[PATCH v2] of: resolver: Add missing of_node_get and of_node_put

[PATCH v2] of: resolver: Add missing of_node_get and of_node_put

[Amitoj Kaur Chawla]

In __of_find_node_by_full_name, add an of_node_get when detecting the
desired element, to ensure that it ends up with a reference count that is 
one greater than on entering the function.

Also in __of_find_node_by_full_name, add an of_node_put on breaking
out of the for_each_child_of_node loop, to ensure that the reference
count of the returned value is not double incremented. This change
was made using Coccinelle.

The semantic patch used for this is as follows:

// <smpl>
@@
expression e;
local idexpression n;
@@

 for_each_child_of_node(..., n) {
   ... when != of_node_put(n)
       when != e = n
(
   return n;
|
+  of_node_put(n);
?  return ...;
)
   ...
 }
// </smpl

Finally, add an of_node_put in for_each_child_of_node in the function
__of_adjust_phandle_ref after the value returned by
__of_find_node_by_full_name is no longer useful.

Signed-off-by: Amitoj Kaur Chawla <amitoj1606@gmail.com>
---
Changes in v2:
        -Added an of_node_get and an extra of_node_put in the
         functions __of_find_node_by_full_name and __of_adjust_phandle_ref
         respectively.

 drivers/of/resolver.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/of/resolver.c b/drivers/of/resolver.c
index 640eb4c..d313d49 100644
--- a/drivers/of/resolver.c
+++ b/drivers/of/resolver.c
@@ -36,12 +36,14 @@ static struct device_node *__of_find_node_by_full_name(struct device_node *node,
 
 	/* check */
 	if (of_node_cmp(node->full_name, full_name) == 0)
-		return node;
+		return of_node_get(node);
 
 	for_each_child_of_node(node, child) {
 		found = __of_find_node_by_full_name(child, full_name);
-		if (found != NULL)
+		if (found != NULL) {
+			of_node_put(child);
 			return found;
+		}
 	}
 
 	return NULL;
@@ -174,6 +176,7 @@ static int __of_adjust_phandle_ref(struct device_node *node,
 			if (of_prop_cmp(sprop->name, propstr) == 0)
 				break;
 		}
+		of_node_put(refnode);
 
 		if (!sprop) {
 			pr_err("%s: Could not find property '%s'\n",
-- 
1.9.1

Re: [PATCH v2] of: resolver: Add missing of_node_get and of_node_put

[Rob Herring]

On Wed, Feb 3, 2016 at 12:09 PM, Amitoj Kaur Chawla
<amitoj1606-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> In __of_find_node_by_full_name, add an of_node_get when detecting the
> desired element, to ensure that it ends up with a reference count that is
> one greater than on entering the function.
>
> Also in __of_find_node_by_full_name, add an of_node_put on breaking
> out of the for_each_child_of_node loop, to ensure that the reference
> count of the returned value is not double incremented. This change
> was made using Coccinelle.

Pantelis, are you convinced this is correct (albeit somewhat pointless)?

Rob
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Re: [PATCH v2] of: resolver: Add missing of_node_get and of_node_put

[Pantelis Antoniou]

Hi Rob,

> On Feb 12, 2016, at 01:18 , Rob Herring <robh+dt@kernel.org> wrote:
> 
> On Wed, Feb 3, 2016 at 12:09 PM, Amitoj Kaur Chawla
> <amitoj1606@gmail.com> wrote:
>> In __of_find_node_by_full_name, add an of_node_get when detecting the
>> desired element, to ensure that it ends up with a reference count that is
>> one greater than on entering the function.
>> 
>> Also in __of_find_node_by_full_name, add an of_node_put on breaking
>> out of the for_each_child_of_node loop, to ensure that the reference
>> count of the returned value is not double incremented. This change
>> was made using Coccinelle.
> 
> Pantelis, are you convinced this is correct (albeit somewhat pointless)?
> 

This is good enough. It’s a local method and we won’t ever try to use
it outside of the resolver. We need to fix the reference counting properly
sometime in the future.

> Rob

Regards

— Pantelis