Re: [PATCH v2] dt-bindings: Fix command line length limit calling dt-mk-schema

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Rob,

Thank you for the patch.

On Wed, Apr 22, 2020 at 01:57:08PM -0500, Rob Herring wrote:
> As the number of schemas has increased, we're starting to hit the error
> "execvp: /bin/sh: Argument list too long". This is due to passing all the
> schema files on the command line to dt-mk-schema. It currently is only
> with out of tree builds and is intermittent depending on the file path
> lengths.
> 
> Commit 2ba06cd8565b ("kbuild: Always validate DT binding examples") made
> hitting this proplem more likely since the example validation now always
> gets the full list of schemas.
> 
> Fix this by passing the schema file list in a pipe and using xargs. We end
> up doing the find twice, but the time is insignificant compared to the
> dt-mk-schema time.
> 
> Reported-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Cc: Masahiro Yamada <masahiroy@kernel.org>
> Signed-off-by: Rob Herring <robh@kernel.org>

Tested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> ---
>  Documentation/devicetree/bindings/Makefile | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/Makefile b/Documentation/devicetree/bindings/Makefile
> index 87c76bdabfe6..7782d9985082 100644
> --- a/Documentation/devicetree/bindings/Makefile
> +++ b/Documentation/devicetree/bindings/Makefile
> @@ -14,16 +14,18 @@ $(obj)/%.example.dts: $(src)/%.yaml FORCE
>  # Use full schemas when checking %.example.dts
>  DT_TMP_SCHEMA := $(obj)/processed-schema-examples.yaml
>  
> +find_cmd = find $(srctree)/$(src) \( -name '*.yaml' ! \
> +		-name 'processed-schema*' ! \
> +		-name '*.example.dt.yaml' \)
> +
>  quiet_cmd_mk_schema = SCHEMA  $@
> -      cmd_mk_schema = $(DT_MK_SCHEMA) $(DT_MK_SCHEMA_FLAGS) -o $@ $(real-prereqs)
> +      cmd_mk_schema = rm -f $@ ; \
> +                      $(if $(DT_MK_SCHEMA_FLAGS), \
> +                           echo $(real-prereqs), \
> +                           $(find_cmd)) | \
> +                      xargs $(DT_MK_SCHEMA) $(DT_MK_SCHEMA_FLAGS) >> $@
>  
> -DT_DOCS = $(addprefix $(src)/, \
> -	$(shell \
> -	cd $(srctree)/$(src) && \
> -	find * \( -name '*.yaml' ! \
> -		-name 'processed-schema*' ! \
> -		-name '*.example.dt.yaml' \) \
> -	))
> +DT_DOCS = $(shell $(find_cmd) | sed -e 's|^$(srctree)/||')
>  
>  DT_SCHEMA_FILES ?= $(DT_DOCS)
>  

-- 
Regards,

Laurent Pinchart