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of: Drop ->next pointer from struct device_node

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The ->next pointer in struct device_node is a hanger-on from when it was
used to iterate over the whole tree by a particular device_type property
value. Those days are long over, but the fdt unflattening code still
uses it to put nodes in the unflattened tree into the same order as node
in the flat tree. By reworking the unflattening code to reverse the list
after unflattening all the children of a node, the pointer can be
dropped which gives a small amount of memory savings.

Signed-off-by: Grant Likely <grant.likely@linaro.org>
Acked-by: Frank Rowand <frank.rowand@sonymobile.com>
Cc: Gaurav Minocha <gaurav.minocha.os@gmail.com>
This commit is contained in:
Grant Likely 2014-11-28 16:03:33 +00:00
parent 5267720e75
commit 70161ff336
2 changed files with 18 additions and 7 deletions
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24
drivers/of/fdt.c
View file

@ -226,12 +226,8 @@ static void * unflatten_dt_node(void *blob,
prev_pp = &np->properties;
if (dad != NULL) {
np->parent = dad;
/* we temporarily use the next field as `last_child'*/
if (dad->next == NULL)
dad->child = np;
else
dad->next->sibling = np;
dad->next = np;
np->sibling = dad->child;
dad->child = np;
}
}
/* process properties */
@ -329,6 +325,22 @@ static void * unflatten_dt_node(void *blob,
if (*poffset < 0 && *poffset != -FDT_ERR_NOTFOUND)
pr_err("unflatten: error %d processing FDT\n", *poffset);
/*
* Reverse the child list. Some drivers assumes node order matches .dts
* node order
*/
if (!dryrun && np->child) {
struct device_node *child = np->child;
np->child = NULL;
while (child) {
struct device_node *next = child->sibling;
child->sibling = np->child;
np->child = child;
child = next;
}
}
if (nodepp)
*nodepp = np;

1
include/linux/of.h
View file

@ -56,7 +56,6 @@ struct device_node {
struct device_node *parent;
struct device_node *child;
struct device_node *sibling;
struct device_node *next; /* next device of same type */
struct kobject kobj;
unsigned long _flags;
void *data;