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Date: Thu, 22 May 2014 17:53:59 -0700
From: Frank Rowand <frowand.list@...il.com>
To: Grant Likely <grant.likely@...aro.org>
CC: linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
David Daney <david.daney@...ium.com>,
Pantelis Antoniou <pantelis.antoniou@...sulko.com>
Subject: Re: [PATCH 2/3] of: Make of_find_node_by_path() handle /aliases
On 5/21/2014 8:13 PM, Grant Likely wrote:
> On Tue, 20 May 2014 19:46:19 -0700, Frank Rowand <frowand.list@...il.com> wrote:
>> On 5/20/2014 7:41 PM, Frank Rowand wrote:
>> < snip >
>>> I will reply to this email with an additional patch that restores the
>>> original behavior.
>> < snip >
>> From: Frank Rowand <frank.rowand@...ymobile.com>
>>
>> If __of_find_node_by_path() returns parent when the remaining portion of the
>> path is "/" then the behavior of of_find_node_by_path() has changed.
>>
>> Previously, adding an extraneous "/" on the end of a path would result
>> in of_find_node_by_path() not finding a match.
>>
>> Signed-off-by: Frank Rowand <frank.rowand@...ymobile.com>
>> ---
>> drivers/of/base.c | 13 ++++++++++++-
>> 1 file changed, 12 insertions(+), 1 deletion(-)
>>
>> Index: b/drivers/of/base.c
>> ===================================================================
>> --- a/drivers/of/base.c
>> +++ b/drivers/of/base.c
>> @@ -778,7 +778,7 @@ static struct device_node *__of_find_nod
>> int len = strchrnul(path, '/') - path;
>>
>> if (!len)
>> - return parent;
>> + return NULL;
>>
>> for_each_child_of_node(parent, child) {
>> const char *name = strrchr(child->full_name, '/');
>> @@ -813,6 +813,17 @@ struct device_node *of_find_node_by_path
>> struct property *pp;
>> unsigned long flags;
>>
>> + if (strcmp(path, "/") == 0) {
>> + raw_spin_lock_irqsave(&devtree_lock, flags);
>> + for (; np; np = np->allnext) {
>> + if (np->full_name && (of_node_cmp(np->full_name, path) == 0)
>> + && of_node_get(np))
>> + break;
>> + }
>> + raw_spin_unlock_irqrestore(&devtree_lock, flags);
>> + return np;
>> + }
>> +
>
> Special case for the root node? Could use a comment, and of_allnodes
> will already point to the root node so this could simply be:
>
> if (strcmp(path, "/") == 0)
> return of_node_get(np);
Yes, your version below is better. I was hoping there was a direct way
of getting the node for "/". It works on my dragonboard.
The comment of why special case "/" is that for the path "/"
__of_find_node_by_path() will return NULL.
>
> Here's a complete patch:
>
> commit adc96db6c39ef7b895e75d30dbc69781f6443f1d
> Author: Grant Likely <grant.likely@...aro.org>
> Date: Thu May 22 11:55:31 2014 +0900
>
> fix trailing '/' case
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index c05a143b6a70..45ac44c8dfea 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -790,7 +790,7 @@ static struct device_node *__of_find_node_by_path(struct device_node *parent,
> int len = strchrnul(path, '/') - path;
>
> if (!len)
> - return parent;
> + return NULL;
>
> __for_each_child_of_node(parent, child) {
> const char *name = strrchr(child->full_name, '/');
> @@ -820,10 +820,13 @@ static struct device_node *__of_find_node_by_path(struct device_node *parent,
> */
> struct device_node *of_find_node_by_path(const char *path)
> {
> - struct device_node *np = of_allnodes;
> + struct device_node *np = NULL;
> struct property *pp;
> unsigned long flags;
>
> + if (strcmp(path, "/") == 0)
> + return of_node_get(of_allnodes);
> +
> /* The path could begin with an alias */
> if (*path != '/') {
> char *p = strchrnul(path, '/');
> @@ -833,7 +836,6 @@ struct device_node *of_find_node_by_path(const char *path)
> if (!of_aliases)
> return NULL;
>
> - np = NULL;
> for_each_property_of_node(of_aliases, pp) {
> if (strlen(pp->name) == len && !strncmp(pp->name, path, len)) {
> np = of_find_node_by_path(pp->value);
> @@ -847,6 +849,8 @@ struct device_node *of_find_node_by_path(const char *path)
>
> /* Step down the tree matching path components */
> raw_spin_lock_irqsave(&devtree_lock, flags);
> + if (!np)
> + np = of_node_get(of_allnodes);
> while (np && *path == '/') {
> path++; /* Increment past '/' delimiter */
> np = __of_find_node_by_path(np, path);
> diff --git a/drivers/of/selftest.c b/drivers/of/selftest.c
> index 10900b18fc06..aeb0b5c8b21d 100644
> --- a/drivers/of/selftest.c
> +++ b/drivers/of/selftest.c
> @@ -42,9 +42,7 @@ static void __init of_selftest_find_node_by_name(void)
>
> /* Test if trailing '/' works */
> np = of_find_node_by_path("/testcase-data/");
> - selftest(np && !strcmp("/testcase-data", np->full_name),
> - "find /testcase-data/ failed\n");
> - of_node_put(np);
> + selftest(!np, "trailing '/' on /testcase-data/ should fail\n");
>
> np = of_find_node_by_path("/testcase-data/phandle-tests/consumer-a");
> selftest(np && !strcmp("/testcase-data/phandle-tests/consumer-a", np->full_name),
> @@ -58,9 +56,7 @@ static void __init of_selftest_find_node_by_name(void)
>
> /* Test if trailing '/' works on aliases */
> np = of_find_node_by_path("testcase-alias/");
> - selftest(np && !strcmp("/testcase-data", np->full_name),
> - "find testcase-alias/ failed\n");
> - of_node_put(np);
> + selftest(!np, "trailing '/' on testcase-alias/ should fail\n");
>
> np = of_find_node_by_path("testcase-alias/phandle-tests/consumer-a");
> selftest(np && !strcmp("/testcase-data/phandle-tests/consumer-a", np->full_name),
>
>
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