[PATCH iproute2] configure: require libmnl

[Stephen Hemminger <stephen@networkplumber.org>]

Several users of BPF and other features are trying to build without
libmnl, then complaining that features don't work.  The time has
come to require libmnl to build iproute2.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 configure        | 20 +++++++++++---------
 lib/libnetlink.c | 10 ----------
 2 files changed, 11 insertions(+), 19 deletions(-)

diff --git a/configure b/configure
index 5ef5cd4cf9cd..209d78b6bf19 100755
--- a/configure
+++ b/configure
@@ -281,16 +281,18 @@ check_selinux()
 
 check_mnl()
 {
-	if ${PKG_CONFIG} libmnl --exists
-	then
-		echo "HAVE_MNL:=y" >>$CONFIG
-		echo "yes"
+    if ${PKG_CONFIG} libmnl --exists
+    then
+	echo "HAVE_MNL:=y" >>$CONFIG
+	echo "yes"
 
-		echo 'CFLAGS += -DHAVE_LIBMNL' `${PKG_CONFIG} libmnl --cflags` >>$CONFIG
-		echo 'LDLIBS +=' `${PKG_CONFIG} libmnl --libs` >> $CONFIG
-	else
-		echo "no"
-	fi
+	echo 'CFLAGS += -DHAVE_LIBMNL' `${PKG_CONFIG} libmnl --cflags` >>$CONFIG
+	echo 'LDLIBS +=' `${PKG_CONFIG} libmnl --libs` >> $CONFIG
+    else
+	echo "no"
+	echo "libmnl is required. please install libmnl-dev or libmnl-devel" 1>&2
+	exit 1
+    fi
 }
 
 check_berkeley_db()
diff --git a/lib/libnetlink.c b/lib/libnetlink.c
index 928de1dd16d8..ab8ea85d5dd9 100644
--- a/lib/libnetlink.c
+++ b/lib/libnetlink.c
@@ -35,7 +35,6 @@
 
 int rcvbuf = 1024 * 1024;
 
-#ifdef HAVE_LIBMNL
 #include <libmnl/libmnl.h>
 
 static const enum mnl_attr_data_type extack_policy[NLMSGERR_ATTR_MAX + 1] = {
@@ -116,15 +115,6 @@ int nl_dump_ext_ack(const struct nlmsghdr *nlh, nl_ext_ack_fn_t errfn)
 
 	return 0;
 }
-#else
-#warning "libmnl required for error support"
-
-/* No extended error ack without libmnl */
-int nl_dump_ext_ack(const struct nlmsghdr *nlh, nl_ext_ack_fn_t errfn)
-{
-	return 0;
-}
-#endif
 
 void rtnl_close(struct rtnl_handle *rth)
 {
-- 
2.17.0