linux-kernel - Re: [PATCH] OF: Add [__]of_find_node_by_full

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Date:	Wed, 19 Mar 2014 07:26:16 -0500
From:	Rob Herring <robherring2@...il.com>
To:	Pantelis Antoniou <pantelis.antoniou@...sulko.com>
Cc:	Grant Likely <grant.likely@...retlab.ca>,
	Stephen Warren <swarren@...dotorg.org>,
	Matt Porter <matt.porter@...aro.org>,
	Koen Kooi <koen@...inion.thruhere.net>,
	Alison Chaiken <Alison_Chaiken@...tor.com>,
	Dinh Nguyen <dinh.linux@...il.com>,
	Jan Lubbe <jluebbe@...net.de>,
	Alexander Sverdlin <alexander.sverdlin@....com>,
	Michael Stickel <ms@...able.de>,
	Guenter Roeck <linux@...ck-us.net>,
	Dirk Behme <dirk.behme@...il.com>,
	Alan Tull <delicious.quinoa@...il.com>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Michael Bohan <mbohan@...eaurora.org>,
	Ionut Nicu <ioan.nicu.ext@....com>,
	Michal Simek <monstr@...str.eu>,
	Matt Ranostay <mranostay@...il.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Pete Popov <pete.popov@...sulko.com>,
	Dan Malek <dan.malek@...sulko.com>,
	Georgi Vlaev <georgi.vlaev@...sulko.com>
Subject: Re: [PATCH] OF: Add [__]of_find_node_by_full_name

On Tue, Mar 18, 2014 at 4:52 PM, Pantelis Antoniou
<pantelis.antoniou@...sulko.com> wrote:
> __of_find_node_by_full_name recursively searches for a matching node
> with the given full name without taking any locks.
>
> of_find_node_by_full_name takes locks and takes a reference on the
> matching node.
>
> Signed-off-by: Pantelis Antoniou <pantelis.antoniou@...sulko.com>
> ---
>  drivers/of/base.c  | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/of.h |  4 ++++
>  2 files changed, 62 insertions(+)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index 19bcdb4..08156e6 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -1142,6 +1142,64 @@ static void *of_find_property_value_of_size(const struct device_node *np,
>  }
>
>  /**
> + * __of_find_node_by_full_name - Find a node with the full name recursively
> + * @node:      Root of the tree to perform the search
> + * @full_name: Full name of the node to find.
> + *
> + * Find a node with the give full name by recursively following any of
> + * the child node links.
> + * Returns the matching node, or NULL if not found.
> + * Note that the devtree lock is not taken, so this function is only
> + * safe to call on either detached trees, or when devtree lock is already
> + * taken.
> + */
> +struct device_node *__of_find_node_by_full_name(struct device_node *node,
> +               const char *full_name)
> +{
> +       struct device_node *child, *found;
> +
> +       if (node == NULL)

Just !node is preferred.

> +               return NULL;
> +
> +       /* check */
> +       if (of_node_cmp(node->full_name, full_name) == 0)
> +               return node;
> +
> +       __for_each_child_of_node(node, child) {
> +               found = __of_find_node_by_full_name(child, full_name);
> +               if (found != NULL)

"if (found)" is preferred.

> +                       return found;
> +       }
> +
> +       return NULL;
> +}
> +EXPORT_SYMBOL(__of_find_node_by_full_name);

Does this need to be exported?

In any case, use EXPORT_SYMBOL_GPL.

> +
> +/**
> + * of_find_node_by_full_name - Find a node with the full name recursively
> + * @node:      Root of the tree to perform the search
> + * @full_name: Full name of the node to find.
> + *
> + * Find a node with the give full name by recursively following any of
> + * the child node links.
> + * Returns the matching node (with a ref taken), or NULL if not found.
> + */
> +struct device_node *of_find_node_by_full_name(struct device_node *node,
> +               const char *full_name)
> +{
> +       unsigned long flags;
> +       struct device_node *np;
> +
> +       raw_spin_lock_irqsave(&devtree_lock, flags);
> +       np = of_find_node_by_full_name(node, full_name);

Don't you need __of_find_node_by_full_name here.

> +       of_node_get(np);
> +       raw_spin_unlock_irqrestore(&devtree_lock, flags);
> +
> +       return np;
> +}
> +EXPORT_SYMBOL(of_find_node_by_full_name);
> +
> +/**
>   * of_property_read_u32_index - Find and read a u32 from a multi-value property.
>   *
>   * @np:                device node from which the property value is to be read.
> diff --git a/include/linux/of.h b/include/linux/of.h
> index a8b9dad..bef3d5b 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -223,6 +223,10 @@ extern struct device_node *of_find_matching_node_and_match(
>
>  extern struct device_node *of_find_node_by_path(const char *path);
>  extern struct device_node *of_find_node_by_phandle(phandle handle);
> +struct device_node *__of_find_node_by_full_name(struct device_node *node,
> +                                               const char *full_name);
> +struct device_node *of_find_node_by_full_name(struct device_node *node,
> +                                               const char *full_name);
>  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,
> --
> 1.7.12
>
--
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