drivers/hvc: Add missing of_node_put

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;
statement S1,S2;
expression E,E1;
expression *ptr != NULL;
@@

(
if (!(n@p1 = of_find_node_by_name(...))) S1
|
n@p1 = of_find_node_by_name(...)
)
<... when != of_node_put(n)

    when != if (...) { <+... of_node_put(n) ...+> }
    when != true !n  || ...
    when != n = E
    when != E = n

if (!n || ...) S2
...>
(
return \(0\|<+...n...+>\|ptr\);
|
return@p2 ...;
|
n = E1
|
E1 = 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>

---
 drivers/char/hvc_iseries.c |    4 +++-
 drivers/char/hvc_vio.c     |    4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

index b74a2f8..449727b 100644
@@ -575,8 +575,10 @@ static int __init hvc_find_vtys(void)
 		 * of console adapters.
 		 */
 		if ((num_found >= MAX_NR_HVC_CONSOLES) ||
-				(num_found >= VTTY_PORTS))
+				(num_found >= VTTY_PORTS)) {
+			of_node_put(vty);
 			break;
+		}
 
 		vtermno = of_get_property(vty, "reg", NULL);
 		if (!vtermno)

index 019e0b5..bd62dc8 100644
@@ -153,8 +153,10 @@ static int hvc_find_vtys(void)
 		/* We have statically defined space for only a certain number
 		 * of console adapters.
 		 */
-		if (num_found >= MAX_NR_HVC_CONSOLES)
+		if (num_found >= MAX_NR_HVC_CONSOLES) {
+			of_node_put(vty);
 			break;
+		}
 
 		vtermno = of_get_property(vty, "reg", NULL);
 		if (!vtermno)

Nicolas Palix