Re: [PATCH bpf-next v3 2/7] tools/bpftool: Force clean of out-of-tree build

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Tue, Nov 10, 2020 at 8:46 AM Jean-Philippe Brucker
<jean-philippe@linaro.org> wrote:
>
> Cleaning a partial build can fail if the output directory for libbpf
> wasn't created:
>
> $ make -C tools/bpf/bpftool O=/tmp/bpf clean
> /bin/sh: line 0: cd: /tmp/bpf/libbpf/: No such file or directory
> tools/scripts/Makefile.include:17: *** output directory "/tmp/bpf/libbpf/" does not exist.  Stop.
> make: *** [Makefile:36: /tmp/bpf/libbpf/libbpf.a-clean] Error 2
>
> As a result make never gets around to clearing the leftover objects. Add
> the libbpf output directory as clean dependency to ensure clean always
> succeeds (similarly to the "descend" macro). The directory is later
> removed by the clean recipe.
>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> ---
>  tools/bpf/bpftool/Makefile | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
> index f60e6ad3a1df..1358c093b812 100644
> --- a/tools/bpf/bpftool/Makefile
> +++ b/tools/bpf/bpftool/Makefile
> @@ -27,11 +27,13 @@ LIBBPF = $(LIBBPF_PATH)libbpf.a
>
>  BPFTOOL_VERSION ?= $(shell make -rR --no-print-directory -sC ../../.. kernelversion)
>
> -$(LIBBPF): FORCE
> -       $(if $(LIBBPF_OUTPUT),@mkdir -p $(LIBBPF_OUTPUT))
> +$(LIBBPF_OUTPUT):
> +       $(QUIET_MKDIR)mkdir -p $@
> +
> +$(LIBBPF): FORCE | $(LIBBPF_OUTPUT)
>         $(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_OUTPUT) $(LIBBPF_OUTPUT)libbpf.a
>
> -$(LIBBPF)-clean:
> +$(LIBBPF)-clean: $(LIBBPF_OUTPUT)

shouldn't this be `| $(LIBBPF_OUTPUT)` ?

>         $(call QUIET_CLEAN, libbpf)
>         $(Q)$(MAKE) -C $(BPF_DIR) OUTPUT=$(LIBBPF_OUTPUT) clean >/dev/null
>
> --
> 2.29.1
>