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Commit 1c388919 authored by Geert Uytterhoeven's avatar Geert Uytterhoeven
Browse files

resources: Add lookup_resource() 



Add a function to find an existing resource by a resource start address.
This allows to implement simple allocators (with a malloc/free-alike API)
on top of the resource system.

Signed-off-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
parent 88efd0bb

include/linux/ioport.h

+1 −0
Original line number Diff line number Diff line
@@ -132,6 +132,7 @@ extern int allocate_resource(struct resource *root, struct resource *new, 
						       resource_size_t,

						       resource_size_t),

			     void *alignf_data);

struct resource *lookup_resource(struct resource *root, resource_size_t start);

int adjust_resource(struct resource *res, resource_size_t start,

		    resource_size_t size);

resource_size_t resource_alignment(struct resource *res);

kernel/resource.c

+21 −0
Original line number Diff line number Diff line
@@ -553,6 +553,27 @@ int allocate_resource(struct resource *root, struct resource *new, 


EXPORT_SYMBOL(allocate_resource);



/**

 * lookup_resource - find an existing resource by a resource start address

 * @root: root resource descriptor

 * @start: resource start address

 *

 * Returns a pointer to the resource if found, NULL otherwise

 */

struct resource *lookup_resource(struct resource *root, resource_size_t start)

{

	struct resource *res;



	read_lock(&resource_lock);

	for (res = root->child; res; res = res->sibling) {

		if (res->start == start)

			break;

	}

	read_unlock(&resource_lock);



	return res;

}



/*

 * Insert a resource into the resource tree. If successful, return NULL,

 * otherwise return the conflicting resource (compare to __request_resource())