[PATCH] coccinelle: semantic patch for missing of_node_put

[Wen Yang]

The call to of_parse_phandle()/of_find_node_by_name() ... returns a node
pointer with refcount incremented thus it must be explicitly decremented
after the last usage.

This SmPL is also looking for places where there is an of_node_put on
some path but not on others.

Suggested-by: Julia Lawall <Julia.Lawall@xxxxxxx>
Signed-off-by: Wen Yang <wen.yang99@xxxxxxxxxx>
Cc: Julia Lawall <Julia.Lawall@xxxxxxx>
Cc: Gilles Muller <Gilles.Muller@xxxxxxx>
Cc: Nicolas Palix <nicolas.palix@xxxxxxx>
Cc: Michal Marek <michal.lkml@xxxxxxxxxxx>
Cc: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
Cc: cocci@xxxxxxxxxxxxxxx
---
 scripts/coccinelle/free/of_node_put.cocci | 133 ++++++++++++++++++++++++++++++
 1 file changed, 133 insertions(+)
 create mode 100644 scripts/coccinelle/free/of_node_put.cocci

diff --git a/scripts/coccinelle/free/of_node_put.cocci b/scripts/coccinelle/free/of_node_put.cocci
new file mode 100644
index 0000000..304293c
--- /dev/null
+++ b/scripts/coccinelle/free/of_node_put.cocci
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0
+/// Find missing of_node_put
+///
+// Confidence: Moderate
+// Copyright: (C) 2018-2019 Wen Yang, ZTE.
+// Comments:
+// Options: --no-includes --include-headers
+
+virtual report
+virtual org
+
+@initialize:python@
+@@
+
+msg_prefix = "ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line "
+msg_suffix = ", but without a corresponding object release within this function."
+
+seen = set()
+
+def add_if_not_present (p1, p2):
+    if (p1, p2) not in seen:
+        seen.add((p1, p2))
+        return True
+    return False
+
+@r1 exists@
+local idexpression struct device_node *x;
+expression e, e1;
+position p1, p2;
+identifier f;
+statement S;
+type T;
+@@
+
+(
+x = f@p1(...);
+... when != e = (T)x
+    when any
+    when != true x == NULL
+    when != of_node_put(x)
+    when != of_get_next_parent(x)
+    when != of_find_matching_node(x, ...)
+    when != if (x) { ... of_node_put(x) ... }
+    when != if (x) { ... return x; }
+    when != v4l2_async_notifier_add_fwnode_subdev(<...x...>)
+    when != e1 = of_fwnode_handle(x)
+(
+if (x) { ... when forall
+         of_node_put(x) ... }
+|
+return x;
+|
+return of_fwnode_handle(x);
+|
+return@p2 ...;
+)
+&
+x = f(...)
+...
+if (<+...x...+>) S
+...
+of_node_put(x);
+)
+
+@script:python depends on report && r1@
+p1 << r1.p1;
+p2 << r1.p2;
+@@
+
+if(add_if_not_present(p1[0].line, p2[0].line)):
+  coccilib.report.print_report(p2[0], msg_prefix + p1[0].line + msg_suffix)
+
+@script:python depends on org && r1@
+p1 << r1.p1;
+p2 << r1.p2;
+@@
+
+cocci.print_main("acquired a node pointer with refcount incremented", p1)
+cocci.print_secs("needed of_node_put", p2)
+
+@r2 exists@
+local idexpression struct device_node *x;
+expression e, e1;
+position p1, p2;
+statement S;
+type T;
+@@
+
+x = @p1\(of_find_compatible_node\|of_find_node_by_name\|of_parse_phandle\|
+    of_find_node_by_type\|of_find_node_by_name\|of_find_all_nodes\|
+    of_get_cpu_node\|of_get_parent\|of_get_next_parent\|
+    of_get_next_child\|of_get_next_available_child\|of_get_next_cpu_node\|
+    of_get_compatible_child\|of_get_child_by_name\|of_find_node_opts_by_path\|
+    of_find_node_with_property\|of_find_matching_node_and_match\|of_find_node_by_phandle\|
+    of_parse_phandle\)(...);
+...
+if (x == NULL || ...) S
+... when != e = (T)x
+    when any
+    when != true x == NULL
+    when != of_node_put(x)
+    when != of_get_next_parent(x)
+    when != of_find_matching_node(x, ...)
+    when != if (x) { ... of_node_put(x) ... }
+    when != if (x) { ... return x; }
+    when != v4l2_async_notifier_add_fwnode_subdev(<...x...>)
+    when != e1 = of_fwnode_handle(x)
+(
+if (x) { ... when forall
+         of_node_put(x) ... }
+|
+return x;
+|
+return of_fwnode_handle(x);
+|
+return@p2 ...;
+)
+
+@script:python depends on report && r2@
+p1 << r2.p1;
+p2 << r2.p2;
+@@
+
+if(add_if_not_present(p1[0].line, p2[0].line)):
+  coccilib.report.print_report(p2[0], msg_prefix + p1[0].line + msg_suffix)
+
+@script:python depends on org && r2@
+p1 << r2.p1;
+p2 << r2.p2;
+@@
+
+cocci.print_main("acquired a node pointer with refcount incremented", p1)
+cocci.print_secs("needed of_node_put", p2)
-- 
2.9.5