selftests/bpf: Prevent skeleton generation race

Prevent "classic" and light skeleton generation rules from stomping on
each other's toes due to the use of the same <obj>.linked{1,2,3}.o
naming pattern. There is no coordination and synchronizataion between
.skel.h and .lskel.h rules, so they can easily overwrite each other's
intermediate object files, leading to errors like:

  /bin/sh: line 1: 170928 Bus error               (core dumped)
  /data/users/andriin/linux/tools/testing/selftests/bpf/tools/sbin/bpftool gen skeleton
  /data/users/andriin/linux/tools/testing/selftests/bpf/test_ksyms_weak.linked3.o
  name test_ksyms_weak
  > /data/users/andriin/linux/tools/testing/selftests/bpf/test_ksyms_weak.skel.h
  make: *** [Makefile:507: /data/users/andriin/linux/tools/testing/selftests/bpf/test_ksyms_weak.skel.h] Error 135
  make: *** Deleting file '/data/users/andriin/linux/tools/testing/selftests/bpf/test_ksyms_weak.skel.h'

Fix by using different suffix for light skeleton rule.

Fixes: c48e51c8b07a ("bpf: selftests: Add selftests for module kfunc support")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220509004148.1801791-2-andrii@kernel.org

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index bafdc5373a1382c87ac7be716f71610efc134dbb..6bbc03161544695260b7c2d5c12a8888f5446b69 100644 (file)
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -423,11 +423,11 @@ $(TRUNNER_BPF_SKELS): %.skel.h: %.o $(BPFTOOL) | $(TRUNNER_OUTPUT)
 
 $(TRUNNER_BPF_LSKELS): %.lskel.h: %.o $(BPFTOOL) | $(TRUNNER_OUTPUT)
        $$(call msg,GEN-SKEL,$(TRUNNER_BINARY),$$@)
-       $(Q)$$(BPFTOOL) gen object $$(<:.o=.linked1.o) $$<
-       $(Q)$$(BPFTOOL) gen object $$(<:.o=.linked2.o) $$(<:.o=.linked1.o)
-       $(Q)$$(BPFTOOL) gen object $$(<:.o=.linked3.o) $$(<:.o=.linked2.o)
-       $(Q)diff $$(<:.o=.linked2.o) $$(<:.o=.linked3.o)
-       $(Q)$$(BPFTOOL) gen skeleton -L $$(<:.o=.linked3.o) name $$(notdir $$(<:.o=_lskel)) > $$@
+       $(Q)$$(BPFTOOL) gen object $$(<:.o=.llinked1.o) $$<
+       $(Q)$$(BPFTOOL) gen object $$(<:.o=.llinked2.o) $$(<:.o=.llinked1.o)
+       $(Q)$$(BPFTOOL) gen object $$(<:.o=.llinked3.o) $$(<:.o=.llinked2.o)
+       $(Q)diff $$(<:.o=.llinked2.o) $$(<:.o=.llinked3.o)
+       $(Q)$$(BPFTOOL) gen skeleton -L $$(<:.o=.llinked3.o) name $$(notdir $$(<:.o=_lskel)) > $$@
 
 $(TRUNNER_BPF_SKELS_LINKED): $(TRUNNER_BPF_OBJS) $(BPFTOOL) | $(TRUNNER_OUTPUT)
        $$(call msg,LINK-BPF,$(TRUNNER_BINARY),$$(@:.skel.h=.o))