of_node_put is needed before discarding a value received from
of_find_node_by_name, eg in error handling code or when the device node is
no longer used.
The semantic match that catches the bug is as follows:
(http://www.emn.fr/x-info/coccinelle/)
// <smpl>
@r exists@
local idexpression struct device_node *n;
position p1, p2;
struct device_node *n1;
statement S;
identifier f;
expression E;
expression *ptr != NULL;
@@
n@p1 = of_find_node_by_name(...)
...
if (!n) S
... when != of_node_put(n)
    when != n1 = f(n,...)
    when != E = n
    when any
    when strict
(
  return \(0\|<+...n...+>\|ptr\);
|
return@p2 ...;
|
  of_node_put(n);
|
  n1 = f(n,...)
|
  E = n
)
@script:python@
p1 << r.p1;
p2 << r.p2;
@@
print "* file: %s of_find_node_by_name %s return %s" % (p1[0].file,p1[0].line,p2[0].line)
// </smpl>
Signed-off-by: Nicolas Palix <npalix@diku.dk>
Signed-off-by: Julia Lawall <julia@diku.dk>
Acked-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
        const u32 *prop;
        int i = 0, offset = 0;
        int err;
-       
+
        np = of_find_node_by_name(NULL, "fan");
        if (!np)
                return -ENODEV;
        }
 
        of_dev = of_platform_device_create(np, "temperatures", NULL);
-       
+       of_node_put(np);
+
        if (of_dev == NULL) {
                printk(KERN_ERR "Can't register temperatures device !\n");
-               of_node_put(np);
                return -ENODEV;
        }
-       
+
        err = device_create_file(&of_dev->dev, &dev_attr_sensor1_temperature);
        err |= device_create_file(&of_dev->dev, &dev_attr_sensor2_temperature);
        err |= device_create_file(&of_dev->dev, &dev_attr_sensor1_limit);