From 60879f2baeea57e2dd2d94c3cb4a00db9f554e7f Mon Sep 17 00:00:00 2001
From: Ben Hutchings <ben@decadent.org.uk>
Date: Sun, 1 Oct 2017 15:29:03 +0100
Subject: [PATCH] liblockdep: Make missing function declarations fatal errors

This should catch use of missing kernel APIs.  Which has happened yet
again.
---
 debian/changelog                          | 2 ++
 debian/rules.d/tools/lib/lockdep/Makefile | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/debian/changelog b/debian/changelog
index ce8ea7f4c..df5a04103 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -31,6 +31,8 @@ linux (4.13.4-1~exp1) UNRELEASED; urgency=medium
   * linux-image-dbg: Override lintian errors binary-from-other-architecture and
     shlib-without-PT_GNU_STACK-section for vDSOs
   * [armhf] dts: exynos: Add dwc3 SUSPHY quirk (Closes: #843448)
+  * liblockdep: Make missing function declarations fatal errors, to catch use
+    of missing kernel APIs
 
   [ Uwe Kleine-König ]
   * [arm64] really enable NET_DSA_MV88E6XXX for Espressobin
diff --git a/debian/rules.d/tools/lib/lockdep/Makefile b/debian/rules.d/tools/lib/lockdep/Makefile
index cb8c122f8..47409087d 100644
--- a/debian/rules.d/tools/lib/lockdep/Makefile
+++ b/debian/rules.d/tools/lib/lockdep/Makefile
@@ -2,6 +2,9 @@ include $(top_rulesdir)/Makefile.inc
 
 DEB_HOST_MULTIARCH := $(shell dpkg-architecture -qDEB_HOST_MULTIARCH)
 
+# Catch use of missing kernel APIs early
+CFLAGS += -Werror=implicit-function-declaration
+
 MAKE_LOCKDEP := +$(MAKE) -C $(top_srcdir)/$(OUTDIR) O=$(CURDIR) V=1 \
 	prefix=/usr libdir_relative=lib/$(DEB_HOST_MULTIARCH) \
 	LIBLOCKDEP_VERSION=$(VERSION) \