mirror of
https://github.com/torvalds/linux
synced 2024-09-06 01:40:28 +00:00
![Masahiro Yamada](/assets/img/avatar_default.png)
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>
20 lines
638 B
Makefile
20 lines
638 B
Makefile
# SPDX-License-Identifier: GPL-2.0
|
|
|
|
pahole-ver := $(CONFIG_PAHOLE_VERSION)
|
|
pahole-flags-y :=
|
|
|
|
# pahole 1.18 through 1.21 can't handle zero-sized per-CPU vars
|
|
ifeq ($(call test-le, $(pahole-ver), 121),y)
|
|
pahole-flags-$(call test-ge, $(pahole-ver), 118) += --skip_encoding_btf_vars
|
|
endif
|
|
|
|
pahole-flags-$(call test-ge, $(pahole-ver), 121) += --btf_gen_floats
|
|
|
|
pahole-flags-$(call test-ge, $(pahole-ver), 122) += -j
|
|
|
|
pahole-flags-$(CONFIG_PAHOLE_HAS_LANG_EXCLUDE) += --lang_exclude=rust
|
|
|
|
pahole-flags-$(call test-ge, $(pahole-ver), 125) += --skip_encoding_btf_inconsistent_proto --btf_gen_optimized
|
|
|
|
export PAHOLE_FLAGS := $(pahole-flags-y)
|