From f4eb010706b6c96c136c7aaa9079159743f33fa8 Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Fri, 26 Oct 2007 16:54:31 +1000 Subject: [PATCH] [POWERPC] Add of_get_next_parent() Iterating through a device node's parents is simple enough, but dealing with the refcounts properly is a little ugly, and replicating that logic is asking for someone to get it wrong or forget it all together, eg: while (dn != NULL) { /* loop body */ tmp = of_get_parent(dn); of_node_put(dn); dn = tmp; } So add of_get_next_parent(), inspired by of_get_next_child(). The contract is that it returns the parent and drops the reference on the current node, this makes the loop look like: while (dn != NULL) { /* loop body */ dn = of_get_next_parent(dn); } Signed-off-by: Michael Ellerman Acked-by: David S. Miller Signed-off-by: Paul Mackerras --- drivers/of/base.c | 25 +++++++++++++++++++++++++ include/linux/of.h | 1 + 2 files changed, 26 insertions(+) diff --git a/drivers/of/base.c b/drivers/of/base.c index b306fef1ac41..80c9deca5f35 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -137,6 +137,31 @@ struct device_node *of_get_parent(const struct device_node *node) } EXPORT_SYMBOL(of_get_parent); +/** + * of_get_next_parent - Iterate to a node's parent + * @node: Node to get parent of + * + * This is like of_get_parent() except that it drops the + * refcount on the passed node, making it suitable for iterating + * through a node's parents. + * + * Returns a node pointer with refcount incremented, use + * of_node_put() on it when done. + */ +struct device_node *of_get_next_parent(struct device_node *node) +{ + struct device_node *parent; + + if (!node) + return NULL; + + read_lock(&devtree_lock); + parent = of_node_get(node->parent); + of_node_put(node); + read_unlock(&devtree_lock); + return parent; +} + /** * of_get_next_child - Iterate a node childs * @node: parent node diff --git a/include/linux/of.h b/include/linux/of.h index b5f33efcb8e2..6981016dcc25 100644 --- a/include/linux/of.h +++ b/include/linux/of.h @@ -50,6 +50,7 @@ extern struct device_node *of_find_matching_node(struct device_node *from, extern struct device_node *of_find_node_by_path(const char *path); extern struct device_node *of_find_node_by_phandle(phandle handle); extern struct device_node *of_get_parent(const struct device_node *node); +extern struct device_node *of_get_next_parent(struct device_node *node); extern struct device_node *of_get_next_child(const struct device_node *node, struct device_node *prev); #define for_each_child_of_node(parent, child) \ -- 2.20.1