of: Eliminate of_allnodes list

The device tree structure is composed of two lists; the 'allnodes' list
which is a singly linked list containing every node in the tree, and the
child->parent structure where each parent node has a singly linked list
of children. All of the data in the allnodes list can be easily
reproduced with the parent-child lists, so of_allnodes is actually
unnecessary. Remove it entirely which saves a bit of memory and
simplifies the data structure quite a lot.

Signed-off-by: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Gaurav Minocha <gaurav.minocha.os@gmail.com>
Cc: Pantelis Antoniou <pantelis@pantelis.antoniou@konsulko.com>

1 files changed, 31 insertions, 22 deletions

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 3823edf2d012..1f61a908a767 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -32,8 +32,8 @@
 
 LIST_HEAD(aliases_lookup);
 
-struct device_node *of_allnodes;
-EXPORT_SYMBOL(of_allnodes);
+struct device_node *of_root;
+EXPORT_SYMBOL(of_root);
 struct device_node *of_chosen;
 struct device_node *of_aliases;
 struct device_node *of_stdout;
@@ -48,7 +48,7 @@ struct kset *of_kset;
  */
 DEFINE_MUTEX(of_mutex);
 
-/* use when traversing tree through the allnext, child, sibling,
+/* use when traversing tree through the child, sibling,
  * or parent members of struct device_node.
  */
 DEFINE_RAW_SPINLOCK(devtree_lock);
@@ -204,7 +204,7 @@ static int __init of_init(void)
         mutex_unlock(&of_mutex);
 
         /* Symlink in /proc as required by userspace ABI */
-        if (of_allnodes)
+        if (of_root)
                 proc_symlink("device-tree", NULL, "/sys/firmware/devicetree/base");
 
         return 0;
@@ -245,6 +245,23 @@ struct property *of_find_property(const struct device_node *np,
 }
 EXPORT_SYMBOL(of_find_property);
 
+struct device_node *__of_find_all_nodes(struct device_node *prev)
+{
+        struct device_node *np;
+        if (!prev) {
+                np = of_root;
+        } else if (prev->child) {
+                np = prev->child;
+        } else {
+                /* Walk back up looking for a sibling, or the end of the structure */
+                np = prev;
+                while (np->parent && !np->sibling)
+                        np = np->parent;
+                np = np->sibling; /* Might be null at the end of the tree */
+        }
+        return np;
+}
+
 /**
  * of_find_all_nodes - Get next node in global list
  * @prev:       Previous node or NULL to start iteration
@@ -259,10 +276,8 @@ struct device_node *of_find_all_nodes(struct device_node *prev)
         unsigned long flags;
 
         raw_spin_lock_irqsave(&devtree_lock, flags);
-        np = prev ? prev->allnext : of_allnodes;
-        for (; np != NULL; np = np->allnext)
-                if (of_node_get(np))
-                        break;
+        np = __of_find_all_nodes(prev);
+        of_node_get(np);
         of_node_put(prev);
         raw_spin_unlock_irqrestore(&devtree_lock, flags);
         return np;
@@ -736,7 +751,7 @@ struct device_node *of_find_node_by_path(const char *path)
         unsigned long flags;
 
         if (strcmp(path, "/") == 0)
-                return of_node_get(of_allnodes);
+                return of_node_get(of_root);
 
         /* The path could begin with an alias */
         if (*path != '/') {
@@ -761,7 +776,7 @@ struct device_node *of_find_node_by_path(const char *path)
         /* Step down the tree matching path components */
         raw_spin_lock_irqsave(&devtree_lock, flags);
         if (!np)
-                np = of_node_get(of_allnodes);
+                np = of_node_get(of_root);
         while (np && *path == '/') {
                 path++; /* Increment past '/' delimiter */
                 np = __of_find_node_by_path(np, path);
@@ -790,8 +805,7 @@ struct device_node *of_find_node_by_name(struct device_node *from,
         unsigned long flags;
 
         raw_spin_lock_irqsave(&devtree_lock, flags);
-        np = from ? from->allnext : of_allnodes;
-        for (; np; np = np->allnext)
+        for_each_of_allnodes_from(from, np)
                 if (np->name && (of_node_cmp(np->name, name) == 0)
                     && of_node_get(np))
                         break;
@@ -820,8 +834,7 @@ struct device_node *of_find_node_by_type(struct device_node *from,
         unsigned long flags;
 
         raw_spin_lock_irqsave(&devtree_lock, flags);
-        np = from ? from->allnext : of_allnodes;
-        for (; np; np = np->allnext)
+        for_each_of_allnodes_from(from, np)
                 if (np->type && (of_node_cmp(np->type, type) == 0)
                     && of_node_get(np))
                         break;
@@ -852,12 +865,10 @@ struct device_node *of_find_compatible_node(struct device_node *from,
         unsigned long flags;
 
         raw_spin_lock_irqsave(&devtree_lock, flags);
-        np = from ? from->allnext : of_allnodes;
-        for (; np; np = np->allnext) {
+        for_each_of_allnodes_from(from, np)
                 if (__of_device_is_compatible(np, compatible, type, NULL) &&
                     of_node_get(np))
                         break;
-        }
         of_node_put(from);
         raw_spin_unlock_irqrestore(&devtree_lock, flags);
         return np;
@@ -884,8 +895,7 @@ struct device_node *of_find_node_with_property(struct device_node *from,
         unsigned long flags;
 
         raw_spin_lock_irqsave(&devtree_lock, flags);
-        np = from ? from->allnext : of_allnodes;
-        for (; np; np = np->allnext) {
+        for_each_of_allnodes_from(from, np) {
                 for (pp = np->properties; pp; pp = pp->next) {
                         if (of_prop_cmp(pp->name, prop_name) == 0) {
                                 of_node_get(np);
@@ -967,8 +977,7 @@ struct device_node *of_find_matching_node_and_match(struct device_node *from,
                 *match = NULL;
 
         raw_spin_lock_irqsave(&devtree_lock, flags);
-        np = from ? from->allnext : of_allnodes;
-        for (; np; np = np->allnext) {
+        for_each_of_allnodes_from(from, np) {
                 m = __of_match_node(matches, np);
                 if (m && of_node_get(np)) {
                         if (match)
@@ -1025,7 +1034,7 @@ struct device_node *of_find_node_by_phandle(phandle handle)
                 return NULL;
 
         raw_spin_lock_irqsave(&devtree_lock, flags);
-        for (np = of_allnodes; np; np = np->allnext)
+        for_each_of_allnodes(np)
                 if (np->phandle == handle)
                         break;
         of_node_get(np);