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authorMasahiro Yamada <masahiroy@kernel.org>2022-06-08 04:11:00 +0300
committerMasahiro Yamada <masahiroy@kernel.org>2022-06-09 21:47:13 +0300
commitda4288b95baa1c7c9aa8a476f58b37eb238745b0 (patch)
tree4730da2d97ddcfaae4224786c2ecb88c7c337d43 /scripts
parent49c3ca34f7dbe5227c0163cba4deb5d29e145fae (diff)
downloadlinux-da4288b95baa1c7c9aa8a476f58b37eb238745b0.tar.xz
scripts/check-local-export: avoid 'wait $!' for process substitution
Bash 4.4, released in 2016, supports 'wait $!' to check the exit status of a process substitution, but it seems too new. Some people using older bash versions (on CentOS 7, Ubuntu 16.04, etc.) reported an error like this: ./scripts/check-local-export: line 54: wait: pid 17328 is not a child of this shell I used the process substitution to avoid a pipeline, which executes each command in a subshell. If the while-loop is executed in the subshell context, variable changes within are lost after the subshell terminates. Fortunately, Bash 4.2, released in 2011, supports the 'lastpipe' option, which makes the last element of a pipeline run in the current shell process. Switch to the pipeline with 'lastpipe' solution, and also set 'pipefail' to catch errors from ${NM}. Add the bash requirement to Documentation/process/changes.rst. Fixes: 31cb50b5590f ("kbuild: check static EXPORT_SYMBOL* by script instead of modpost") Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: Michael Ellerman <mpe@ellerman.id.au> Reported-by: Wang Yugui <wangyugui@e16-tech.com> Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Tested-by: Jon Hunter <jonathanh@nvidia.com> Acked-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64) Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Diffstat (limited to 'scripts')
-rwxr-xr-xscripts/check-local-export36
1 files changed, 21 insertions, 15 deletions
diff --git a/scripts/check-local-export b/scripts/check-local-export
index da745e2743b7..6ccc2f467416 100755
--- a/scripts/check-local-export
+++ b/scripts/check-local-export
@@ -8,11 +8,31 @@
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
+# hand-crafted error message here.
+#
+# 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} |
+
+{ ${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.
@@ -37,21 +57,7 @@ do
if [[ ${name} == __ksymtab_* ]]; then
export_symbols+=(${name#__ksymtab_})
fi
-
- # If there is no symbol in the object, ${NM} (both GNU nm and llvm-nm)
- # shows 'no symbols' diagnostic (but exits with 0). It is harmless and
- # hidden by '2>/dev/null'. However, it suppresses real error messages
- # as well. Add a hand-crafted error message here.
- #
- # Use --quiet instead of 2>/dev/null when we upgrade the minimum version
- # of binutils to 2.37, llvm to 13.0.0.
- #
- # Then, the following line will be really simple:
- # done < <(${NM} --quiet ${1})
-done < <(${NM} ${1} 2>/dev/null || { echo "${0}: ${NM} failed" >&2; false; } )
-
-# Catch error in the process substitution
-wait $!
+done
for name in "${export_symbols[@]}"
do