diff options
| author | Masahiro Yamada <masahiroy@kernel.org> | 2023-10-18 18:19:48 +0300 |
|---|---|---|
| committer | Masahiro Yamada <masahiroy@kernel.org> | 2023-10-28 15:10:08 +0300 |
| commit | 72d091846de935e0942a8a0f1fe24ff739d85d76 (patch) | |
| tree | 2b5a31b1ed6279d40ffae00e0bea85898bd46373 /MAINTAINERS | |
| parent | 7f6d8f7e43fb516f060cf71672a922031aa5faa9 (diff) | |
| download | linux-72d091846de935e0942a8a0f1fe24ff739d85d76.tar.xz | |
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 'MAINTAINERS')
| -rw-r--r-- | MAINTAINERS | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/MAINTAINERS b/MAINTAINERS index 35977b269d5e..a08d558b1aaa 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -3742,7 +3742,7 @@ F: net/sched/act_bpf.c F: net/sched/cls_bpf.c F: samples/bpf/ F: scripts/bpf_doc.py -F: scripts/pahole-flags.sh +F: scripts/Makefile.btf F: scripts/pahole-version.sh F: tools/bpf/ F: tools/lib/bpf/ |