[Skiboot] [PATCH 1/3] core/device: Add function to return child node using name and length

[Dan Horák]

On Mon,  2 Jan 2023 08:45:22 +0530
Athira Rajeev <atrajeev at linux.vnet.ibm.com> wrote:

> Add a function dt_find_by_name_len() that returns the child node if
> it matches the first "n" characters of a given name, otherwise NULL.
> This is helpful for cases with node name like: "name at addr". In
> scenarios where nodes are added with "name at addr" format and if the
> value of "addr" is not known, that node can't be matched with node
> name or addr. Hence matching with substring as node name will return
> the expected result. Patch adds dt_find_by_name_len() function
> and testcase for the same in core/test/run-device.c

wouldn't it be better to automatically compare the name up to the "@"
character in the node name when searching for the match instead of
having to hard-code the lengths? I think it should be good enough for
the use case described above.

something like
...
pos = strchr(child->name, '@')
if (!strncmp(child->name, name, pos - child->name))
  ...


		Dan

> Signed-off-by: Athira Rajeev <atrajeev at linux.vnet.ibm.com>
> ---
>  core/device.c          | 20 ++++++++++++++++++++
>  core/test/run-device.c | 11 +++++++++++
>  include/device.h       |  4 ++++
>  3 files changed, 35 insertions(+)
> 
> diff --git a/core/device.c b/core/device.c
> index 2de37c74..72c54e85 100644
> --- a/core/device.c
> +++ b/core/device.c
> @@ -395,6 +395,26 @@ struct dt_node *dt_find_by_name(struct dt_node *root, const char *name)
>  }
>  
>  
> +struct dt_node *dt_find_by_name_len(struct dt_node *root,
> +					const char *name, int len)
> +{
> +	struct dt_node *child, *match;
> +
> +	if (len <= 0)
> +		return NULL;
> +
> +	list_for_each(&root->children, child, list) {
> +		if (!strncmp(child->name, name, len))
> +			return child;
> +
> +		match = dt_find_by_name_len(child, name, len);
> +		if (match)
> +			return match;
> +	}
> +
> +	return NULL;
> +}
> +
>  struct dt_node *dt_new_check(struct dt_node *parent, const char *name)
>  {
>  	struct dt_node *node = dt_find_by_name(parent, name);
> diff --git a/core/test/run-device.c b/core/test/run-device.c
> index 4a12382b..8c552103 100644
> --- a/core/test/run-device.c
> +++ b/core/test/run-device.c
> @@ -466,6 +466,17 @@ int main(void)
>  	new_prop_ph = dt_prop_get_u32(ut2, "something");
>  	assert(!(new_prop_ph == ev1_ph));
>  	dt_free(subtree);
> +
> +	/* Test dt_find_by_name_len */
> +	root = dt_new_root("");
> +	addr1 = dt_new_addr(root, "node", 0x1);
> +	addr2 = dt_new_addr(root, "node0_1", 0x2);
> +	assert(dt_find_by_name(root, "node at 1") == addr1);
> +	assert(dt_find_by_name(root, "node0_1 at 2") == addr2);
> +	assert(dt_find_by_name_len(root, "node@", 5) == addr1);
> +	assert(dt_find_by_name_len(root, "node0_1@", 8) == addr2);
> +	dt_free(root);
> +
>  	return 0;
>  }
>  
> diff --git a/include/device.h b/include/device.h
> index 93fb90ff..f5e0fb79 100644
> --- a/include/device.h
> +++ b/include/device.h
> @@ -184,6 +184,10 @@ struct dt_node *dt_find_by_path(struct dt_node *root, const char *path);
>  /* Find a child node by name */
>  struct dt_node *dt_find_by_name(struct dt_node *root, const char *name);
>  
> +/* Find a child node by name and len */
> +struct dt_node *dt_find_by_name_len(struct dt_node *root,
> +                                        const char *name, int len);
> +
>  /* Find a node by phandle */
>  struct dt_node *dt_find_by_phandle(struct dt_node *root, u32 phandle);
>  
> -- 
> 2.27.0
> 
> _______________________________________________
> Skiboot mailing list
> Skiboot at lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/skiboot