scripts/coccinelle/free: add NULL test before dev_{put, hold} functions

Since commit b37a466837 ("netdevice: add the case if dev is NULL"),
NULL check before dev_{put, hold} functions is not needed.

Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>

scripts/coccinelle/free/ifnulldev_put.cocci

@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/// Since commit b37a46683739 ("netdevice: add the case if dev is NULL"),
+/// NULL check before dev_{put, hold} functions is not needed.
+///
+/// Based on ifnullfree.cocci by Fabian Frederick.
+///
+// Copyright: (C) 2022 Ziyang Xuan.
+// Comments: -
+// Options: --no-includes --include-headers
+
+virtual patch
+virtual org
+virtual report
+virtual context
+
+@r2 depends on patch@
+expression E;
+@@
+- if (E != NULL)
+(
+  __dev_put(E);
+|
+  dev_put(E);
+|
+  dev_put_track(E, ...);
+|
+  __dev_hold(E);
+|
+  dev_hold(E);
+|
+  dev_hold_track(E, ...);
+)
+
+@r depends on context || report || org @
+expression E;
+position p;
+@@
+
+* if (E != NULL)
+*	\(__dev_put@p\|dev_put@p\|dev_put_track@p\|__dev_hold@p\|dev_hold@p\|
+*         dev_hold_track@p\)(E, ...);
+
+@script:python depends on org@
+p << r.p;
+@@
+
+cocci.print_main("NULL check before dev_{put, hold} functions is not needed", p)
+
+@script:python depends on report@
+p << r.p;
+@@
+
+msg = "WARNING: NULL check before dev_{put, hold} functions is not needed."
+coccilib.report.print_report(p[0], msg)