[PATCH 1/5] Extend the request_region() infrastructure

[Zoltán Böszörményi <zboszor@xxxxx>]

Add a new IORESOURCE_ALLOCATED flag that is automatically used
when alloc_resource() is used internally in kernel/resource.c
and free_resource() now takes this flag into account.

The core of __request_region() was factored out into a new function
called __request_declared_region() that needs struct resource *
instead of the (start, n, name) triplet.

These changes allow using statically declared struct resource
data coupled with the pre-existing DEFINE_RES_IO_NAMED() static
initializer macro. The new macro exploiting
__request_declared_region() is request_declared_muxed_region()

Signed-off-by: Zoltán Böszörményi <zboszor@xxxxx>
---
 include/linux/ioport.h |  5 +++++
 kernel/resource.c      | 55 +++++++++++++++++++++++++++++++++++---------------
 2 files changed, 44 insertions(+), 16 deletions(-)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index 6230064..a3c4e08 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h
@@ -52,6 +52,7 @@ struct resource {
 #define IORESOURCE_MEM_64	0x00100000
 #define IORESOURCE_WINDOW	0x00200000	/* forwarded by bridge */
 #define IORESOURCE_MUXED	0x00400000	/* Resource is software muxed */
+#define IORESOURCE_ALLOCATED	0x00800000	/* Resource was allocated */
 
 #define IORESOURCE_EXT_TYPE_BITS 0x01000000	/* Resource extended types */
 #define IORESOURCE_SYSRAM	0x01000000	/* System RAM (modifier) */
@@ -216,12 +217,16 @@ static inline bool resource_contains(struct resource *r1, struct resource *r2)
 /* Convenience shorthand with allocation */
 #define request_region(start,n,name)		__request_region(&ioport_resource, (start), (n), (name), 0)
 #define request_muxed_region(start,n,name)	__request_region(&ioport_resource, (start), (n), (name), IORESOURCE_MUXED)
+#define request_declared_muxed_region(res)	__request_declared_region(&ioport_resource, (res), IORESOURCE_MUXED)
 #define __request_mem_region(start,n,name, excl) __request_region(&iomem_resource, (start), (n), (name), excl)
 #define request_mem_region(start,n,name) __request_region(&iomem_resource, (start), (n), (name), 0)
 #define request_mem_region_exclusive(start,n,name) \
 	__request_region(&iomem_resource, (start), (n), (name), IORESOURCE_EXCLUSIVE)
 #define rename_region(region, newname) do { (region)->name = (newname); } while (0)
 
+extern struct resource * __request_declared_region(struct resource *,
+					struct resource *res, int flags);
+
 extern struct resource * __request_region(struct resource *,
 					resource_size_t start,
 					resource_size_t n,
diff --git a/kernel/resource.c b/kernel/resource.c
index 9b5f044..220f695 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -184,6 +184,9 @@ static void free_resource(struct resource *res)
 	if (!res)
 		return;
 
+	if (!(res->flags & IORESOURCE_ALLOCATED))
+		return;
+
 	if (!PageSlab(virt_to_head_page(res))) {
 		spin_lock(&bootmem_resource_lock);
 		res->sibling = bootmem_resource_free;
@@ -210,6 +213,8 @@ static struct resource *alloc_resource(gfp_t flags)
 	else
 		res = kzalloc(sizeof(struct resource), flags);
 
+	res->flags = IORESOURCE_ALLOCATED;
+
 	return res;
 }
 
@@ -1117,26 +1122,15 @@ resource_size_t resource_alignment(struct resource *res)
 static DECLARE_WAIT_QUEUE_HEAD(muxed_resource_wait);
 
 /**
- * __request_region - create a new busy resource region
+ * __request_declared_region - create a new busy resource region
  * @parent: parent resource descriptor
- * @start: resource start address
- * @n: resource region size
- * @name: reserving caller's ID string
+ * @res: child resource descriptor
  * @flags: IO resource flags
  */
-struct resource * __request_region(struct resource *parent,
-				   resource_size_t start, resource_size_t n,
-				   const char *name, int flags)
+struct resource * __request_declared_region(struct resource *parent,
+				   struct resource *res, int flags)
 {
 	DECLARE_WAITQUEUE(wait, current);
-	struct resource *res = alloc_resource(GFP_KERNEL);
-
-	if (!res)
-		return NULL;
-
-	res->name = name;
-	res->start = start;
-	res->end = start + n - 1;
 
 	write_lock(&resource_lock);
 
@@ -1166,13 +1160,42 @@ struct resource * __request_region(struct resource *parent,
 			continue;
 		}
 		/* Uhhuh, that didn't work out.. */
-		free_resource(res);
 		res = NULL;
 		break;
 	}
 	write_unlock(&resource_lock);
 	return res;
 }
+EXPORT_SYMBOL(__request_declared_region);
+
+/**
+ * __request_region - create a new busy resource region
+ * @parent: parent resource descriptor
+ * @start: resource start address
+ * @n: resource region size
+ * @name: reserving caller's ID string
+ * @flags: IO resource flags
+ */
+struct resource * __request_region(struct resource *parent,
+				   resource_size_t start, resource_size_t n,
+				   const char *name, int flags)
+{
+	struct resource *res = alloc_resource(GFP_KERNEL);
+
+	if (!res)
+		return NULL;
+
+	res->name = name;
+	res->start = start;
+	res->end = start + n - 1;
+
+	if (!__request_declared_region(parent, res, flags)) {
+		free_resource(res);
+		res = NULL;
+	}
+
+	return res;
+}
 EXPORT_SYMBOL(__request_region);
 
 /**
-- 
2.9.4

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