource *parent, resource_size_t start,
 EXPORT_SYMBOL(__check_region);
 
 /**
+ * check_sticky_resource
+ * @bar_res: target resource descriptor
+ *
+ * return res: identical to bar_res, or overlapping it
+ */
+struct resource *check_sticky_resource(struct resource *bar_res)
+{
+	struct resource *parent;
+	struct resource *res;
+
+	if (bar_res->flags | IORESOURCE_MEM)
+		parent = &iomem_resource;
+	else if (bar_res->flags | IORESOURCE_IO)
+		parent = &ioport_resource;
+	else
+		return NULL;
+
+	res = kzalloc(sizeof(*res), GFP_KERNEL);
+	if (res) {
+		res->name = bar_res->name;
+		res->start = bar_res->start;
+		res->end = bar_res->end;
+		res->flags = bar_res->flags | IORESOURCE_BUSY;
+
+		write_lock(&resource_lock);
+
+		for (;;) {
+			struct resource *conflict;
+
+			conflict = __request_resource(parent, res);
+			if (!conflict) {
+				/* not found */
+				break;
+			}
+			if (conflict != parent) {
+				parent = conflict;
+				if (!(conflict->flags & IORESOURCE_STICKY))
+					continue;
+			} else {
+				parent = NULL;
+			}
+
+			kfree(res);
+			res = NULL;
+			break;
+		}
+		write_unlock(&resource_lock);
+	}
+
+	if (res) {
+		release_resource(res);
+		kfree(res);
+	}
+
+	return parent;
+}
+
+/**
  * __release_region - release a previously reserved resource region
  * @parent: parent resource descriptor
  * @start: resource start address

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