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  3. [PATCH 0/2] bpftool: improve error handing for missing .BTF section
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[PATCH 2/2] makefiles: do not generate empty vmlinux.h

Changbin Du posted 2 patches 2 years, 9 months ago
There is a newer version of this series
[PATCH 2/2] makefiles: do not generate empty vmlinux.h
Posted by Changbin Du 2 years, 9 months ago 
Remove the empty vmlinux.h if bpftool failed to dump btf info.
The emptry vmlinux.h can hide real error when reading output
of make.

Signed-off-by: Changbin Du <changbin.du@gmail.com>
---
 samples/bpf/Makefile                 | 2 +-
 tools/bpf/bpftool/Makefile           | 2 +-
 tools/bpf/runqslower/Makefile        | 2 +-
 tools/perf/Makefile.perf             | 2 +-
 tools/testing/selftests/bpf/Makefile | 2 +-
 5 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 727da3c5879b..ab4788b4883e 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -362,7 +362,7 @@ ifeq ($(VMLINUX_BTF),)
 	$(error Cannot find a vmlinux for VMLINUX_BTF at any of "$(VMLINUX_BTF_PATHS)",\
 		build the kernel or set VMLINUX_BTF or VMLINUX_H variable)
 endif
-	$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@
+	$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@ || { rm $@; exit 1; }
 else
 	$(Q)cp "$(VMLINUX_H)" $@
 endif
diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
index 4a95c017ad4c..d9d6f890884c 100644
--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -177,7 +177,7 @@ BUILD_BPF_SKELS := 1
 
 $(OUTPUT)vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL_BOOTSTRAP)
 ifeq ($(VMLINUX_H),)
-	$(QUIET_GEN)$(BPFTOOL_BOOTSTRAP) btf dump file $< format c > $@
+	$(QUIET_GEN)$(BPFTOOL_BOOTSTRAP) btf dump file $< format c > $@ || { rm $@; exit 1; }
 else
 	$(Q)cp "$(VMLINUX_H)" $@
 endif
diff --git a/tools/bpf/runqslower/Makefile b/tools/bpf/runqslower/Makefile
index 8b3d87b82b7a..2d7911f4666b 100644
--- a/tools/bpf/runqslower/Makefile
+++ b/tools/bpf/runqslower/Makefile
@@ -77,7 +77,7 @@ ifeq ($(VMLINUX_H),)
 			"specify its location." >&2;			       \
 		exit 1;\
 	fi
-	$(QUIET_GEN)$(BPFTOOL) btf dump file $(VMLINUX_BTF_PATH) format c > $@
+	$(QUIET_GEN)$(BPFTOOL) btf dump file $(VMLINUX_BTF_PATH) format c > $@ || { rm $@; exit 1; }
 else
 	$(Q)cp "$(VMLINUX_H)" $@
 endif
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index a432e59afc42..0546d408aa4e 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -1064,7 +1064,7 @@ VMLINUX_BTF ?= $(abspath $(firstword $(wildcard $(VMLINUX_BTF_PATHS))))
 
 $(SKEL_OUT)/vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL)
 ifeq ($(VMLINUX_H),)
-	$(QUIET_GEN)$(BPFTOOL) btf dump file $< format c > $@
+	$(QUIET_GEN)$(BPFTOOL) btf dump file $< format c > $@ || { rm $@; exit 1; }
 else
 	$(Q)cp "$(VMLINUX_H)" $@
 endif
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index e6cf21fad69f..9aa2475b4ac6 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -284,7 +284,7 @@ endif
 $(INCLUDE_DIR)/vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL) | $(INCLUDE_DIR)
 ifeq ($(VMLINUX_H),)
 	$(call msg,GEN,,$@)
-	$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@
+	$(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@ || { rm $@; exit 1; }
 else
 	$(call msg,CP,,$@)
 	$(Q)cp "$(VMLINUX_H)" $@
-- 
2.37.2
Re: [PATCH 2/2] makefiles: do not generate empty vmlinux.h
Posted by Andrii Nakryiko 2 years, 9 months ago 
On Sat, Nov 26, 2022 at 3:13 AM Changbin Du <changbin.du@gmail.com> wrote:
>
> Remove the empty vmlinux.h if bpftool failed to dump btf info.
> The emptry vmlinux.h can hide real error when reading output
> of make.

wouldn't this be better handled by adding .DELETE_ON_ERROR: to
bpftool's Makefile?

>
> Signed-off-by: Changbin Du <changbin.du@gmail.com>
> ---
>  samples/bpf/Makefile                 | 2 +-
>  tools/bpf/bpftool/Makefile           | 2 +-
>  tools/bpf/runqslower/Makefile        | 2 +-
>  tools/perf/Makefile.perf             | 2 +-
>  tools/testing/selftests/bpf/Makefile | 2 +-
>  5 files changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
> index 727da3c5879b..ab4788b4883e 100644
> --- a/samples/bpf/Makefile
> +++ b/samples/bpf/Makefile
> @@ -362,7 +362,7 @@ ifeq ($(VMLINUX_BTF),)
>         $(error Cannot find a vmlinux for VMLINUX_BTF at any of "$(VMLINUX_BTF_PATHS)",\
>                 build the kernel or set VMLINUX_BTF or VMLINUX_H variable)
>  endif
> -       $(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@
> +       $(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@ || { rm $@; exit 1; }
>  else
>         $(Q)cp "$(VMLINUX_H)" $@
>  endif
> diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
> index 4a95c017ad4c..d9d6f890884c 100644
> --- a/tools/bpf/bpftool/Makefile
> +++ b/tools/bpf/bpftool/Makefile
> @@ -177,7 +177,7 @@ BUILD_BPF_SKELS := 1
>
>  $(OUTPUT)vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL_BOOTSTRAP)
>  ifeq ($(VMLINUX_H),)
> -       $(QUIET_GEN)$(BPFTOOL_BOOTSTRAP) btf dump file $< format c > $@
> +       $(QUIET_GEN)$(BPFTOOL_BOOTSTRAP) btf dump file $< format c > $@ || { rm $@; exit 1; }
>  else
>         $(Q)cp "$(VMLINUX_H)" $@
>  endif
> diff --git a/tools/bpf/runqslower/Makefile b/tools/bpf/runqslower/Makefile
> index 8b3d87b82b7a..2d7911f4666b 100644
> --- a/tools/bpf/runqslower/Makefile
> +++ b/tools/bpf/runqslower/Makefile
> @@ -77,7 +77,7 @@ ifeq ($(VMLINUX_H),)
>                         "specify its location." >&2;                           \
>                 exit 1;\
>         fi
> -       $(QUIET_GEN)$(BPFTOOL) btf dump file $(VMLINUX_BTF_PATH) format c > $@
> +       $(QUIET_GEN)$(BPFTOOL) btf dump file $(VMLINUX_BTF_PATH) format c > $@ || { rm $@; exit 1; }
>  else
>         $(Q)cp "$(VMLINUX_H)" $@
>  endif
> diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
> index a432e59afc42..0546d408aa4e 100644
> --- a/tools/perf/Makefile.perf
> +++ b/tools/perf/Makefile.perf
> @@ -1064,7 +1064,7 @@ VMLINUX_BTF ?= $(abspath $(firstword $(wildcard $(VMLINUX_BTF_PATHS))))
>
>  $(SKEL_OUT)/vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL)
>  ifeq ($(VMLINUX_H),)
> -       $(QUIET_GEN)$(BPFTOOL) btf dump file $< format c > $@
> +       $(QUIET_GEN)$(BPFTOOL) btf dump file $< format c > $@ || { rm $@; exit 1; }
>  else
>         $(Q)cp "$(VMLINUX_H)" $@
>  endif
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index e6cf21fad69f..9aa2475b4ac6 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -284,7 +284,7 @@ endif
>  $(INCLUDE_DIR)/vmlinux.h: $(VMLINUX_BTF) $(BPFTOOL) | $(INCLUDE_DIR)
>  ifeq ($(VMLINUX_H),)
>         $(call msg,GEN,,$@)
> -       $(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@
> +       $(Q)$(BPFTOOL) btf dump file $(VMLINUX_BTF) format c > $@ || { rm $@; exit 1; }
>  else
>         $(call msg,CP,,$@)
>         $(Q)cp "$(VMLINUX_H)" $@
> --
> 2.37.2
>
Re: [PATCH 2/2] makefiles: do not generate empty vmlinux.h
Posted by Changbin Du 2 years, 9 months ago 
On Mon, Nov 28, 2022 at 10:00:14PM -0800, Andrii Nakryiko wrote:
> On Sat, Nov 26, 2022 at 3:13 AM Changbin Du <changbin.du@gmail.com> wrote:
> >
> > Remove the empty vmlinux.h if bpftool failed to dump btf info.
> > The emptry vmlinux.h can hide real error when reading output
> > of make.
> 
> wouldn't this be better handled by adding .DELETE_ON_ERROR: to
> bpftool's Makefile?
>
yes, let me replace it.

-- 
Cheers,
Changbin Du

Patchew 2.1-devel-b67e4c2

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