[05/16] of: overlay: use prop add changeset entry for property in new nodes

Message ID 1538712767-30394-6-git-send-email-frowand.list@gmail.com
State Superseded
Headers show
Series
  • of: overlay: validation checks, subsequent fixes
Related show

Commit Message

Frank Rowand Oct. 5, 2018, 4:12 a.m.
From: Frank Rowand <frank.rowand@sony.com>

The changeset entry 'update property' was used for new properties in
an overlay instead of 'add property'.

The decision of whether to use 'update property' was based on whether
the property already exists in the subtree where the node is being
spliced into.  At the top level of creating a changeset describing the
overlay, the target node is in the live devicetree, so checking whether
the property exists in the target node returns the correct result.
As soon as the changeset creation algorithm recurses into a new node,
the target is no longer in the live devicetree, but is instead in the
detached overlay tree, thus all properties are incorrectly found to
already exist in the target.

This fix will expose another devicetree bug that will be fixed
in the following patch in the series.

When this patch is applied the errors reported by the devictree
unittest will change, and the unittest results will change from:

   ### dt-test ### end of unittest - 210 passed, 0 failed

to

   ### dt-test ### end of unittest - 203 passed, 7 failed

Signed-off-by: Frank Rowand <frank.rowand@sony.com>
---
 drivers/of/overlay.c | 112 ++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 74 insertions(+), 38 deletions(-)

Comments

Alan Tull Oct. 9, 2018, 8:28 p.m. | #1
On Thu, Oct 4, 2018 at 11:14 PM <frowand.list@gmail.com> wrote:
>
> From: Frank Rowand <frank.rowand@sony.com>
>

Hi Frank,

> The changeset entry 'update property' was used for new properties in
> an overlay instead of 'add property'.
>
> The decision of whether to use 'update property' was based on whether
> the property already exists in the subtree where the node is being
> spliced into.  At the top level of creating a changeset describing the
> overlay, the target node is in the live devicetree, so checking whether
> the property exists in the target node returns the correct result.
> As soon as the changeset creation algorithm recurses into a new node,
> the target is no longer in the live devicetree, but is instead in the
> detached overlay tree, thus all properties are incorrectly found to
> already exist in the target.

When I applied an overlay (that added a few gpio controllers, etc),
the node names for nodes added from the overlay end up NULL.   It
seems related to this patch and the next one.  I haven't completely
root caused this but if I back out to before this patch, the situation
is fixed.

root@arria10:~/unit_tests# ls /sys/bus/platform/drivers/altera_gpio/
bind             ff200010.<NULL>  ff200020.<NULL>  ff200030.<NULL>
uevent           unbind

root@arria10:~/unit_tests# ls /sys/bus/platform/drivers/altera_freeze_br/
bind             ff200450.<NULL>  uevent           unbind

Alan

>
> This fix will expose another devicetree bug that will be fixed
> in the following patch in the series.
>
> When this patch is applied the errors reported by the devictree
> unittest will change, and the unittest results will change from:
>
>    ### dt-test ### end of unittest - 210 passed, 0 failed
>
> to
>
>    ### dt-test ### end of unittest - 203 passed, 7 failed
>
> Signed-off-by: Frank Rowand <frank.rowand@sony.com>
> ---
>  drivers/of/overlay.c | 112 ++++++++++++++++++++++++++++++++++-----------------
>  1 file changed, 74 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
> index 32cfee68f2e3..0b0904f44bc7 100644
> --- a/drivers/of/overlay.c
> +++ b/drivers/of/overlay.c
> @@ -24,6 +24,26 @@
>  #include "of_private.h"
>
>  /**
> + * struct target - info about current target node as recursing through overlay
> + * @np:                        node where current level of overlay will be applied
> + * @in_livetree:       @np is a node in the live devicetree
> + *
> + * Used in the algorithm to create the portion of a changeset that describes
> + * an overlay fragment, which is a devicetree subtree.  Initially @np is a node
> + * in the live devicetree where the overlay subtree is targeted to be grafted
> + * into.  When recursing to the next level of the overlay subtree, the target
> + * also recurses to the next level of the live devicetree, as long as overlay
> + * subtree node also exists in the live devicetree.  When a node in the overlay
> + * subtree does not exist at the same level in the live devicetree, target->np
> + * points to a newly allocated node, and all subsequent targets in the subtree
> + * will be newly allocated nodes.
> + */
> +struct target {
> +       struct device_node *np;
> +       bool in_livetree;
> +};
> +
> +/**
>   * struct fragment - info about fragment nodes in overlay expanded device tree
>   * @target:    target of the overlay operation
>   * @overlay:   pointer to the __overlay__ node
> @@ -72,8 +92,7 @@ static int devicetree_corrupt(void)
>  }
>
>  static int build_changeset_next_level(struct overlay_changeset *ovcs,
> -               struct device_node *target_node,
> -               const struct device_node *overlay_node);
> +               struct target *target, const struct device_node *overlay_node);
>
>  /*
>   * of_resolve_phandles() finds the largest phandle in the live tree.
> @@ -257,14 +276,17 @@ static struct property *dup_and_fixup_symbol_prop(
>  /**
>   * add_changeset_property() - add @overlay_prop to overlay changeset
>   * @ovcs:              overlay changeset
> - * @target_node:       where to place @overlay_prop in live tree
> + * @target:            where @overlay_prop will be placed
>   * @overlay_prop:      property to add or update, from overlay tree
>   * @is_symbols_prop:   1 if @overlay_prop is from node "/__symbols__"
>   *
> - * If @overlay_prop does not already exist in @target_node, add changeset entry
> - * to add @overlay_prop in @target_node, else add changeset entry to update
> + * If @overlay_prop does not already exist in live devicetree, add changeset
> + * entry to add @overlay_prop in @target, else add changeset entry to update
>   * value of @overlay_prop.
>   *
> + * @target may be either in the live devicetree or in a new subtree that
> + * is contained in the changeset.
> + *
>   * Some special properties are not updated (no error returned).
>   *
>   * Update of property in symbols node is not allowed.
> @@ -273,20 +295,22 @@ static struct property *dup_and_fixup_symbol_prop(
>   * invalid @overlay.
>   */
>  static int add_changeset_property(struct overlay_changeset *ovcs,
> -               struct device_node *target_node,
> -               struct property *overlay_prop,
> +               struct target *target, struct property *overlay_prop,
>                 bool is_symbols_prop)
>  {
>         struct property *new_prop = NULL, *prop;
>         int ret = 0;
>
> -       prop = of_find_property(target_node, overlay_prop->name, NULL);
> -
>         if (!of_prop_cmp(overlay_prop->name, "name") ||
>             !of_prop_cmp(overlay_prop->name, "phandle") ||
>             !of_prop_cmp(overlay_prop->name, "linux,phandle"))
>                 return 0;
>
> +       if (target->in_livetree)
> +               prop = of_find_property(target->np, overlay_prop->name, NULL);
> +       else
> +               prop = NULL;
> +
>         if (is_symbols_prop) {
>                 if (prop)
>                         return -EINVAL;
> @@ -299,10 +323,10 @@ static int add_changeset_property(struct overlay_changeset *ovcs,
>                 return -ENOMEM;
>
>         if (!prop)
> -               ret = of_changeset_add_property(&ovcs->cset, target_node,
> +               ret = of_changeset_add_property(&ovcs->cset, target->np,
>                                                 new_prop);
>         else
> -               ret = of_changeset_update_property(&ovcs->cset, target_node,
> +               ret = of_changeset_update_property(&ovcs->cset, target->np,
>                                                    new_prop);
>
>         if (ret) {
> @@ -315,14 +339,14 @@ static int add_changeset_property(struct overlay_changeset *ovcs,
>
>  /**
>   * add_changeset_node() - add @node (and children) to overlay changeset
> - * @ovcs:              overlay changeset
> - * @target_node:       where to place @node in live tree
> - * @node:              node from within overlay device tree fragment
> + * @ovcs:      overlay changeset
> + * @target:    where @overlay_prop will be placed in live tree or changeset
> + * @node:      node from within overlay device tree fragment
>   *
> - * If @node does not already exist in @target_node, add changeset entry
> - * to add @node in @target_node.
> + * If @node does not already exist in @target, add changeset entry
> + * to add @node in @target.
>   *
> - * If @node already exists in @target_node, and the existing node has
> + * If @node already exists in @target, and the existing node has
>   * a phandle, the overlay node is not allowed to have a phandle.
>   *
>   * If @node has child nodes, add the children recursively via
> @@ -355,15 +379,16 @@ static int add_changeset_property(struct overlay_changeset *ovcs,
>   * invalid @overlay.
>   */
>  static int add_changeset_node(struct overlay_changeset *ovcs,
> -               struct device_node *target_node, struct device_node *node)
> +               struct target *target, struct device_node *node)
>  {
>         const char *node_kbasename;
>         struct device_node *tchild;
> +       struct target target_child;
>         int ret = 0;
>
>         node_kbasename = kbasename(node->full_name);
>
> -       for_each_child_of_node(target_node, tchild)
> +       for_each_child_of_node(target->np, tchild)
>                 if (!of_node_cmp(node_kbasename, kbasename(tchild->full_name)))
>                         break;
>
> @@ -372,22 +397,28 @@ static int add_changeset_node(struct overlay_changeset *ovcs,
>                 if (!tchild)
>                         return -ENOMEM;
>
> -               tchild->parent = target_node;
> +               tchild->parent = target->np;
>                 of_node_set_flag(tchild, OF_OVERLAY);
>
>                 ret = of_changeset_attach_node(&ovcs->cset, tchild);
>                 if (ret)
>                         return ret;
>
> -               ret = build_changeset_next_level(ovcs, tchild, node);
> +               target_child.np = tchild;
> +               target_child.in_livetree = false;
> +
> +               ret = build_changeset_next_level(ovcs, &target_child, node);
>                 of_node_put(tchild);
>                 return ret;
>         }
>
> -       if (node->phandle && tchild->phandle)
> +       if (node->phandle && tchild->phandle) {
>                 ret = -EINVAL;
> -       else
> -               ret = build_changeset_next_level(ovcs, tchild, node);
> +       } else {
> +               target_child.np = tchild;
> +               target_child.in_livetree = target->in_livetree;
> +               ret = build_changeset_next_level(ovcs, &target_child, node);
> +       }
>         of_node_put(tchild);
>
>         return ret;
> @@ -396,7 +427,7 @@ static int add_changeset_node(struct overlay_changeset *ovcs,
>  /**
>   * build_changeset_next_level() - add level of overlay changeset
>   * @ovcs:              overlay changeset
> - * @target_node:       where to place @overlay_node in live tree
> + * @target:            where to place @overlay_node in live tree
>   * @overlay_node:      node from within an overlay device tree fragment
>   *
>   * Add the properties (if any) and nodes (if any) from @overlay_node to the
> @@ -409,27 +440,26 @@ static int add_changeset_node(struct overlay_changeset *ovcs,
>   * invalid @overlay_node.
>   */
>  static int build_changeset_next_level(struct overlay_changeset *ovcs,
> -               struct device_node *target_node,
> -               const struct device_node *overlay_node)
> +               struct target *target, const struct device_node *overlay_node)
>  {
>         struct device_node *child;
>         struct property *prop;
>         int ret;
>
>         for_each_property_of_node(overlay_node, prop) {
> -               ret = add_changeset_property(ovcs, target_node, prop, 0);
> +               ret = add_changeset_property(ovcs, target, prop, 0);
>                 if (ret) {
>                         pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
> -                                target_node, prop->name, ret);
> +                                target->np, prop->name, ret);
>                         return ret;
>                 }
>         }
>
>         for_each_child_of_node(overlay_node, child) {
> -               ret = add_changeset_node(ovcs, target_node, child);
> +               ret = add_changeset_node(ovcs, target, child);
>                 if (ret) {
>                         pr_debug("Failed to apply node @%pOF/%s, err=%d\n",
> -                                target_node, child->name, ret);
> +                                target->np, child->name, ret);
>                         of_node_put(child);
>                         return ret;
>                 }
> @@ -442,17 +472,17 @@ static int build_changeset_next_level(struct overlay_changeset *ovcs,
>   * Add the properties from __overlay__ node to the @ovcs->cset changeset.
>   */
>  static int build_changeset_symbols_node(struct overlay_changeset *ovcs,
> -               struct device_node *target_node,
> +               struct target *target,
>                 const struct device_node *overlay_symbols_node)
>  {
>         struct property *prop;
>         int ret;
>
>         for_each_property_of_node(overlay_symbols_node, prop) {
> -               ret = add_changeset_property(ovcs, target_node, prop, 1);
> +               ret = add_changeset_property(ovcs, target, prop, 1);
>                 if (ret) {
>                         pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
> -                                target_node, prop->name, ret);
> +                                target->np, prop->name, ret);
>                         return ret;
>                 }
>         }
> @@ -475,6 +505,7 @@ static int build_changeset_symbols_node(struct overlay_changeset *ovcs,
>  static int build_changeset(struct overlay_changeset *ovcs)
>  {
>         struct fragment *fragment;
> +       struct target target;
>         int fragments_count, i, ret;
>
>         /*
> @@ -489,7 +520,9 @@ static int build_changeset(struct overlay_changeset *ovcs)
>         for (i = 0; i < fragments_count; i++) {
>                 fragment = &ovcs->fragments[i];
>
> -               ret = build_changeset_next_level(ovcs, fragment->target,
> +               target.np = fragment->target;
> +               target.in_livetree = true;
> +               ret = build_changeset_next_level(ovcs, &target,
>                                                  fragment->overlay);
>                 if (ret) {
>                         pr_debug("apply failed '%pOF'\n", fragment->target);
> @@ -499,7 +532,10 @@ static int build_changeset(struct overlay_changeset *ovcs)
>
>         if (ovcs->symbols_fragment) {
>                 fragment = &ovcs->fragments[ovcs->count - 1];
> -               ret = build_changeset_symbols_node(ovcs, fragment->target,
> +
> +               target.np = fragment->target;
> +               target.in_livetree = true;
> +               ret = build_changeset_symbols_node(ovcs, &target,
>                                                    fragment->overlay);
>                 if (ret) {
>                         pr_debug("apply failed '%pOF'\n", fragment->target);
> @@ -517,7 +553,7 @@ static int build_changeset(struct overlay_changeset *ovcs)
>   * 1) "target" property containing the phandle of the target
>   * 2) "target-path" property containing the path of the target
>   */
> -static struct device_node *find_target_node(struct device_node *info_node)
> +static struct device_node *find_target(struct device_node *info_node)
>  {
>         struct device_node *node;
>         const char *path;
> @@ -623,7 +659,7 @@ static int init_overlay_changeset(struct overlay_changeset *ovcs,
>
>                 fragment = &fragments[cnt];
>                 fragment->overlay = overlay_node;
> -               fragment->target = find_target_node(node);
> +               fragment->target = find_target(node);
>                 if (!fragment->target) {
>                         of_node_put(fragment->overlay);
>                         ret = -EINVAL;
> --
> Frank Rowand <frank.rowand@sony.com>
>
Frank Rowand Oct. 9, 2018, 11:44 p.m. | #2
On 10/09/18 13:28, Alan Tull wrote:
> On Thu, Oct 4, 2018 at 11:14 PM <frowand.list@gmail.com> wrote:
>>
>> From: Frank Rowand <frank.rowand@sony.com>
>>
> 
> Hi Frank,
> 
>> The changeset entry 'update property' was used for new properties in
>> an overlay instead of 'add property'.
>>
>> The decision of whether to use 'update property' was based on whether
>> the property already exists in the subtree where the node is being
>> spliced into.  At the top level of creating a changeset describing the
>> overlay, the target node is in the live devicetree, so checking whether
>> the property exists in the target node returns the correct result.
>> As soon as the changeset creation algorithm recurses into a new node,
>> the target is no longer in the live devicetree, but is instead in the
>> detached overlay tree, thus all properties are incorrectly found to
>> already exist in the target.
> 
> When I applied an overlay (that added a few gpio controllers, etc),
> the node names for nodes added from the overlay end up NULL.   It

I'll look at this tonight.

-Frank


> seems related to this patch and the next one.  I haven't completely
> root caused this but if I back out to before this patch, the situation
> is fixed.
> 
> root@arria10:~/unit_tests# ls /sys/bus/platform/drivers/altera_gpio/
> bind             ff200010.<NULL>  ff200020.<NULL>  ff200030.<NULL>
> uevent           unbind
> 
> root@arria10:~/unit_tests# ls /sys/bus/platform/drivers/altera_freeze_br/
> bind             ff200450.<NULL>  uevent           unbind
> 
> Alan
> 
>>
>> This fix will expose another devicetree bug that will be fixed
>> in the following patch in the series.
>>
>> When this patch is applied the errors reported by the devictree
>> unittest will change, and the unittest results will change from:
>>
>>    ### dt-test ### end of unittest - 210 passed, 0 failed
>>
>> to
>>
>>    ### dt-test ### end of unittest - 203 passed, 7 failed
>>
>> Signed-off-by: Frank Rowand <frank.rowand@sony.com>
>> ---
>>  drivers/of/overlay.c | 112 ++++++++++++++++++++++++++++++++++-----------------
>>  1 file changed, 74 insertions(+), 38 deletions(-)
>>
>> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
>> index 32cfee68f2e3..0b0904f44bc7 100644
>> --- a/drivers/of/overlay.c
>> +++ b/drivers/of/overlay.c
>> @@ -24,6 +24,26 @@
>>  #include "of_private.h"
>>
>>  /**
>> + * struct target - info about current target node as recursing through overlay
>> + * @np:                        node where current level of overlay will be applied
>> + * @in_livetree:       @np is a node in the live devicetree
>> + *
>> + * Used in the algorithm to create the portion of a changeset that describes
>> + * an overlay fragment, which is a devicetree subtree.  Initially @np is a node
>> + * in the live devicetree where the overlay subtree is targeted to be grafted
>> + * into.  When recursing to the next level of the overlay subtree, the target
>> + * also recurses to the next level of the live devicetree, as long as overlay
>> + * subtree node also exists in the live devicetree.  When a node in the overlay
>> + * subtree does not exist at the same level in the live devicetree, target->np
>> + * points to a newly allocated node, and all subsequent targets in the subtree
>> + * will be newly allocated nodes.
>> + */
>> +struct target {
>> +       struct device_node *np;
>> +       bool in_livetree;
>> +};
>> +
>> +/**
>>   * struct fragment - info about fragment nodes in overlay expanded device tree
>>   * @target:    target of the overlay operation
>>   * @overlay:   pointer to the __overlay__ node
>> @@ -72,8 +92,7 @@ static int devicetree_corrupt(void)
>>  }
>>
>>  static int build_changeset_next_level(struct overlay_changeset *ovcs,
>> -               struct device_node *target_node,
>> -               const struct device_node *overlay_node);
>> +               struct target *target, const struct device_node *overlay_node);
>>
>>  /*
>>   * of_resolve_phandles() finds the largest phandle in the live tree.
>> @@ -257,14 +276,17 @@ static struct property *dup_and_fixup_symbol_prop(
>>  /**
>>   * add_changeset_property() - add @overlay_prop to overlay changeset
>>   * @ovcs:              overlay changeset
>> - * @target_node:       where to place @overlay_prop in live tree
>> + * @target:            where @overlay_prop will be placed
>>   * @overlay_prop:      property to add or update, from overlay tree
>>   * @is_symbols_prop:   1 if @overlay_prop is from node "/__symbols__"
>>   *
>> - * If @overlay_prop does not already exist in @target_node, add changeset entry
>> - * to add @overlay_prop in @target_node, else add changeset entry to update
>> + * If @overlay_prop does not already exist in live devicetree, add changeset
>> + * entry to add @overlay_prop in @target, else add changeset entry to update
>>   * value of @overlay_prop.
>>   *
>> + * @target may be either in the live devicetree or in a new subtree that
>> + * is contained in the changeset.
>> + *
>>   * Some special properties are not updated (no error returned).
>>   *
>>   * Update of property in symbols node is not allowed.
>> @@ -273,20 +295,22 @@ static struct property *dup_and_fixup_symbol_prop(
>>   * invalid @overlay.
>>   */
>>  static int add_changeset_property(struct overlay_changeset *ovcs,
>> -               struct device_node *target_node,
>> -               struct property *overlay_prop,
>> +               struct target *target, struct property *overlay_prop,
>>                 bool is_symbols_prop)
>>  {
>>         struct property *new_prop = NULL, *prop;
>>         int ret = 0;
>>
>> -       prop = of_find_property(target_node, overlay_prop->name, NULL);
>> -
>>         if (!of_prop_cmp(overlay_prop->name, "name") ||
>>             !of_prop_cmp(overlay_prop->name, "phandle") ||
>>             !of_prop_cmp(overlay_prop->name, "linux,phandle"))
>>                 return 0;
>>
>> +       if (target->in_livetree)
>> +               prop = of_find_property(target->np, overlay_prop->name, NULL);
>> +       else
>> +               prop = NULL;
>> +
>>         if (is_symbols_prop) {
>>                 if (prop)
>>                         return -EINVAL;
>> @@ -299,10 +323,10 @@ static int add_changeset_property(struct overlay_changeset *ovcs,
>>                 return -ENOMEM;
>>
>>         if (!prop)
>> -               ret = of_changeset_add_property(&ovcs->cset, target_node,
>> +               ret = of_changeset_add_property(&ovcs->cset, target->np,
>>                                                 new_prop);
>>         else
>> -               ret = of_changeset_update_property(&ovcs->cset, target_node,
>> +               ret = of_changeset_update_property(&ovcs->cset, target->np,
>>                                                    new_prop);
>>
>>         if (ret) {
>> @@ -315,14 +339,14 @@ static int add_changeset_property(struct overlay_changeset *ovcs,
>>
>>  /**
>>   * add_changeset_node() - add @node (and children) to overlay changeset
>> - * @ovcs:              overlay changeset
>> - * @target_node:       where to place @node in live tree
>> - * @node:              node from within overlay device tree fragment
>> + * @ovcs:      overlay changeset
>> + * @target:    where @overlay_prop will be placed in live tree or changeset
>> + * @node:      node from within overlay device tree fragment
>>   *
>> - * If @node does not already exist in @target_node, add changeset entry
>> - * to add @node in @target_node.
>> + * If @node does not already exist in @target, add changeset entry
>> + * to add @node in @target.
>>   *
>> - * If @node already exists in @target_node, and the existing node has
>> + * If @node already exists in @target, and the existing node has
>>   * a phandle, the overlay node is not allowed to have a phandle.
>>   *
>>   * If @node has child nodes, add the children recursively via
>> @@ -355,15 +379,16 @@ static int add_changeset_property(struct overlay_changeset *ovcs,
>>   * invalid @overlay.
>>   */
>>  static int add_changeset_node(struct overlay_changeset *ovcs,
>> -               struct device_node *target_node, struct device_node *node)
>> +               struct target *target, struct device_node *node)
>>  {
>>         const char *node_kbasename;
>>         struct device_node *tchild;
>> +       struct target target_child;
>>         int ret = 0;
>>
>>         node_kbasename = kbasename(node->full_name);
>>
>> -       for_each_child_of_node(target_node, tchild)
>> +       for_each_child_of_node(target->np, tchild)
>>                 if (!of_node_cmp(node_kbasename, kbasename(tchild->full_name)))
>>                         break;
>>
>> @@ -372,22 +397,28 @@ static int add_changeset_node(struct overlay_changeset *ovcs,
>>                 if (!tchild)
>>                         return -ENOMEM;
>>
>> -               tchild->parent = target_node;
>> +               tchild->parent = target->np;
>>                 of_node_set_flag(tchild, OF_OVERLAY);
>>
>>                 ret = of_changeset_attach_node(&ovcs->cset, tchild);
>>                 if (ret)
>>                         return ret;
>>
>> -               ret = build_changeset_next_level(ovcs, tchild, node);
>> +               target_child.np = tchild;
>> +               target_child.in_livetree = false;
>> +
>> +               ret = build_changeset_next_level(ovcs, &target_child, node);
>>                 of_node_put(tchild);
>>                 return ret;
>>         }
>>
>> -       if (node->phandle && tchild->phandle)
>> +       if (node->phandle && tchild->phandle) {
>>                 ret = -EINVAL;
>> -       else
>> -               ret = build_changeset_next_level(ovcs, tchild, node);
>> +       } else {
>> +               target_child.np = tchild;
>> +               target_child.in_livetree = target->in_livetree;
>> +               ret = build_changeset_next_level(ovcs, &target_child, node);
>> +       }
>>         of_node_put(tchild);
>>
>>         return ret;
>> @@ -396,7 +427,7 @@ static int add_changeset_node(struct overlay_changeset *ovcs,
>>  /**
>>   * build_changeset_next_level() - add level of overlay changeset
>>   * @ovcs:              overlay changeset
>> - * @target_node:       where to place @overlay_node in live tree
>> + * @target:            where to place @overlay_node in live tree
>>   * @overlay_node:      node from within an overlay device tree fragment
>>   *
>>   * Add the properties (if any) and nodes (if any) from @overlay_node to the
>> @@ -409,27 +440,26 @@ static int add_changeset_node(struct overlay_changeset *ovcs,
>>   * invalid @overlay_node.
>>   */
>>  static int build_changeset_next_level(struct overlay_changeset *ovcs,
>> -               struct device_node *target_node,
>> -               const struct device_node *overlay_node)
>> +               struct target *target, const struct device_node *overlay_node)
>>  {
>>         struct device_node *child;
>>         struct property *prop;
>>         int ret;
>>
>>         for_each_property_of_node(overlay_node, prop) {
>> -               ret = add_changeset_property(ovcs, target_node, prop, 0);
>> +               ret = add_changeset_property(ovcs, target, prop, 0);
>>                 if (ret) {
>>                         pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
>> -                                target_node, prop->name, ret);
>> +                                target->np, prop->name, ret);
>>                         return ret;
>>                 }
>>         }
>>
>>         for_each_child_of_node(overlay_node, child) {
>> -               ret = add_changeset_node(ovcs, target_node, child);
>> +               ret = add_changeset_node(ovcs, target, child);
>>                 if (ret) {
>>                         pr_debug("Failed to apply node @%pOF/%s, err=%d\n",
>> -                                target_node, child->name, ret);
>> +                                target->np, child->name, ret);
>>                         of_node_put(child);
>>                         return ret;
>>                 }
>> @@ -442,17 +472,17 @@ static int build_changeset_next_level(struct overlay_changeset *ovcs,
>>   * Add the properties from __overlay__ node to the @ovcs->cset changeset.
>>   */
>>  static int build_changeset_symbols_node(struct overlay_changeset *ovcs,
>> -               struct device_node *target_node,
>> +               struct target *target,
>>                 const struct device_node *overlay_symbols_node)
>>  {
>>         struct property *prop;
>>         int ret;
>>
>>         for_each_property_of_node(overlay_symbols_node, prop) {
>> -               ret = add_changeset_property(ovcs, target_node, prop, 1);
>> +               ret = add_changeset_property(ovcs, target, prop, 1);
>>                 if (ret) {
>>                         pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
>> -                                target_node, prop->name, ret);
>> +                                target->np, prop->name, ret);
>>                         return ret;
>>                 }
>>         }
>> @@ -475,6 +505,7 @@ static int build_changeset_symbols_node(struct overlay_changeset *ovcs,
>>  static int build_changeset(struct overlay_changeset *ovcs)
>>  {
>>         struct fragment *fragment;
>> +       struct target target;
>>         int fragments_count, i, ret;
>>
>>         /*
>> @@ -489,7 +520,9 @@ static int build_changeset(struct overlay_changeset *ovcs)
>>         for (i = 0; i < fragments_count; i++) {
>>                 fragment = &ovcs->fragments[i];
>>
>> -               ret = build_changeset_next_level(ovcs, fragment->target,
>> +               target.np = fragment->target;
>> +               target.in_livetree = true;
>> +               ret = build_changeset_next_level(ovcs, &target,
>>                                                  fragment->overlay);
>>                 if (ret) {
>>                         pr_debug("apply failed '%pOF'\n", fragment->target);
>> @@ -499,7 +532,10 @@ static int build_changeset(struct overlay_changeset *ovcs)
>>
>>         if (ovcs->symbols_fragment) {
>>                 fragment = &ovcs->fragments[ovcs->count - 1];
>> -               ret = build_changeset_symbols_node(ovcs, fragment->target,
>> +
>> +               target.np = fragment->target;
>> +               target.in_livetree = true;
>> +               ret = build_changeset_symbols_node(ovcs, &target,
>>                                                    fragment->overlay);
>>                 if (ret) {
>>                         pr_debug("apply failed '%pOF'\n", fragment->target);
>> @@ -517,7 +553,7 @@ static int build_changeset(struct overlay_changeset *ovcs)
>>   * 1) "target" property containing the phandle of the target
>>   * 2) "target-path" property containing the path of the target
>>   */
>> -static struct device_node *find_target_node(struct device_node *info_node)
>> +static struct device_node *find_target(struct device_node *info_node)
>>  {
>>         struct device_node *node;
>>         const char *path;
>> @@ -623,7 +659,7 @@ static int init_overlay_changeset(struct overlay_changeset *ovcs,
>>
>>                 fragment = &fragments[cnt];
>>                 fragment->overlay = overlay_node;
>> -               fragment->target = find_target_node(node);
>> +               fragment->target = find_target(node);
>>                 if (!fragment->target) {
>>                         of_node_put(fragment->overlay);
>>                         ret = -EINVAL;
>> --
>> Frank Rowand <frank.rowand@sony.com>
>>
>

Patch

diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index 32cfee68f2e3..0b0904f44bc7 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -24,6 +24,26 @@ 
 #include "of_private.h"
 
 /**
+ * struct target - info about current target node as recursing through overlay
+ * @np:			node where current level of overlay will be applied
+ * @in_livetree:	@np is a node in the live devicetree
+ *
+ * Used in the algorithm to create the portion of a changeset that describes
+ * an overlay fragment, which is a devicetree subtree.  Initially @np is a node
+ * in the live devicetree where the overlay subtree is targeted to be grafted
+ * into.  When recursing to the next level of the overlay subtree, the target
+ * also recurses to the next level of the live devicetree, as long as overlay
+ * subtree node also exists in the live devicetree.  When a node in the overlay
+ * subtree does not exist at the same level in the live devicetree, target->np
+ * points to a newly allocated node, and all subsequent targets in the subtree
+ * will be newly allocated nodes.
+ */
+struct target {
+	struct device_node *np;
+	bool in_livetree;
+};
+
+/**
  * struct fragment - info about fragment nodes in overlay expanded device tree
  * @target:	target of the overlay operation
  * @overlay:	pointer to the __overlay__ node
@@ -72,8 +92,7 @@  static int devicetree_corrupt(void)
 }
 
 static int build_changeset_next_level(struct overlay_changeset *ovcs,
-		struct device_node *target_node,
-		const struct device_node *overlay_node);
+		struct target *target, const struct device_node *overlay_node);
 
 /*
  * of_resolve_phandles() finds the largest phandle in the live tree.
@@ -257,14 +276,17 @@  static struct property *dup_and_fixup_symbol_prop(
 /**
  * add_changeset_property() - add @overlay_prop to overlay changeset
  * @ovcs:		overlay changeset
- * @target_node:	where to place @overlay_prop in live tree
+ * @target:		where @overlay_prop will be placed
  * @overlay_prop:	property to add or update, from overlay tree
  * @is_symbols_prop:	1 if @overlay_prop is from node "/__symbols__"
  *
- * If @overlay_prop does not already exist in @target_node, add changeset entry
- * to add @overlay_prop in @target_node, else add changeset entry to update
+ * If @overlay_prop does not already exist in live devicetree, add changeset
+ * entry to add @overlay_prop in @target, else add changeset entry to update
  * value of @overlay_prop.
  *
+ * @target may be either in the live devicetree or in a new subtree that
+ * is contained in the changeset.
+ *
  * Some special properties are not updated (no error returned).
  *
  * Update of property in symbols node is not allowed.
@@ -273,20 +295,22 @@  static struct property *dup_and_fixup_symbol_prop(
  * invalid @overlay.
  */
 static int add_changeset_property(struct overlay_changeset *ovcs,
-		struct device_node *target_node,
-		struct property *overlay_prop,
+		struct target *target, struct property *overlay_prop,
 		bool is_symbols_prop)
 {
 	struct property *new_prop = NULL, *prop;
 	int ret = 0;
 
-	prop = of_find_property(target_node, overlay_prop->name, NULL);
-
 	if (!of_prop_cmp(overlay_prop->name, "name") ||
 	    !of_prop_cmp(overlay_prop->name, "phandle") ||
 	    !of_prop_cmp(overlay_prop->name, "linux,phandle"))
 		return 0;
 
+	if (target->in_livetree)
+		prop = of_find_property(target->np, overlay_prop->name, NULL);
+	else
+		prop = NULL;
+
 	if (is_symbols_prop) {
 		if (prop)
 			return -EINVAL;
@@ -299,10 +323,10 @@  static int add_changeset_property(struct overlay_changeset *ovcs,
 		return -ENOMEM;
 
 	if (!prop)
-		ret = of_changeset_add_property(&ovcs->cset, target_node,
+		ret = of_changeset_add_property(&ovcs->cset, target->np,
 						new_prop);
 	else
-		ret = of_changeset_update_property(&ovcs->cset, target_node,
+		ret = of_changeset_update_property(&ovcs->cset, target->np,
 						   new_prop);
 
 	if (ret) {
@@ -315,14 +339,14 @@  static int add_changeset_property(struct overlay_changeset *ovcs,
 
 /**
  * add_changeset_node() - add @node (and children) to overlay changeset
- * @ovcs:		overlay changeset
- * @target_node:	where to place @node in live tree
- * @node:		node from within overlay device tree fragment
+ * @ovcs:	overlay changeset
+ * @target:	where @overlay_prop will be placed in live tree or changeset
+ * @node:	node from within overlay device tree fragment
  *
- * If @node does not already exist in @target_node, add changeset entry
- * to add @node in @target_node.
+ * If @node does not already exist in @target, add changeset entry
+ * to add @node in @target.
  *
- * If @node already exists in @target_node, and the existing node has
+ * If @node already exists in @target, and the existing node has
  * a phandle, the overlay node is not allowed to have a phandle.
  *
  * If @node has child nodes, add the children recursively via
@@ -355,15 +379,16 @@  static int add_changeset_property(struct overlay_changeset *ovcs,
  * invalid @overlay.
  */
 static int add_changeset_node(struct overlay_changeset *ovcs,
-		struct device_node *target_node, struct device_node *node)
+		struct target *target, struct device_node *node)
 {
 	const char *node_kbasename;
 	struct device_node *tchild;
+	struct target target_child;
 	int ret = 0;
 
 	node_kbasename = kbasename(node->full_name);
 
-	for_each_child_of_node(target_node, tchild)
+	for_each_child_of_node(target->np, tchild)
 		if (!of_node_cmp(node_kbasename, kbasename(tchild->full_name)))
 			break;
 
@@ -372,22 +397,28 @@  static int add_changeset_node(struct overlay_changeset *ovcs,
 		if (!tchild)
 			return -ENOMEM;
 
-		tchild->parent = target_node;
+		tchild->parent = target->np;
 		of_node_set_flag(tchild, OF_OVERLAY);
 
 		ret = of_changeset_attach_node(&ovcs->cset, tchild);
 		if (ret)
 			return ret;
 
-		ret = build_changeset_next_level(ovcs, tchild, node);
+		target_child.np = tchild;
+		target_child.in_livetree = false;
+
+		ret = build_changeset_next_level(ovcs, &target_child, node);
 		of_node_put(tchild);
 		return ret;
 	}
 
-	if (node->phandle && tchild->phandle)
+	if (node->phandle && tchild->phandle) {
 		ret = -EINVAL;
-	else
-		ret = build_changeset_next_level(ovcs, tchild, node);
+	} else {
+		target_child.np = tchild;
+		target_child.in_livetree = target->in_livetree;
+		ret = build_changeset_next_level(ovcs, &target_child, node);
+	}
 	of_node_put(tchild);
 
 	return ret;
@@ -396,7 +427,7 @@  static int add_changeset_node(struct overlay_changeset *ovcs,
 /**
  * build_changeset_next_level() - add level of overlay changeset
  * @ovcs:		overlay changeset
- * @target_node:	where to place @overlay_node in live tree
+ * @target:		where to place @overlay_node in live tree
  * @overlay_node:	node from within an overlay device tree fragment
  *
  * Add the properties (if any) and nodes (if any) from @overlay_node to the
@@ -409,27 +440,26 @@  static int add_changeset_node(struct overlay_changeset *ovcs,
  * invalid @overlay_node.
  */
 static int build_changeset_next_level(struct overlay_changeset *ovcs,
-		struct device_node *target_node,
-		const struct device_node *overlay_node)
+		struct target *target, const struct device_node *overlay_node)
 {
 	struct device_node *child;
 	struct property *prop;
 	int ret;
 
 	for_each_property_of_node(overlay_node, prop) {
-		ret = add_changeset_property(ovcs, target_node, prop, 0);
+		ret = add_changeset_property(ovcs, target, prop, 0);
 		if (ret) {
 			pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
-				 target_node, prop->name, ret);
+				 target->np, prop->name, ret);
 			return ret;
 		}
 	}
 
 	for_each_child_of_node(overlay_node, child) {
-		ret = add_changeset_node(ovcs, target_node, child);
+		ret = add_changeset_node(ovcs, target, child);
 		if (ret) {
 			pr_debug("Failed to apply node @%pOF/%s, err=%d\n",
-				 target_node, child->name, ret);
+				 target->np, child->name, ret);
 			of_node_put(child);
 			return ret;
 		}
@@ -442,17 +472,17 @@  static int build_changeset_next_level(struct overlay_changeset *ovcs,
  * Add the properties from __overlay__ node to the @ovcs->cset changeset.
  */
 static int build_changeset_symbols_node(struct overlay_changeset *ovcs,
-		struct device_node *target_node,
+		struct target *target,
 		const struct device_node *overlay_symbols_node)
 {
 	struct property *prop;
 	int ret;
 
 	for_each_property_of_node(overlay_symbols_node, prop) {
-		ret = add_changeset_property(ovcs, target_node, prop, 1);
+		ret = add_changeset_property(ovcs, target, prop, 1);
 		if (ret) {
 			pr_debug("Failed to apply prop @%pOF/%s, err=%d\n",
-				 target_node, prop->name, ret);
+				 target->np, prop->name, ret);
 			return ret;
 		}
 	}
@@ -475,6 +505,7 @@  static int build_changeset_symbols_node(struct overlay_changeset *ovcs,
 static int build_changeset(struct overlay_changeset *ovcs)
 {
 	struct fragment *fragment;
+	struct target target;
 	int fragments_count, i, ret;
 
 	/*
@@ -489,7 +520,9 @@  static int build_changeset(struct overlay_changeset *ovcs)
 	for (i = 0; i < fragments_count; i++) {
 		fragment = &ovcs->fragments[i];
 
-		ret = build_changeset_next_level(ovcs, fragment->target,
+		target.np = fragment->target;
+		target.in_livetree = true;
+		ret = build_changeset_next_level(ovcs, &target,
 						 fragment->overlay);
 		if (ret) {
 			pr_debug("apply failed '%pOF'\n", fragment->target);
@@ -499,7 +532,10 @@  static int build_changeset(struct overlay_changeset *ovcs)
 
 	if (ovcs->symbols_fragment) {
 		fragment = &ovcs->fragments[ovcs->count - 1];
-		ret = build_changeset_symbols_node(ovcs, fragment->target,
+
+		target.np = fragment->target;
+		target.in_livetree = true;
+		ret = build_changeset_symbols_node(ovcs, &target,
 						   fragment->overlay);
 		if (ret) {
 			pr_debug("apply failed '%pOF'\n", fragment->target);
@@ -517,7 +553,7 @@  static int build_changeset(struct overlay_changeset *ovcs)
  * 1) "target" property containing the phandle of the target
  * 2) "target-path" property containing the path of the target
  */
-static struct device_node *find_target_node(struct device_node *info_node)
+static struct device_node *find_target(struct device_node *info_node)
 {
 	struct device_node *node;
 	const char *path;
@@ -623,7 +659,7 @@  static int init_overlay_changeset(struct overlay_changeset *ovcs,
 
 		fragment = &fragments[cnt];
 		fragment->overlay = overlay_node;
-		fragment->target = find_target_node(node);
+		fragment->target = find_target(node);
 		if (!fragment->target) {
 			of_node_put(fragment->overlay);
 			ret = -EINVAL;