docs: Kbuild/Makefile: allow check for missing docs at build time

While this doesn't make sense for production Kernels, in order to
avoid regressions when documents are touched, let's add a
check target at the make file.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

4 files changed, 29 insertions, 0 deletions

diff --git a/Documentation/Kconfig b/Documentation/Kconfig
new file mode 100644
index 000000000000..66046fa1c341
--- /dev/null
+++ b/Documentation/Kconfig
@@ -0,0 +1,13 @@
+config WARN_MISSING_DOCUMENTS
+
+        bool "Warn if there's a missing documentation file"
+        depends on COMPILE_TEST
+        help
+           It is not uncommon that a document gets renamed.
+           This option makes the Kernel to check for missing dependencies,
+           warning when something is missing. Works only if the Kernel
+           is built from a git tree.
+
+           If unsure, select 'N'.
+
+
diff --git a/Documentation/Makefile b/Documentation/Makefile
index 2df0789f90b7..e145e4db508b 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -4,6 +4,11 @@
 
 subdir-y := devicetree/bindings/
 
+# Check for broken documentation file references
+ifeq ($(CONFIG_WARN_MISSING_DOCUMENTS),y)
+$(shell $(srctree)/scripts/documentation-file-ref-check --warn)
+endif
+
 # You can set these variables from the command line.
 SPHINXBUILD   = sphinx-build
 SPHINXOPTS    =
diff --git a/Kconfig b/Kconfig
index 48a80beab685..990b0c390dfc 100644
--- a/Kconfig
+++ b/Kconfig
@@ -30,3 +30,5 @@ source "crypto/Kconfig"
 source "lib/Kconfig"
 
 source "lib/Kconfig.debug"
+
+source "Documentation/Kconfig"
diff --git a/scripts/documentation-file-ref-check b/scripts/documentation-file-ref-check
index ff16db269079..440227bb55a9 100755
--- a/scripts/documentation-file-ref-check
+++ b/scripts/documentation-file-ref-check
@@ -22,9 +22,16 @@ $scriptname =~ s,.*/([^/]+/),$1,;
 # Parse arguments
 my $help = 0;
 my $fix = 0;
+my $warn = 0;
+
+if (! -d ".git") {
+        printf "Warning: can't check if file exists, as this is not a git tree";
+        exit 0;
+}
 
 GetOptions(
         'fix' => \$fix,
+        'warn' => \$warn,
         'h|help|usage' => \$help,
 );
 
@@ -139,6 +146,8 @@ while (<IN>) {
                         if (!($ref =~ m/(scripts|Kconfig|Kbuild)/)) {
                                 $broken_ref{$ref}++;
                         }
+                } elsif ($warn) {
+                        print STDERR "Warning: $f references a file that doesn't exist: $fulref\n";
                 } else {
                         print STDERR "$f: $fulref\n";
                 }