[PATCH] coccinelle: semantic patch for missing of_node_put

[Wen Yang]

Looking for places where there is an of_node_put on some paths
but not on others. This SmPL checks that there is a put of the
same data elsewhere in the function, so perhaps that will
alleviate the concern about puts where they are not needed,
while still making it possible to find the ones that are needed.

Suggested-by: Julia Lawall <Julia.Lawall@xxxxxxx>
Signed-off-by: Wen Yang <wen.yang99@xxxxxxxxxx>
Reviewed-by: Julia Lawall <Julia.Lawall@xxxxxxx>
---
 scripts/coccinelle/free/of_node_put.cocci | 57 +++++++++++++++++++++++++++++++
 1 file changed, 57 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..6a29830
--- /dev/null
+++ b/scripts/coccinelle/free/of_node_put.cocci
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0
+/// Find missing of_node_put
+///
+// Confidence: Moderate
+// Comments:
+// Options: --no-includes --include-headers
+
+virtual report
+virtual org
+
+@r exists@
+local idexpression struct device_node *x;
+identifier f;
+statement S,S1,S2;
+expression e,e1;
+position p1,p2;
+type T,T1;
+@@
+
+(
+x = f@p1(...);
+... when != e = (T)x
+if (x == NULL || ...) S1
+else S2
+... when != of_node_put(x)
+ when != if (x) { ... of_node_put(x) ... }
+ when != e1 = (T1)x
+(
+return x;
+|
+return@p2 ...;
+)
+&
+x = f(...)
+...
+if (<+...x...+>) S
+...
+of_node_put(x);
+)
+
+@script:python depends on report@
+p1 << r.p1;
+p2 << r.p2;
+@@
+
+coccilib.report.print_report(p2[0],
+			     "ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line "
+			     + p1[0].line
+			     + ", but without a corresponding object release within this function.")
+
+@script:python depends on org@
+p1 << r.p1;
+p2 << r.p2;
+@@
+
+cocci.print_main("acquired a node pointer with refcount incremented", p1)
+cocci.print_secs("needed of_node_put", p2)
-- 
2.9.5