[PATCH v2 1/4] kbuild: move W=1 check for scripts/misc-check to top-level Makefile

[PATCH v2 1/4] kbuild: move W=1 check for scripts/misc-check to top-level Makefile

[Masahiro Yamada]

This script is executed only when ${KBUILD_EXTRA_WARN} contains 1.
Move this check to the top-level Makefile to allow more checks to be
easily added to this script.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

(no changes since v1)

 Makefile           | 3 +++
 scripts/misc-check | 9 +--------
 2 files changed, 4 insertions(+), 8 deletions(-)

diff --git a/Makefile b/Makefile
index 61f4e7662192..7a52be3a4b80 100644
--- a/Makefile
+++ b/Makefile
@@ -1824,9 +1824,12 @@ rustfmtcheck: rustfmt
 # Misc
 # ---------------------------------------------------------------------------
 
+# Run misc checks when ${KBUILD_EXTRA_WARN} contains 1
 PHONY += misc-check
+ifneq ($(findstring 1,$(KBUILD_EXTRA_WARN)),)
 misc-check:
 	$(Q)$(srctree)/scripts/misc-check
+endif
 
 all: misc-check
 
diff --git a/scripts/misc-check b/scripts/misc-check
index d40d5484e0c5..f37b2f6931cc 100755
--- a/scripts/misc-check
+++ b/scripts/misc-check
@@ -3,15 +3,8 @@
 
 set -e
 
-# Detect files that are tracked but ignored by git. This is checked only when
-# ${KBUILD_EXTRA_WARN} contains 1, git is installed, and the source tree is
-# tracked by git.
+# Detect files that are tracked but ignored by git.
 check_tracked_ignored_files () {
-	case "${KBUILD_EXTRA_WARN}" in
-	*1*) ;;
-	*) return;;
-	esac
-
 	git -C ${srctree:-.} ls-files -i -c --exclude-per-directory=.gitignore 2>/dev/null |
 		sed 's/$/: warning: ignored by one of the .gitignore files/' >&2
 }
-- 
2.43.0

[PATCH v2 2/4] scripts/misc-check: add double-quotes to satisfy shellcheck

[Masahiro Yamada]

In scripts/misc-check line 8:
        git -C ${srctree:-.} ls-files -i -c --exclude-per-directory=.gitignore 2>/dev/null |
               ^-----------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

Changes in v2:
 - New patch

 scripts/misc-check | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/misc-check b/scripts/misc-check
index f37b2f6931cc..21551d721079 100755
--- a/scripts/misc-check
+++ b/scripts/misc-check
@@ -5,7 +5,7 @@ set -e
 
 # Detect files that are tracked but ignored by git.
 check_tracked_ignored_files () {
-	git -C ${srctree:-.} ls-files -i -c --exclude-per-directory=.gitignore 2>/dev/null |
+	git -C "${srctree:-.}" ls-files -i -c --exclude-per-directory=.gitignore 2>/dev/null |
 		sed 's/$/: warning: ignored by one of the .gitignore files/' >&2
 }
 
-- 
2.43.0

[PATCH v2 3/4] scripts/misc-check: check missing #include <linux/export.h> when W=1

[Masahiro Yamada]

The problem was described in commit 5b20755b7780 ("init: move THIS_MODULE
from <linux/export.h> to <linux/init.h>").

To summarize it again here: <linux/export.h> is included by most C files,
even though only some of them actually export symbols. This is because
some headers, such as include/linux/{module.h,linkage}, needlessly
include <linux/export.h>.

I have added a more detailed explanation in the comments of
scripts/misc-check.

This problem will be fixed in two steps:

 1. Add #include <linux/export.h> to C files that use EXPORT_SYMBOL()
 2. Remove #include <linux/export.h> from header files that do not use
    EXPORT_SYMBOL()

This commit addresses step 1; scripts/misc-check will warn about *.[ch]
files that use EXPORT_SYMBOL() but do not include <linux/export.h>.
This check is only triggered when the kernel is built with W=1.

We need to fix 4000+ files. I hope others will help with this effort.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

Changes in v2:
 - Fix out-of-tree build

 scripts/misc-check | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/scripts/misc-check b/scripts/misc-check
index 21551d721079..edc0e44d96de 100755
--- a/scripts/misc-check
+++ b/scripts/misc-check
@@ -9,4 +9,47 @@ check_tracked_ignored_files () {
 		sed 's/$/: warning: ignored by one of the .gitignore files/' >&2
 }
 
+# Check for missing #include <linux/export.h>
+#
+# The rule for including <linux/export.h> is very simple:
+# Include <linux/export.h> only when you use EXPORT_SYMBOL(). That's it.
+#
+# However, some headers include <linux/export.h> even though they are completely
+# unrelated to EXPORT_SYMBOL().
+#
+# One example is include/linux/module.h. Please note <linux/module.h> and
+# <linux/export.h> are orthogonal. <linux/module.h> should be included by files
+# that can be compiled as modules. In other words, <linux/module.h> should be
+# included by EXPORT_SYMBOL consumers. In contrast, <linux/export.h> should be
+# included from EXPORT_SYMBOL providers, which may or may not be modular.
+# Hence, include/linux/module.h should *not* include <linux/export.h>.
+#
+# Another example is include/linux/linkage.h, which is completely unrelated to
+# EXPORT_SYMBOL(). Worse, it is included by most C files, which means, most C
+# files end up including <linux/export.h>, even though only some of them
+# actually export symbols. Hence, include/linux/linkage.h should *not* include
+# <linux/export.h>.
+#
+# Before fixing such headers, we must ensure that C files using EXPORT_SYMBOL()
+# include <linux/export.h> directly, since many C files currently rely on
+# <linux/export.h> being included indirectly (likely, via <linux/linkage> etc.).
+#
+# Therefore, this check.
+#
+# The problem is simple - the warned files use EXPORT_SYMBOL(), but do not
+# include <linux/export.h>. Please add #include <linux/export.h> to them.
+#
+# If the included headers are sorted alphabetically, please insert
+# <linux/export.h> in the appropriate position to maintain the sort order.
+# For this reason, this script only checks missing <linux/export.h>, but
+# does not automatically fix it.
+check_missing_include_linux_export_h () {
+
+	git -C "${srctree:-.}" grep --files-with-matches -E 'EXPORT_SYMBOL((_NS)?(_GPL)?|_GPL_FOR_MODULES)\(.*\)' \
+	    -- '*.[ch]' :^tools/ :^include/linux/export.h |
+	xargs git -C "${srctree:-.}" grep --files-without-match '#include[[:space:]]*<linux/export\.h>' |
+	xargs printf "%s: warning: EXPORT_SYMBOL() is used, but #include <linux/export.h> is missing\n" >&2
+}
+
 check_tracked_ignored_files
+check_missing_include_linux_export_h
-- 
2.43.0

Re: [PATCH v2 3/4] scripts/misc-check: check missing #include <linux/export.h> when W=1

[Masahiro Yamada]

On Sun, Jun 1, 2025 at 10:32 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> The problem was described in commit 5b20755b7780 ("init: move THIS_MODULE
> from <linux/export.h> to <linux/init.h>").
>
> To summarize it again here: <linux/export.h> is included by most C files,
> even though only some of them actually export symbols. This is because
> some headers, such as include/linux/{module.h,linkage}, needlessly
> include <linux/export.h>.
>
> I have added a more detailed explanation in the comments of
> scripts/misc-check.
>
> This problem will be fixed in two steps:
>
>  1. Add #include <linux/export.h> to C files that use EXPORT_SYMBOL()
>  2. Remove #include <linux/export.h> from header files that do not use
>     EXPORT_SYMBOL()
>
> This commit addresses step 1; scripts/misc-check will warn about *.[ch]
> files that use EXPORT_SYMBOL() but do not include <linux/export.h>.
> This check is only triggered when the kernel is built with W=1.
>
> We need to fix 4000+ files. I hope others will help with this effort.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
>
> Changes in v2:
>  - Fix out-of-tree build
>
>  scripts/misc-check | 43 +++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 43 insertions(+)
>
> diff --git a/scripts/misc-check b/scripts/misc-check
> index 21551d721079..edc0e44d96de 100755
> --- a/scripts/misc-check
> +++ b/scripts/misc-check
> @@ -9,4 +9,47 @@ check_tracked_ignored_files () {
>                 sed 's/$/: warning: ignored by one of the .gitignore files/' >&2
>  }
>
> +# Check for missing #include <linux/export.h>
> +#
> +# The rule for including <linux/export.h> is very simple:
> +# Include <linux/export.h> only when you use EXPORT_SYMBOL(). That's it.
> +#
> +# However, some headers include <linux/export.h> even though they are completely
> +# unrelated to EXPORT_SYMBOL().
> +#
> +# One example is include/linux/module.h. Please note <linux/module.h> and
> +# <linux/export.h> are orthogonal. <linux/module.h> should be included by files
> +# that can be compiled as modules. In other words, <linux/module.h> should be
> +# included by EXPORT_SYMBOL consumers. In contrast, <linux/export.h> should be
> +# included from EXPORT_SYMBOL providers, which may or may not be modular.
> +# Hence, include/linux/module.h should *not* include <linux/export.h>.
> +#
> +# Another example is include/linux/linkage.h, which is completely unrelated to
> +# EXPORT_SYMBOL(). Worse, it is included by most C files, which means, most C
> +# files end up including <linux/export.h>, even though only some of them
> +# actually export symbols. Hence, include/linux/linkage.h should *not* include
> +# <linux/export.h>.
> +#
> +# Before fixing such headers, we must ensure that C files using EXPORT_SYMBOL()
> +# include <linux/export.h> directly, since many C files currently rely on
> +# <linux/export.h> being included indirectly (likely, via <linux/linkage> etc.).
> +#
> +# Therefore, this check.
> +#
> +# The problem is simple - the warned files use EXPORT_SYMBOL(), but do not
> +# include <linux/export.h>. Please add #include <linux/export.h> to them.
> +#
> +# If the included headers are sorted alphabetically, please insert
> +# <linux/export.h> in the appropriate position to maintain the sort order.
> +# For this reason, this script only checks missing <linux/export.h>, but
> +# does not automatically fix it.
> +check_missing_include_linux_export_h () {
> +
> +       git -C "${srctree:-.}" grep --files-with-matches -E 'EXPORT_SYMBOL((_NS)?(_GPL)?|_GPL_FOR_MODULES)\(.*\)' \
> +           -- '*.[ch]' :^tools/ :^include/linux/export.h |
> +       xargs git -C "${srctree:-.}" grep --files-without-match '#include[[:space:]]*<linux/export\.h>' |
> +       xargs printf "%s: warning: EXPORT_SYMBOL() is used, but #include <linux/export.h> is missing\n" >&2


xargs needs the -r option.



diff --git a/scripts/misc-check b/scripts/misc-check
index 51a5841673f7..c421c6cad476 100755
--- a/scripts/misc-check
+++ b/scripts/misc-check
@@ -47,8 +47,8 @@ check_missing_include_linux_export_h () {

        git -C "${srctree:-.}" grep --files-with-matches -E
'EXPORT_SYMBOL((_NS)?(_GPL)?|_GPL_FOR_MODULES)\(.*\)' \
            -- '*.[ch]' :^tools/ :^include/linux/export.h |
-       xargs git -C "${srctree:-.}" grep --files-without-match
'#include[[:space:]]*<linux/export\.h>' |
-       xargs printf "%s: warning: EXPORT_SYMBOL() is used, but
#include <linux/export.h> is missing\n" >&2
+       xargs -r git -C "${srctree:-.}" grep --files-without-match
'#include[[:space:]]*<linux/export\.h>' |
+       xargs -r printf "%s: warning: EXPORT_SYMBOL() is used, but
#include <linux/export.h> is missing\n" >&2
 }

 # If you do not use EXPORT_SYMBOL(), please do not include <linux/export.h>.


-- 
Best Regards
Masahiro Yamada

Re: [PATCH v2 3/4] scripts/misc-check: check missing #include <linux/export.h> when W=1

[Jakub Kicinski]

On Sun,  1 Jun 2025 22:31:29 +0900 Masahiro Yamada wrote:
> The problem was described in commit 5b20755b7780 ("init: move THIS_MODULE
> from <linux/export.h> to <linux/init.h>").
> 
> To summarize it again here: <linux/export.h> is included by most C files,
> even though only some of them actually export symbols. This is because
> some headers, such as include/linux/{module.h,linkage}, needlessly
> include <linux/export.h>.
> 
> I have added a more detailed explanation in the comments of
> scripts/misc-check.
> 
> This problem will be fixed in two steps:
> 
>  1. Add #include <linux/export.h> to C files that use EXPORT_SYMBOL()
>  2. Remove #include <linux/export.h> from header files that do not use
>     EXPORT_SYMBOL()
> 
> This commit addresses step 1; scripts/misc-check will warn about *.[ch]
> files that use EXPORT_SYMBOL() but do not include <linux/export.h>.
> This check is only triggered when the kernel is built with W=1.
> 
> We need to fix 4000+ files. I hope others will help with this effort.

IIUC you made the kernel spew nearly 5000 warnings on every W=1 build
to "encourage" others to help fix a fairly innocuous problem. 
I appreciate the work that goes into separating the headers but it's
hardly urgent enough to force others to scroll thru 5k warnings.

Please LMK if I'm missing some context here, otherwise I think this is
quite antisocial behavior, and the warnings should go back to W=2 until
someone actually cares to fix most of them.

Happy to hear from others.. CC: workflows

> diff --git a/scripts/misc-check b/scripts/misc-check
> index 21551d721079..edc0e44d96de 100755
> --- a/scripts/misc-check
> +++ b/scripts/misc-check
> @@ -9,4 +9,47 @@ check_tracked_ignored_files () {
>  		sed 's/$/: warning: ignored by one of the .gitignore files/' >&2
>  }
>  
> +# Check for missing #include <linux/export.h>
> +#
> +# The rule for including <linux/export.h> is very simple:
> +# Include <linux/export.h> only when you use EXPORT_SYMBOL(). That's it.
> +#
> +# However, some headers include <linux/export.h> even though they are completely
> +# unrelated to EXPORT_SYMBOL().
> +#
> +# One example is include/linux/module.h. Please note <linux/module.h> and
> +# <linux/export.h> are orthogonal. <linux/module.h> should be included by files
> +# that can be compiled as modules. In other words, <linux/module.h> should be
> +# included by EXPORT_SYMBOL consumers. In contrast, <linux/export.h> should be
> +# included from EXPORT_SYMBOL providers, which may or may not be modular.
> +# Hence, include/linux/module.h should *not* include <linux/export.h>.
> +#
> +# Another example is include/linux/linkage.h, which is completely unrelated to
> +# EXPORT_SYMBOL(). Worse, it is included by most C files, which means, most C
> +# files end up including <linux/export.h>, even though only some of them
> +# actually export symbols. Hence, include/linux/linkage.h should *not* include
> +# <linux/export.h>.
> +#
> +# Before fixing such headers, we must ensure that C files using EXPORT_SYMBOL()
> +# include <linux/export.h> directly, since many C files currently rely on
> +# <linux/export.h> being included indirectly (likely, via <linux/linkage> etc.).
> +#
> +# Therefore, this check.
> +#
> +# The problem is simple - the warned files use EXPORT_SYMBOL(), but do not
> +# include <linux/export.h>. Please add #include <linux/export.h> to them.
> +#
> +# If the included headers are sorted alphabetically, please insert
> +# <linux/export.h> in the appropriate position to maintain the sort order.
> +# For this reason, this script only checks missing <linux/export.h>, but
> +# does not automatically fix it.
> +check_missing_include_linux_export_h () {
> +
> +	git -C "${srctree:-.}" grep --files-with-matches -E 'EXPORT_SYMBOL((_NS)?(_GPL)?|_GPL_FOR_MODULES)\(.*\)' \
> +	    -- '*.[ch]' :^tools/ :^include/linux/export.h |
> +	xargs git -C "${srctree:-.}" grep --files-without-match '#include[[:space:]]*<linux/export\.h>' |
> +	xargs printf "%s: warning: EXPORT_SYMBOL() is used, but #include <linux/export.h> is missing\n" >&2
> +}
> +
>  check_tracked_ignored_files
> +check_missing_include_linux_export_h

Re: [PATCH v2 3/4] scripts/misc-check: check missing #include <linux/export.h> when W=1

[Masahiro Yamada]

On Fri, Jun 20, 2025 at 1:01 AM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Sun,  1 Jun 2025 22:31:29 +0900 Masahiro Yamada wrote:
> > The problem was described in commit 5b20755b7780 ("init: move THIS_MODULE
> > from <linux/export.h> to <linux/init.h>").
> >
> > To summarize it again here: <linux/export.h> is included by most C files,
> > even though only some of them actually export symbols. This is because
> > some headers, such as include/linux/{module.h,linkage}, needlessly
> > include <linux/export.h>.
> >
> > I have added a more detailed explanation in the comments of
> > scripts/misc-check.
> >
> > This problem will be fixed in two steps:
> >
> >  1. Add #include <linux/export.h> to C files that use EXPORT_SYMBOL()
> >  2. Remove #include <linux/export.h> from header files that do not use
> >     EXPORT_SYMBOL()
> >
> > This commit addresses step 1; scripts/misc-check will warn about *.[ch]
> > files that use EXPORT_SYMBOL() but do not include <linux/export.h>.
> > This check is only triggered when the kernel is built with W=1.
> >
> > We need to fix 4000+ files. I hope others will help with this effort.
>
> IIUC you made the kernel spew nearly 5000 warnings on every W=1 build
> to "encourage" others to help fix a fairly innocuous problem.
> I appreciate the work that goes into separating the headers but it's
> hardly urgent enough to force others to scroll thru 5k warnings.
>
> Please LMK if I'm missing some context here, otherwise I think this is
> quite antisocial behavior, and the warnings should go back to W=2 until
> someone actually cares to fix most of them.
>
> Happy to hear from others.. CC: workflows


Please see commit a6a7946bd691940cfe7289ae6dfb1f077516df72


-- 
Best Regards
Masahiro Yamada

Re: [PATCH v2 3/4] scripts/misc-check: check missing #include <linux/export.h> when W=1

[Jakub Kicinski]

On Fri, 20 Jun 2025 01:13:28 +0900 Masahiro Yamada wrote:
> > IIUC you made the kernel spew nearly 5000 warnings on every W=1 build
> > to "encourage" others to help fix a fairly innocuous problem.
> > I appreciate the work that goes into separating the headers but it's
> > hardly urgent enough to force others to scroll thru 5k warnings.
> >
> > Please LMK if I'm missing some context here, otherwise I think this is
> > quite antisocial behavior, and the warnings should go back to W=2 until
> > someone actually cares to fix most of them.
> >
> > Happy to hear from others.. CC: workflows  
> 
> Please see commit a6a7946bd691940cfe7289ae6dfb1f077516df72

Thank you.

[PATCH v2 4/4] scripts/misc-check: check unnecessary #include <linux/export.h> when W=1

[Masahiro Yamada]

Another issue with <linux/export.h> is that it is sometimes included
even when EXPORT_SYMBOL() is not used at all.

Some headers (e.g. include/linux/linkage.h>) cannot be fixed for now
for the reason described in the previous commit.

This commit adds a warning for *.c files that include <linux/export.h>
but do not use EXPORT_SYMBOL() when the kernel is built with W=1.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
eries-changes: 2
 - Fix out-of-tree build
---

(no changes since v1)

 scripts/misc-check | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/scripts/misc-check b/scripts/misc-check
index edc0e44d96de..f3b6bdce5fa2 100755
--- a/scripts/misc-check
+++ b/scripts/misc-check
@@ -51,5 +51,17 @@ check_missing_include_linux_export_h () {
 	xargs printf "%s: warning: EXPORT_SYMBOL() is used, but #include <linux/export.h> is missing\n" >&2
 }
 
+# If you do not use EXPORT_SYMBOL(), please do not include <linux/export.h>.
+# Currently, this is checked for *.c files, but not for *.h files, because some
+# *.c files rely on <linux/export.h> being included indirectly.
+check_unnecessary_include_linux_export_h () {
+
+	git -C "${srctree:-.}" grep --files-with-matches '#include[[:space:]]*<linux/export\.h>' \
+	    -- '*.[c]' :^tools/ |
+	xargs git -C "${srctree:-.}" grep --files-without-match -E 'EXPORT_SYMBOL((_NS)?(_GPL)?|_GPL_FOR_MODULES)\(.*\)' |
+	xargs printf "%s: warning: EXPORT_SYMBOL() is not used, but #include <linux/export.h> is present\n" >&2
+}
+
 check_tracked_ignored_files
 check_missing_include_linux_export_h
+check_unnecessary_include_linux_export_h
-- 
2.43.0

Re: [PATCH v2 1/4] kbuild: move W=1 check for scripts/misc-check to top-level Makefile

[Nathan Chancellor]

On Sun, Jun 01, 2025 at 10:31:27PM +0900, Masahiro Yamada wrote:
> This script is executed only when ${KBUILD_EXTRA_WARN} contains 1.
> Move this check to the top-level Makefile to allow more checks to be
> easily added to this script.
> 
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Reviewed-by: Nathan Chancellor <nathan@kernel.org>

> ---
> 
> (no changes since v1)
> 
>  Makefile           | 3 +++
>  scripts/misc-check | 9 +--------
>  2 files changed, 4 insertions(+), 8 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index 61f4e7662192..7a52be3a4b80 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1824,9 +1824,12 @@ rustfmtcheck: rustfmt
>  # Misc
>  # ---------------------------------------------------------------------------
>  
> +# Run misc checks when ${KBUILD_EXTRA_WARN} contains 1
>  PHONY += misc-check
> +ifneq ($(findstring 1,$(KBUILD_EXTRA_WARN)),)
>  misc-check:
>  	$(Q)$(srctree)/scripts/misc-check
> +endif
>  
>  all: misc-check
>  
> diff --git a/scripts/misc-check b/scripts/misc-check
> index d40d5484e0c5..f37b2f6931cc 100755
> --- a/scripts/misc-check
> +++ b/scripts/misc-check
> @@ -3,15 +3,8 @@
>  
>  set -e
>  
> -# Detect files that are tracked but ignored by git. This is checked only when
> -# ${KBUILD_EXTRA_WARN} contains 1, git is installed, and the source tree is
> -# tracked by git.
> +# Detect files that are tracked but ignored by git.
>  check_tracked_ignored_files () {
> -	case "${KBUILD_EXTRA_WARN}" in
> -	*1*) ;;
> -	*) return;;
> -	esac
> -
>  	git -C ${srctree:-.} ls-files -i -c --exclude-per-directory=.gitignore 2>/dev/null |
>  		sed 's/$/: warning: ignored by one of the .gitignore files/' >&2
>  }
> -- 
> 2.43.0
>