coccinelle: Check for missing NULL terminators in of_device_id tables

Failure to terminate an of_device_id table can lead to confusing
failures depending on where the compiler places the array. Add a
check to make sure these tables are terminated. Thanks to Mitchel
Humpherys for coming up with the pattern initially.

Cc: Mitchel Humpherys <mitchelh@codeaurora.org>
Cc: Gilles Muller <Gilles.Muller@lip6.fr>
Cc: Nicolas Palix <nicolas.palix@imag.fr>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: devicetree@vger.kernel.org
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Acked-by: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/coccinelle/misc/of_table.cocci

+/// Make sure of_device_id tables are NULL terminated
+//
+// Keywords: of_table
+// Confidence: Medium
+// Options: --include-headers
+
+virtual patch
+virtual context
+virtual org
+virtual report
+
+@depends on context@
+identifier var, arr;
+expression E;
+@@
+struct of_device_id arr[] = {
+	...,
+	{
+	.var = E,
+*	}
+};
+
+@depends on patch@
+identifier var, arr;
+expression E;
+@@
+struct of_device_id arr[] = {
+	...,
+	{
+	.var = E,
+-	}
++	},
++	{ }
+};
+
+@r depends on org || report@
+position p1;
+identifier var, arr;
+expression E;
+@@
+struct of_device_id arr[] = {
+	...,
+	{
+	.var = E,
+	}
+	@p1
+};
+
+@script:python depends on org@
+p1 << r.p1;
+arr << r.arr;
+@@
+
+cocci.print_main(arr,p1)
+
+@script:python depends on report@
+p1 << r.p1;
+arr << r.arr;
+@@
+
+msg = "%s is not NULL terminated at line %s" % (arr, p1[0].line)
+coccilib.report.print_report(p1[0],msg)