From: Tobias Klauser <tklauser@distanz.ch>
Date: Tue, 23 Jun 2020 12:37:10 +0200
Subject: tools, bpftool: Correctly evaluate $(BUILD_BPF_SKELS) in Makefile
Patch-mainline: v5.9-rc1
Git-commit: 9d9d8cc21e3827b89e414f990016836290de3038
References: bsc#1177028

Currently, if the clang-bpf-co-re feature is not available, the build
fails with e.g.

  CC       prog.o
prog.c:1462:10: fatal error: profiler.skel.h: No such file or directory
 1462 | #include "profiler.skel.h"
      |          ^~~~~~~~~~~~~~~~~

This is due to the fact that the BPFTOOL_WITHOUT_SKELETONS macro is not
defined, despite BUILD_BPF_SKELS not being set. Fix this by correctly
evaluating $(BUILD_BPF_SKELS) when deciding on whether to add
-DBPFTOOL_WITHOUT_SKELETONS to CFLAGS.

Fixes: 05aca6da3b5a ("tools/bpftool: Generalize BPF skeleton support and generate vmlinux.h")
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200623103710.10370-1-tklauser@distanz.ch
Acked-by: Gary Lin <glin@suse.com>
---
 tools/bpf/bpftool/Makefile |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -155,7 +155,7 @@ $(OUTPUT)pids.o: $(OUTPUT)pid_iter.skel.
 endif
 endif
 
-CFLAGS += $(if BUILD_BPF_SKELS,,-DBPFTOOL_WITHOUT_SKELETONS)
+CFLAGS += $(if $(BUILD_BPF_SKELS),,-DBPFTOOL_WITHOUT_SKELETONS)
 
 $(OUTPUT)disasm.o: $(srctree)/kernel/bpf/disasm.c
 	$(QUIET_CC)$(CC) $(CFLAGS) -c -MMD -o $@ $<