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, 14 insertions, 16 deletions

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index d1ffca8b34ea..1d30b9f96466 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -145,15 +145,15 @@ static void *unflatten_dt_alloc(void **mem, unsigned long size,
  * @mem: Memory chunk to use for allocating device nodes and properties
  * @p: pointer to node in flat tree
  * @dad: Parent struct device_node
- * @allnextpp: pointer to ->allnext from last allocated device_node
  * @fpsize: Size of the node path up at the current depth.
  */
 static void * unflatten_dt_node(void *blob,
                                 void *mem,
                                 int *poffset,
                                 struct device_node *dad,
-                                struct device_node ***allnextpp,
-                                unsigned long fpsize)
+                                struct device_node **nodepp,
+                                unsigned long fpsize,
+                                bool dryrun)
 {
         const __be32 *p;
         struct device_node *np;
@@ -200,7 +200,7 @@ static void * unflatten_dt_node(void *blob,
 
         np = unflatten_dt_alloc(&mem, sizeof(struct device_node) + allocl,
                                 __alignof__(struct device_node));
-        if (allnextpp) {
+        if (!dryrun) {
                 char *fn;
                 of_node_init(np);
                 np->full_name = fn = ((char *)np) + sizeof(*np);
@@ -222,8 +222,6 @@ static void * unflatten_dt_node(void *blob,
                 memcpy(fn, pathp, l);
 
                 prev_pp = &np->properties;
-                **allnextpp = np;
-                *allnextpp = &np->allnext;
                 if (dad != NULL) {
                         np->parent = dad;
                         /* we temporarily use the next field as `last_child'*/
@@ -254,7 +252,7 @@ static void * unflatten_dt_node(void *blob,
                         has_name = 1;
                 pp = unflatten_dt_alloc(&mem, sizeof(struct property),
                                         __alignof__(struct property));
-                if (allnextpp) {
+                if (!dryrun) {
                         /* We accept flattened tree phandles either in
                          * ePAPR-style "phandle" properties, or the
                          * legacy "linux,phandle" properties.  If both
@@ -296,7 +294,7 @@ static void * unflatten_dt_node(void *blob,
                 sz = (pa - ps) + 1;
                 pp = unflatten_dt_alloc(&mem, sizeof(struct property) + sz,
                                         __alignof__(struct property));
-                if (allnextpp) {
+                if (!dryrun) {
                         pp->name = "name";
                         pp->length = sz;
                         pp->value = pp + 1;
@@ -308,7 +306,7 @@ static void * unflatten_dt_node(void *blob,
                                 (char *)pp->value);
                 }
         }
-        if (allnextpp) {
+        if (!dryrun) {
                 *prev_pp = NULL;
                 np->name = of_get_property(np, "name", NULL);
                 np->type = of_get_property(np, "device_type", NULL);
@@ -324,11 +322,13 @@ static void * unflatten_dt_node(void *blob,
         if (depth < 0)
                 depth = 0;
         while (*poffset > 0 && depth > old_depth)
-                mem = unflatten_dt_node(blob, mem, poffset, np, allnextpp,
-                                        fpsize);
+                mem = unflatten_dt_node(blob, mem, poffset, np, NULL,
+                                        fpsize, dryrun);
 
         if (*poffset < 0 && *poffset != -FDT_ERR_NOTFOUND)
                 pr_err("unflatten: error %d processing FDT\n", *poffset);
+        if (nodepp)
+                *nodepp = np;
 
         return mem;
 }
@@ -352,7 +352,6 @@ static void __unflatten_device_tree(void *blob,
         unsigned long size;
         int start;
         void *mem;
-        struct device_node **allnextp = mynodes;
 
         pr_debug(" -> unflatten_device_tree()\n");
 
@@ -373,7 +372,7 @@ static void __unflatten_device_tree(void *blob,
 
         /* First pass, scan for size */
         start = 0;
-        size = (unsigned long)unflatten_dt_node(blob, NULL, &start, NULL, NULL, 0);
+        size = (unsigned long)unflatten_dt_node(blob, NULL, &start, NULL, NULL, 0, true);
         size = ALIGN(size, 4);
 
         pr_debug("  size is %lx, allocating...\n", size);
@@ -388,11 +387,10 @@ static void __unflatten_device_tree(void *blob,
 
         /* Second pass, do actual unflattening */
         start = 0;
-        unflatten_dt_node(blob, mem, &start, NULL, &allnextp, 0);
+        unflatten_dt_node(blob, mem, &start, NULL, mynodes, 0, false);
         if (be32_to_cpup(mem + size) != 0xdeadbeef)
                 pr_warning("End of tree marker overwritten: %08x\n",
                            be32_to_cpup(mem + size));
-        *allnextp = NULL;
 
         pr_debug(" <- unflatten_device_tree()\n");
 }
@@ -1041,7 +1039,7 @@ bool __init early_init_dt_scan(void *params)
  */
 void __init unflatten_device_tree(void)
 {
-        __unflatten_device_tree(initial_boot_params, &of_allnodes,
+        __unflatten_device_tree(initial_boot_params, &of_root,
                                 early_init_dt_alloc_memory_arch);
 
         /* Get pointer to "/chosen" and "/aliases" nodes for use everywhere */