2020-04-25 06:13:13

by Wang Nan

Subject: [PATCH] kbuild: Add $(strip ...) before compare make variable with string

Some of ifneq in Makefile.build works improperly:

ifneq ($(a)$(b)$(c),)
...
endif

Because some make vairable contains unintended spaces introduced by:

a := $(x) $(y)

This commit adds $(strip ...) to some potentially buggy ifneq.

Signed-off-by: Wang Nan <[email protected]>
Cc: Masahiro Yamada <[email protected]>
Cc: Michal Marek <[email protected]>
---
scripts/Makefile.build | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 9fcbfac..b2bc0db 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -46,7 +46,7 @@ include $(kbuild-file)
include scripts/Makefile.lib

# Do not include host rules unless needed
-ifneq ($(hostprogs)$(hostcxxlibs-y)$(hostcxxlibs-m),)
+ifneq ($(strip $(hostprogs) $(hostcxxlibs-y) $(hostcxxlibs-m)),)
include scripts/Makefile.host
endif

@@ -55,7 +55,7 @@ $(warning kbuild: Makefile.build is included improperly)
endif

ifeq ($(need-modorder),)
-ifneq ($(obj-m),)
+ifneq ($(strip $(obj-m)),)
$(warning $(patsubst %.o,'%.ko',$(obj-m)) will not be built even though obj-m is specified.)
$(warning You cannot use subdir-y/m to visit a module Makefile. Use obj-y/m instead.)
endif
@@ -512,7 +512,7 @@ obj-dirs := $(sort $(obj) $(patsubst %/,%, $(dir $(targets))))
# If targets exist, their directories apparently exist. Skip mkdir.
existing-dirs := $(sort $(patsubst %/,%, $(dir $(existing-targets))))
obj-dirs := $(strip $(filter-out $(existing-dirs), $(obj-dirs)))
-ifneq ($(obj-dirs),)
+ifneq ($(strip $(obj-dirs)),)
$(shell mkdir -p $(obj-dirs))
endif
endif
--
2.7.4

2020-04-25 11:38:19

by Masahiro Yamada

Subject: Re: [PATCH] kbuild: Add $(strip ...) before compare make variable with string

On Sat, Apr 25, 2020 at 3:09 PM Wang Nan <[email protected]> wrote:
>
> Some of ifneq in Makefile.build works improperly:
>
> ifneq ($(a)$(b)$(c),)
> ...
> endif
>
> Because some make vairable contains unintended spaces introduced by:
>
> a := $(x) $(y)


Right.
I made a mistake in commit 5f2fb52fac15a

$(hostprogs) always contains a space due to this line:

hostprogs += $(hostprogs-y) $(hostprogs-m)


This line will go away soon, though.



>
> This commit adds $(strip ...) to some potentially buggy ifneq.
>
> Signed-off-by: Wang Nan <[email protected]>
> Cc: Masahiro Yamada <[email protected]>
> Cc: Michal Marek <[email protected]>
> ---
> scripts/Makefile.build | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 9fcbfac..b2bc0db 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -46,7 +46,7 @@ include $(kbuild-file)
> include scripts/Makefile.lib
>
> # Do not include host rules unless needed
> -ifneq ($(hostprogs)$(hostcxxlibs-y)$(hostcxxlibs-m),)
> +ifneq ($(strip $(hostprogs) $(hostcxxlibs-y) $(hostcxxlibs-m)),)

Only this one is correct.


> include scripts/Makefile.host
> endif
>
> @@ -55,7 +55,7 @@ $(warning kbuild: Makefile.build is included improperly)
> endif
>
> ifeq ($(need-modorder),)
> -ifneq ($(obj-m),)
> +ifneq ($(strip $(obj-m)),)


obj-m := $(addprefix $(obj)/,$(obj-m))

has always stripped away spaces.



> $(warning $(patsubst %.o,'%.ko',$(obj-m)) will not be built even though obj-m is specified.)
> $(warning You cannot use subdir-y/m to visit a module Makefile. Use obj-y/m instead.)
> endif
> @@ -512,7 +512,7 @@ obj-dirs := $(sort $(obj) $(patsubst %/,%, $(dir $(targets))))
> # If targets exist, their directories apparently exist. Skip mkdir.
> existing-dirs := $(sort $(patsubst %/,%, $(dir $(existing-targets))))
> obj-dirs := $(strip $(filter-out $(existing-dirs), $(obj-dirs)))
> -ifneq ($(obj-dirs),)


The previous line has $(strip )



> +ifneq ($(strip $(obj-dirs)),)
> $(shell mkdir -p $(obj-dirs))
> endif
> endif
> --
> 2.7.4
>
>


--
Best Regards
Masahiro Yamada