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: d71fa5c9763c ("bpf: Add kernel module with user mode driver that populates bpffs.")
Signed-off-by: Toke Høiland-Jørgensen <redacted>
---
 kernel/bpf/preload/.gitignore | 4 ++++
 kernel/bpf/preload/Makefile   | 2 ++
 2 files changed, 6 insertions(+)
 create mode 100644 kernel/bpf/preload/.gitignore

diff --git a/kernel/bpf/preload/.gitignore b/kernel/bpf/preload/.gitignore
new file mode 100644
index 000000000000..856a4c5ad0dd
--- /dev/null
+++ b/kernel/bpf/preload/.gitignore

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

diff --git a/kernel/bpf/preload/Makefile b/kernel/bpf/preload/Makefile
index 12c7b62b9b6e..23ee310b6eb4 100644
--- a/kernel/bpf/preload/Makefile
+++ b/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
 

-- 
2.28.0