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authorMasahiro Yamada <masahiroy@kernel.org>2023-10-19 00:19:48 +0900
committerMasahiro Yamada <masahiroy@kernel.org>2023-10-28 21:10:08 +0900
commit72d091846de935e0942a8a0f1fe24ff739d85d76 (patch)
tree2b5a31b1ed6279d40ffae00e0bea85898bd46373 /Makefile
parent7f6d8f7e43fb516f060cf71672a922031aa5faa9 (diff)
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kbuild: avoid too many execution of scripts/pahole-flags.sh
scripts/pahole-flags.sh is executed so many times. You can confirm it, as follows: $ cat <<EOF >> scripts/pahole-flags.sh > echo "scripts/pahole-flags.sh was executed" >&2 > EOF $ make -s scripts/pahole-flags.sh was executed scripts/pahole-flags.sh was executed scripts/pahole-flags.sh was executed scripts/pahole-flags.sh was executed scripts/pahole-flags.sh was executed [ lots of repeated lines... ] This scripts is executed more than 20 times during the kernel build because PAHOLE_FLAGS is a recursively expanded variable and exported to sub-processes. With GNU Make >= 4.4, it is executed more than 60 times because exported variables are also passed to other $(shell ) invocations. Without careful coding, it is known to cause an exponential fork explosion. [1] The use of $(shell ) in an exported recursive variable is likely wrong because $(shell ) is always evaluated due to the 'export' keyword, and the evaluation can occur multiple times by the nature of recursive variables. Convert the shell script to a Makefile, which is included only when CONFIG_DEBUG_INFO_BTF=y. [1]: https://savannah.gnu.org/bugs/index.php?64746 Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Alan Maguire <alan.maguire@oracle.com> Tested-by: Alan Maguire <alan.maguire@oracle.com> Reviewed-by: Nicolas Schier <n.schier@avm.de> Tested-by: Miguel Ojeda <ojeda@kernel.org> Acked-by: Miguel Ojeda <ojeda@kernel.org> Acked-by: Jiri Olsa <jolsa@kernel.org> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@gmail.com>
Diffstat (limited to 'Makefile')
-rw-r--r--Makefile4
1 files changed, 1 insertions, 3 deletions
diff --git a/Makefile b/Makefile
index fed9a6cc3665..eaddec67e5e1 100644
--- a/Makefile
+++ b/Makefile
@@ -513,8 +513,6 @@ LZ4 = lz4c
XZ = xz
ZSTD = zstd
-PAHOLE_FLAGS = $(shell PAHOLE=$(PAHOLE) $(srctree)/scripts/pahole-flags.sh)
-
CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
-Wbitwise -Wno-return-void -Wno-unknown-attribute $(CF)
NOSTDINC_FLAGS :=
@@ -605,7 +603,6 @@ export KBUILD_RUSTFLAGS RUSTFLAGS_KERNEL RUSTFLAGS_MODULE
export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_RUSTFLAGS_MODULE KBUILD_LDFLAGS_MODULE
export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL KBUILD_RUSTFLAGS_KERNEL
-export PAHOLE_FLAGS
# Files to ignore in find ... statements
@@ -1002,6 +999,7 @@ KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
# include additional Makefiles when needed
include-y := scripts/Makefile.extrawarn
include-$(CONFIG_DEBUG_INFO) += scripts/Makefile.debug
+include-$(CONFIG_DEBUG_INFO_BTF)+= scripts/Makefile.btf
include-$(CONFIG_KASAN) += scripts/Makefile.kasan
include-$(CONFIG_KCSAN) += scripts/Makefile.kcsan
include-$(CONFIG_KMSAN) += scripts/Makefile.kmsan