Re: [PATCH bpf-next v2] scripts/bpf: Print an error when known types list needs updating

[Yonghong Song <yhs@fb.com>]

On 10/20/19 4:23 AM, Jakub Sitnicki wrote:
> Don't generate a broken bpf_helper_defs.h header if the helper script needs
> updating because it doesn't recognize a newly added type. Instead print an
> error that explains why the build is failing, clean up the partially
> generated header and stop.
> 
> v1->v2:
> - Switched from temporary file to .DELETE_ON_ERROR.
> 
> Fixes: 456a513bb5d4 ("scripts/bpf: Emit an #error directive known types list needs updating")
> Suggested-by: Andrii Nakryiko <andriin@fb.com>
> Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>

Acked-by: Yonghong Song <yhs@fb.com>

> ---
>   scripts/bpf_helpers_doc.py | 4 ++--
>   tools/lib/bpf/Makefile     | 3 +++
>   2 files changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/scripts/bpf_helpers_doc.py b/scripts/bpf_helpers_doc.py
> index 08300bc024da..7548569e8076 100755
> --- a/scripts/bpf_helpers_doc.py
> +++ b/scripts/bpf_helpers_doc.py
> @@ -488,8 +488,8 @@ class PrinterHelpers(Printer):
>               return t
>           if t in self.mapped_types:
>               return self.mapped_types[t]
> -        print("")
> -        print("#error \"Unrecognized type '%s', please add it to known types!\"" % t)
> +        print("Unrecognized type '%s', please add it to known types!" % t,
> +              file=sys.stderr)
>           sys.exit(1)
>   
>       seen_helpers = set()
> diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
> index 75b538577c17..54ff80faa8df 100644
> --- a/tools/lib/bpf/Makefile
> +++ b/tools/lib/bpf/Makefile
> @@ -286,3 +286,6 @@ tags:
>   # Declare the contents of the .PHONY variable as phony.  We keep that
>   # information in a variable so we can use it in if_changed and friends.
>   .PHONY: $(PHONY)
> +
> +# Delete partially updated (corrupted) files on error
> +.DELETE_ON_ERROR:
>