[PATCH] bus: vexpress-config: Add missing of_node_put

On Mon, Jan 25, 2016 at 01:24:44PM +0100, Julia Lawall wrote:

On Mon, 25 Jan 2016, liviu.dudau at arm.com wrote:

quoted

On Fri, Jan 22, 2016 at 11:38:38PM +0530, Amitoj Kaur Chawla wrote:

quoted

for_each_compatible_node performs an of_node_get on each iteration, so
to break out of the loop an of_node_put is required.

Found using Coccinelle. The semantic patch used for this is as follows:

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

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

Signed-off-by: Amitoj Kaur Chawla <redacted>

Hi Amitoj,

quoted

---
 drivers/bus/vexpress-config.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/bus/vexpress-config.c b/drivers/bus/vexpress-config.c
index 6575c0f..c3cb76b 100644
--- a/drivers/bus/vexpress-config.c
+++ b/drivers/bus/vexpress-config.c

@@ -192,8 +192,10 @@ static int __init vexpress_config_init(void)
 	/* Need the config devices early, before the "normal" devices... */
 	for_each_compatible_node(node, NULL, "arm,vexpress,config-bus") {
 		err = vexpress_config_populate(node);
-		if (err)
+		if (err) {
+			of_node_put(node);
 			break;
+		}

This automatically generated patch only solves half of the problem (for the error
path).

quoted

 	}

 	return err;
--
1.9.1

I feel that a better patch would be the following, where the node is released
regardless of the result of vexpress_config_populate().

--8<--------------------------------------------------------------------------

diff --git a/drivers/bus/vexpress-config.c b/drivers/bus/vexpress-config.c
index 6575c0f..c57453d 100644
--- a/drivers/bus/vexpress-config.c
+++ b/drivers/bus/vexpress-config.c

@@ -192,6 +192,7 @@ static int __init vexpress_config_init(void)
 	/* Need the config devices early, before the "normal" devices... */
 	for_each_compatible_node(node, NULL, "arm,vexpress,config-bus") {
 		err = vexpress_config_populate(node);
+		of_node_put(node);

This is not correct.  for_each_compatible_node will do the free if you go
around the loop.  This change would lead to a double free in the non error
case.

You are correct and I withdraw my patch.

For the original patch:

Acked-by: Liviu Dudau <Liviu.Dudau@arm.com>

Best regards,
Liviu

julia

quoted

 		if (err)
 			break;
 	}
-->8--------------------------------------------------------------------------

-- 
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