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Date: Mon, 6 Oct 2014 08:56:28 -0500
From: Rob Herring <robh@...nel.org>
To: Grant Likely <grant.likely@...aro.org>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
Gaurav Minocha <gaurav.minocha.os@...il.com>
Subject: Re: [PATCH] of: Eliminate of_allnodes list
On Mon, Oct 6, 2014 at 3:59 AM, Grant Likely <grant.likely@...aro.org> wrote:
> 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@...aro.org>
> Cc: Rob Herring <robh@...nel.org>
> Cc: Gaurav Minocha <gaurav.minocha.os@...il.com>
> ---
>
> This applies against my current devicetree/next branch on git.secretlab.ca/git/linux
>
> I'm not going to try and merge this in v3.18. It's too risky a patch and
> I only just wrote it. I'll try to get it in for v3.19.
Looks good. A few minor things below.
[...]
> diff --git a/drivers/mfd/vexpress-sysreg.c b/drivers/mfd/vexpress-sysreg.c
> index 9e21e4fc9599..8f43ab8fd2d6 100644
> --- a/drivers/mfd/vexpress-sysreg.c
> +++ b/drivers/mfd/vexpress-sysreg.c
> @@ -223,7 +223,7 @@ static int vexpress_sysreg_probe(struct platform_device *pdev)
> vexpress_config_set_master(vexpress_sysreg_get_master());
>
> /* Confirm board type against DT property, if available */
> - if (of_property_read_u32(of_allnodes, "arm,hbi", &dt_hbi) == 0) {
> + if (of_property_read_u32(of_root, "arm,hbi", &dt_hbi) == 0) {
Given this and selftests are the only users in the whole tree, perhaps
this should just use of_find_node_by_path("/") rather than expose this
global.
> u32 id = vexpress_get_procid(VEXPRESS_SITE_MASTER);
> u32 hbi = (id >> SYS_PROCIDx_HBI_SHIFT) & SYS_HBI_MASK;
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 2305dc0382bc..b86beff7b167 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 {
Your braces are inconsistent.
> + /* 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;
[...]
> diff --git a/drivers/of/selftest.c b/drivers/of/selftest.c
> index 4fed34bff5cf..9cc2363a9077 100644
> --- a/drivers/of/selftest.c
> +++ b/drivers/of/selftest.c
> @@ -148,7 +148,7 @@ static void __init of_selftest_dynamic(void)
>
> static int __init of_selftest_check_node_linkage(struct device_node *np)
> {
> - struct device_node *child, *allnext_index = np;
> + struct device_node *child;
> int count = 0, rc;
>
> for_each_child_of_node(np, child) {
> @@ -158,14 +158,6 @@ static int __init of_selftest_check_node_linkage(struct device_node *np)
> return -EINVAL;
> }
>
> - while (allnext_index && allnext_index != child)
> - allnext_index = allnext_index->allnext;
> - if (allnext_index != child) {
> - pr_err("Node %s is ordered differently in sibling and allnode lists\n",
> - child->name);
> - return -EINVAL;
> - }
> -
> rc = of_selftest_check_node_linkage(child);
> if (rc < 0)
> return rc;
> @@ -180,12 +172,12 @@ static void __init of_selftest_check_tree_linkage(void)
> struct device_node *np;
> int allnode_count = 0, child_count;
>
> - if (!of_allnodes)
> + if (!of_root)
This could be !of_have_populated_dt() instead.
> return;
>
> for_each_of_allnodes(np)
> allnode_count++;
> - child_count = of_selftest_check_node_linkage(of_allnodes);
> + child_count = of_selftest_check_node_linkage(of_root);
>
> selftest(child_count > 0, "Device node data structure is corrupted\n");
> selftest(child_count == allnode_count, "allnodes list size (%i) doesn't match"
> @@ -722,33 +714,29 @@ static void update_node_properties(struct device_node *np,
> */
> static int attach_node_and_children(struct device_node *np)
> {
> - struct device_node *next, *root = np, *dup;
> + struct device_node *next, *dup, *child;
>
> - /* skip root node */
> - np = np->child;
> - /* storing a copy in temporary node */
> - dup = np;
> + dup = of_find_node_by_path(np->full_name);
> + if (dup) {
> + update_node_properties(np, dup);
> + return 0;
> + }
>
> - while (dup) {
> + /* Children of the root need to be remembered for removal */
> + if (np->parent == of_root) {
> if (WARN_ON(last_node_index >= NO_OF_NODES))
> return -EINVAL;
> - nodes[last_node_index++] = dup;
> - dup = dup->sibling;
> + nodes[last_node_index++] = np;
> }
> - dup = NULL;
>
> - while (np) {
> - next = np->allnext;
> - dup = of_find_node_by_path(np->full_name);
> - if (dup)
> - update_node_properties(np, dup);
> - else {
> - np->child = NULL;
> - if (np->parent == root)
> - np->parent = of_allnodes;
> - of_attach_node(np);
> - }
> - np = next;
> + child = np->child;
> + np->child = NULL;
> + np->sibling = NULL;
> + of_attach_node(np);
> + while (child) {
> + next = child->sibling;
> + attach_node_and_children(child);
> + child = next;
> }
>
> return 0;
> @@ -793,10 +781,10 @@ static int __init selftest_data_add(void)
> return -EINVAL;
> }
>
> - if (!of_allnodes) {
> + if (!of_root) {
This could be !of_have_populated_dt() instead.
> /* enabling flag for removing nodes */
> selftest_live_tree = true;
> - of_allnodes = selftest_data_node;
> + of_root = selftest_data_node;
>
> for_each_of_allnodes(np)
> __of_attach_node_sysfs(np);
> @@ -806,7 +794,14 @@ static int __init selftest_data_add(void)
> }
>
> /* attach the sub-tree to live tree */
> - return attach_node_and_children(selftest_data_node);
> + np = selftest_data_node->child;
> + while (np) {
> + struct device_node *next = np->sibling;
> + np->parent = of_root;
> + attach_node_and_children(np);
> + np = next;
> + }
You have the same loop iteration a couple of times like this. You
could define an iterator macro.
Rob
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