On Fri, Aug 12, 2022 at 11:36 PM Owen Rafferty <owen@xxxxxxxxxxxxxxxx> wrote:
>
> Remove the bash build dependency for those who otherwise do not
> have it installed. This also provides a significant speedup:
>
> $ make defconfig
> $ make yes2modconfig
>
> ...
>
> $ find . -name "*.o" | grep -v vmlinux | wc
> 3169 3169 89615
> $ export NM=nm
> $ time sh -c 'find . -name "*.o" | grep -v vmlinux | xargs -n1
> ./scripts/check-local-export'
>
> Without patch:
> 0m15.90s real 0m12.17s user 0m05.28s system
>
> With patch:
> dash + nawk
> 0m02.16s real 0m02.92s user 0m00.34s system
>
> dash + busybox awk
> 0m02.36s real 0m03.36s user 0m00.34s system
>
> dash + gawk
> 0m02.07s real 0m03.26s user 0m00.32s system
>
> bash + gawk
> 0m03.55s real 0m05.00s user 0m00.54s system
>
> Signed-off-by: Owen Rafferty <owen@xxxxxxxxxxxxxxxx>
How did you get those small numbers?
The script invokes ${NM} internally,
so it is impossible to become faster than nm.
For me, it takes 55 sec just for running nm.
$ find . -name "*.o" | wc
3191 3191 90085
$ time sh -c 'find . -name "*.o" | grep -v vmlinux | xargs -n1 nm >/dev/null'
nm: ./arch/x86/entry/vdso/vdso32/note.o: no symbols
nm: ./arch/x86/entry/vdso/vdso-note.o: no symbols
real 0m55.783s
user 0m24.887s
sys 0m30.905s
> ---
>
> Notes:
> [v2] commit message updated
>
> scripts/check-local-export | 95 ++++++++++++++++++--------------------
> 1 file changed, 46 insertions(+), 49 deletions(-)
>
> diff --git a/scripts/check-local-export b/scripts/check-local-export
> index 6ccc2f467416..67eaa7cf08c0 100755
> --- a/scripts/check-local-export
> +++ b/scripts/check-local-export
> @@ -1,4 +1,4 @@
> -#!/usr/bin/env bash
> +#!/bin/sh
> # SPDX-License-Identifier: GPL-2.0-only
> #
> # Copyright (C) 2022 Masahiro Yamada <masahiroy@xxxxxxxxxx>
> @@ -8,19 +8,6 @@
>
> set -e
>
> -# catch errors from ${NM}
> -set -o pipefail
> -
> -# Run the last element of a pipeline in the current shell.
> -# Without this, the while-loop would be executed in a subshell, and
> -# the changes made to 'symbol_types' and 'export_symbols' would be lost.
> -shopt -s lastpipe
> -
> -declare -A symbol_types
> -declare -a export_symbols
> -
> -exit_code=0
> -
> # If there is no symbol in the object, ${NM} (both GNU nm and llvm-nm) shows
> # 'no symbols' diagnostic (but exits with 0). It is harmless and hidden by
> # '2>/dev/null'. However, it suppresses real error messages as well. Add a
> @@ -29,43 +16,53 @@ exit_code=0
> # TODO:
> # Use --quiet instead of 2>/dev/null when we upgrade the minimum version of
> # binutils to 2.37, llvm to 13.0.0.
> -# Then, the following line will be really simple:
> -# ${NM} --quiet ${1} |
> +# Then, the following line will be simpler:
> +# { ${NM} --quiet ${1} || kill 0; } |
> +
> +{ ${NM} ${1} 2>/dev/null || { echo "${0}: ${NM} failed" >&2; kill 0; } } |
> +awk -v "file=${1}" '
> +BEGIN {
> + exit_code = 0
> + i = 0
> +}
> +
> +# Skip the line if the number of fields is less than 3.
> +#
> +# case 1)
> +# For undefined symbols, the first field (value) is empty.
> +# The outout looks like this:
> +# " U _printk"
> +# It is unneeded to record undefined symbols.
> +#
> +# case 2)
> +# For Clang LTO, llvm-nm outputs a line with type t but empty name:
> +# "---------------- t"
> +!length($3) {
> + next
> +}
>
> -{ ${NM} ${1} 2>/dev/null || { echo "${0}: ${NM} failed" >&2; false; } } |
> -while read value type name
> -do
> - # Skip the line if the number of fields is less than 3.
> - #
> - # case 1)
> - # For undefined symbols, the first field (value) is empty.
> - # The outout looks like this:
> - # " U _printk"
> - # It is unneeded to record undefined symbols.
> - #
> - # case 2)
> - # For Clang LTO, llvm-nm outputs a line with type 't' but empty name:
> - # "---------------- t"
> - if [[ -z ${name} ]]; then
> - continue
> - fi
> +# save (name, type) in the associative array
> +{ symbol_types[$3]=$2 }
>
> - # save (name, type) in the associative array
> - symbol_types[${name}]=${type}
> +# append the exported symbol to the array
> +($3 ~ /^__ksymtab_/) {
> + export_symbols[i] = $3
> + sub(/^__ksymtab_/, "", export_symbols[i])
> + i++
> +}
>
> - # append the exported symbol to the array
> - if [[ ${name} == __ksymtab_* ]]; then
> - export_symbols+=(${name#__ksymtab_})
> - fi
> -done
> +END {
> + for (j = 0; j < i; ++j) {
> + name = export_symbols[j]
> + # nm(3) says "If lowercase, the symbol is usually local"
> + if (symbol_types[name] ~ /[a-z]/) {
> + printf "%s: error: local symbol %s was exported\n",
> + file, name | "cat 1>&2"
> + exit_code = 1
> + }
> + }
>
> -for name in "${export_symbols[@]}"
> -do
> - # nm(3) says "If lowercase, the symbol is usually local"
> - if [[ ${symbol_types[$name]} =~ [a-z] ]]; then
> - echo "$@: error: local symbol '${name}' was exported" >&2
> - exit_code=1
> - fi
> -done
> + exit exit_code
> +}'
>
> -exit ${exit_code}
> +exit $?
> --
> 2.37.2
>
--
Best Regards
Masahiro Yamada
