kbuild: Initialize exported variables

The NOSTDINC_FLAGS variable is exported, so it needs to be cleared to
avoid duplicating its content when running make from within make (e.g.
in the packaging targets). This became an issue after commit
9c8fa9bc08f6 ("kbuild: fix if_change and friends to consider argument
order"), which no longer ignores the duplicate options. As Paulo Zanoni
points out, the LDFLAGS_vmlinux variable has the same problem.

Reported-by: "Zanoni, Paulo R" <paulo.r.zanoni@intel.com>
Fixes: 9c8fa9bc08f6 ("kbuild: fix if_change and friends to consider argument order")
Signed-off-by: Michal Marek <mmarek@suse.com>

diff --git a/Makefile b/Makefile
index 0f70de63cfdb450c31e4a346d669047585c8063c..af0c463e908f6db1a11573d869dbcc0fef043c3d 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -363,11 +363,13 @@ CHECK             = sparse
 
 CHECKFLAGS     := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
                  -Wbitwise -Wno-return-void $(CF)
+NOSTDINC_FLAGS  =
 CFLAGS_MODULE   =
 AFLAGS_MODULE   =
 LDFLAGS_MODULE  =
 CFLAGS_KERNEL  =
 AFLAGS_KERNEL  =
+LDFLAGS_vmlinux =
 CFLAGS_GCOV    = -fprofile-arcs -ftest-coverage -fno-tree-loop-im -Wno-maybe-uninitialized
 CFLAGS_KCOV    = -fsanitize-coverage=trace-pc