linux-kernel - [PATCH] kbuild: set EXIT trap before creating temporary directory

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Date:   Thu, 28 Jul 2022 12:14:33 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     linux-kbuild@...r.kernel.org
Cc:     David Laight <David.Laight@...lab.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] kbuild: set EXIT trap before creating temporary directory

Swap the order of 'mkdir' and 'trap' just in case the subshell is
interrupted between 'mkdir' and 'trap' although the effect might be
subtle.

Please not this is not a perfect solution to avoid the left-over tmp
directory. There are more cases that miss to remove the tmp directory,
for example:

 - When interrupted, dash does not invoke the EXIT trap (bash does)

 - 'rm' command might be interrupted before removing the directory

I am not addressing all the cases since the tmp directory is harmless
after all.

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

 scripts/Kconfig.include   | 2 +-
 scripts/Makefile.compiler | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
index c1f4222d223d..a0ccceb22cf8 100644
--- a/scripts/Kconfig.include
+++ b/scripts/Kconfig.include
@@ -25,7 +25,7 @@ failure = $(if-success,$(1),n,y)
 
 # $(cc-option,<flag>)
 # Return y if the compiler supports <flag>, n otherwise
-cc-option = $(success,mkdir .tmp_$$; trap "rm -rf .tmp_$$" EXIT; $(CC) -Werror $(CLANG_FLAGS) $(1) -c -x c /dev/null -o .tmp_$$/tmp.o)
+cc-option = $(success,trap "rm -rf .tmp_$$" EXIT; mkdir .tmp_$$; $(CC) -Werror $(CLANG_FLAGS) $(1) -c -x c /dev/null -o .tmp_$$/tmp.o)
 
 # $(ld-option,<flag>)
 # Return y if the linker supports <flag>, n otherwise
diff --git a/scripts/Makefile.compiler b/scripts/Makefile.compiler
index 86ecd2ac874c..94d0d40cddb3 100644
--- a/scripts/Makefile.compiler
+++ b/scripts/Makefile.compiler
@@ -21,8 +21,8 @@ TMPOUT = $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/).tmp_$$$$
 # automatically cleaned up.
 try-run = $(shell set -e;		\
 	TMP=$(TMPOUT)/tmp;		\
-	mkdir -p $(TMPOUT);		\
 	trap "rm -rf $(TMPOUT)" EXIT;	\
+	mkdir -p $(TMPOUT);		\
 	if ($(1)) >/dev/null 2>&1;	\
 	then echo "$(2)";		\
 	else echo "$(3)";		\
-- 
2.34.1