docs: Kconfig/Makefile: add a check for broken ABI files

The files under Documentation/ABI should follow the syntax
as defined at Documentation/ABI/README.

Allow checking if they're following the syntax by running
the ABI parser script on COMPILE_TEST.

With that, when there's a problem with a file under
Documentation/ABI, it would produce a warning like:

	Warning: file ./Documentation/ABI/testing/sysfs-bus-pci-devices-aer_stats#14:
		What '/sys/bus/pci/devices/<dev>/aer_stats/aer_rootport_total_err_cor' doesn't have a description
	Warning: file ./Documentation/ABI/testing/sysfs-bus-pci-devices-aer_stats#21:
		What '/sys/bus/pci/devices/<dev>/aer_stats/aer_rootport_total_err_fatal' doesn't have a description

Acked-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/57a38de85cb4b548857207cf1fc1bf1ee08613c9.1604042072.git.mchehab+huawei@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/Documentation/Kconfig b/Documentation/Kconfig
index 66046fa..e549a61 100644
--- a/Documentation/Kconfig
+++ b/Documentation/Kconfig
@@ -10,4 +10,14 @@
 
 	   If unsure, select 'N'.
 
+config WARN_ABI_ERRORS
+	bool "Warn if there are errors at ABI files"
+	depends on COMPILE_TEST
+	help
+	   The files under Documentation/ABI should follow what's
+	   described at Documentation/ABI/README. Yet, as they're manually
+	   written, it would be possible that some of those files would
+	   have errors that would break them for being parsed by
+	   scripts/get_abi.pl. Add a check to verify them.
 
+	   If unsure, select 'N'.
diff --git a/Documentation/Makefile b/Documentation/Makefile
index 6b12dd8..6a59a13 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -10,6 +10,11 @@
 $(shell $(srctree)/scripts/documentation-file-ref-check --warn)
 endif
 
+# Check for broken ABI files
+ifeq ($(CONFIG_WARN_ABI_ERRORS),y)
+$(shell $(srctree)/scripts/get_abi.pl validate --dir $(srctree)/Documentation/ABI)
+endif
+
 # You can set these variables from the command line.
 SPHINXBUILD   = sphinx-build
 SPHINXOPTS    =