Linux kernel stable tree https://git.rulkc.org/pub/scm/linux/kernel/git/stable/linux.git/atom?h=linux-6.10.y 2024-05-09T21:44:35+00:00 2024-05-09T21:44:35+00:00 Alan Maguire alan.maguire@oracle.com 2024-05-07T13:55:14+00:00 urn:sha1:fcd1ed89a0439c45e1336bd9649485c44b7597c7 The btf_features list can be used for pahole v1.26 and later - it is useful because if a feature is not yet implemented it will not exit with a failure message. This will allow us to add feature requests to the pahole options without having to check pahole versions in future; if the version of pahole supports the feature it will be added. Signed-off-by: Alan Maguire <alan.maguire@oracle.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Tested-by: Eduard Zingerman <eddyz87@gmail.com> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20240507135514.490467-1-alan.maguire@oracle.com 2023-10-28T12:10:08+00:00 Masahiro Yamada masahiroy@kernel.org 2023-10-18T15:19:48+00:00 urn:sha1:72d091846de935e0942a8a0f1fe24ff739d85d76 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>