bpf/preload: Make sure Makefile cleans up after itself, and add .gitignore

The Makefile in bpf/preload builds a local copy of libbpf, but does not properly clean up after itself. This can lead to subsequent compilation failures, since the feature detection cache is kept around which can lead subsequent detection to fail. Fix this by properly setting clean-files, and while we're at it, also add a .gitignore for the directory to ignore the build artifacts. Fixes: d71fa5c ("bpf: Add kernel module with user mode driver that populates bpffs.") Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200927193005.8459-1-toke@redhat.com

Author: tohojo

kernel/bpf/preload/.gitignore

@@ -0,0 +1,4 @@
+/FEATURE-DUMP.libbpf
+/bpf_helper_defs.h
+/feature
+/bpf_preload_umd

kernel/bpf/preload/Makefile

@@ -12,6 +12,8 @@ userccflags += -I $(srctree)/tools/include/ -I $(srctree)/tools/include/uapi \
 
 userprogs := bpf_preload_umd
 
+clean-files := $(userprogs) bpf_helper_defs.h FEATURE-DUMP.libbpf staticobjs/ feature/
+
 bpf_preload_umd-objs := iterators/iterators.o
 bpf_preload_umd-userldlibs := $(LIBBPF_A) -lelf -lz