It is changed from busn_res only version, because Bjorn found that version
was not holding resource_lock.
Even it may be ok for busn_res not holding resource_lock.
It would be better to have it to be generic and use lock and we would
use it for other resources.

probe_resource() will try to find specified size or more in parent bus.
If can not find current parent resource, and it will try to expand parents
top.
If still can not find that specified on top, it will try to reduce target size
until find one.

It will return 0, if it find any resource that it could use.

Returned resource already register in the tree.

So caller may still need call resource_replace to put real resource in
the tree.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 include/linux/ioport.h |    7 ++
 kernel/resource.c      |  160 ++++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 162 insertions(+), 5 deletions(-)

diff --git a/include/linux/ioport.h b/include/linux/ioport.h
index e885ba2..20a30df 100644
--- a/include/linux/ioport.h
+++ b/include/linux/ioport.h

@@ -156,6 +156,13 @@ extern int allocate_resource(struct resource *root, struct resource *new,

                                                      resource_size_t,
                                                      resource_size_t),
                            void *alignf_data);
+void resource_shrink_parents_top(struct resource *b_res,
+                                long size, struct resource *parent_res);
+struct device;
+int probe_resource(struct resource *b_res,
+                       struct device *dev, struct resource *busn_res,
+                       resource_size_t needed_size, struct resource **p,
+                       int skip_nr, int limit, char *name);

 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);

diff --git a/kernel/resource.c b/kernel/resource.c
index 7640b3a..0c9616f 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c

@@ -521,14 +521,14 @@ out:

 * @alignf: alignment function, optional, called if not NULL
 * @alignf_data: arbitrary data to pass to the @alignf function
 */
-int allocate_resource(struct resource *root, struct resource *new,
+static 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,
                     resource_size_t (*alignf)(void *,
                                               const struct resource *,
                                               resource_size_t,
                                               resource_size_t),
-                     void *alignf_data)
+                     void *alignf_data, bool lock)
 {
       int err;
       struct resource_constraint constraint;

@@ -542,19 +542,33 @@ int allocate_resource(struct resource *root, struct resource *new,

       constraint.alignf = alignf;
       constraint.alignf_data = alignf_data;

-       if ( new->parent ) {
+       if (new->parent && lock) {
               /* resource is already allocated, try reallocating with
                  the new constraints */
               return reallocate_resource(root, new, size, &constraint);
       }

-       write_lock(&resource_lock);
+       if (lock)
+               write_lock(&resource_lock);
       err = find_resource(root, new, size, &constraint);
       if (err >= 0 && __request_resource(root, new))
               err = -EBUSY;
-       write_unlock(&resource_lock);
+       if (lock)
+               write_unlock(&resource_lock);
       return err;
 }
+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,
+                     resource_size_t (*alignf)(void *,
+                                               const struct resource *,
+                                               resource_size_t,
+                                               resource_size_t),
+                     void *alignf_data)
+{
+       return __allocate_resource(root, new, size, min, max, align,
+                                  alignf, alignf_data, true);
+}

 EXPORT_SYMBOL(allocate_resource);

@@ -962,6 +976,142 @@ void __release_region(struct resource *parent, resource_size_t start,

 }
 EXPORT_SYMBOL(__release_region);

+static void __resource_update_parents_top(struct resource *b_res,
+                long size, struct resource *parent_res)
+{
+       struct resource *res = b_res;
+
+       if (!size)
+               return;
+
+       while (res) {
+               if (res == parent_res)
+                       break;
+               res->end += size;
+               res = res->parent;
+       }
+}
+
+static void __resource_extend_parents_top(struct resource *b_res,
+                long size, struct resource *parent_res)
+{
+       __resource_update_parents_top(b_res, size, parent_res);
+}
+
+void resource_shrink_parents_top(struct resource *b_res,
+                long size, struct resource *parent_res)
+{
+       write_lock(&resource_lock);
+       __resource_update_parents_top(b_res, -size, parent_res);
+       write_unlock(&resource_lock);
+}
+
+static resource_size_t __find_res_top_free_size(struct resource *res)
+{
+       resource_size_t n_size;
+       struct resource tmp_res;
+
+       /*
+        *   find out number below res->end, that we can use at first
+        *      res->start can not be used.
+        */
+       n_size = resource_size(res) - 1;
+       memset(&tmp_res, 0, sizeof(struct resource));
+       while (n_size > 0) {
+               int ret;
+
+               ret = __allocate_resource(res, &tmp_res, n_size,
+                       res->end - n_size + 1, res->end,
+                       1, NULL, NULL, false);
+               if (ret == 0) {
+                       __release_resource(&tmp_res);
+                       break;
+               }
+               n_size--;
+       }
+
+       return n_size;
+}
+
+int probe_resource(struct resource *b_res,
+                        struct device *dev, struct resource *busn_res,
+                        resource_size_t needed_size, struct resource **p,
+                        int skip_nr, int limit, char *name)
+{
+       int ret = -ENOMEM;
+       resource_size_t n_size;
+       struct resource *parent_res = NULL;
+       resource_size_t tmp = b_res->end + 1;
+
+again:
+       /*
+        * find biggest range in b_res that we can use in the middle
+        *  and we can not use some spots from start of b_res.
+        */
+       n_size = resource_size(b_res);
+       if (n_size > skip_nr)
+               n_size -= skip_nr;
+       else
+               n_size = 0;
+
+       memset(busn_res, 0, sizeof(struct resource));
+       dev_printk(KERN_DEBUG, dev, "find free %s in res: %pR\n", name, b_res);
+       while (n_size >= needed_size) {
+               ret = allocate_resource(b_res, busn_res, n_size,
+                               b_res->start + skip_nr, b_res->end,
+                               1, NULL, NULL);
+               if (!ret)
+                       return ret;
+               n_size--;
+       }
+
+       /* try extend the top of parent bus, find free under top at first */
+       write_lock(&resource_lock);
+       n_size = __find_res_top_free_size(b_res);
+       dev_printk(KERN_DEBUG, dev, "found free %s %ld in res: %pR top\n",
+                       name, (unsigned long)n_size, b_res);
+
+       /* can not extend cross local boundary */
+       if ((limit - b_res->end) < (needed_size - n_size))
+               goto reduce_needed_size;
+
+       /* find extended range */
+       memset(busn_res, 0, sizeof(struct resource));
+       parent_res = b_res;
+       while (parent_res) {
+               ret = __allocate_resource(parent_res, busn_res,
+                        needed_size - n_size,
+                        tmp, tmp + needed_size - n_size - 1,
+                        1, NULL, NULL, false);
+               if (!ret) {
+                       /* save parent_res, we need it as stopper later */
+                       *p = parent_res;
+
+                       /* prepare busn_res for return */
+                       __release_resource(busn_res);
+                       busn_res->start -= n_size;
+
+                       /* extend parent bus top*/
+                       __resource_extend_parents_top(b_res,
+                                        needed_size - n_size, parent_res);
+                       __request_resource(b_res, busn_res);
+
+                       write_unlock(&resource_lock);
+                       return ret;
+               }
+               parent_res = parent_res->parent;
+       }
+
+reduce_needed_size:
+       write_unlock(&resource_lock);
+       /* ret must not be 0 here */
+       needed_size--;
+       if (needed_size)
+               goto again;
+
+       return ret;
+}
+
 /*
 * Managed region resource
 */
--
1.7.7