Re: [PATCH 2/2] perf tests: add test for trace output loss

[Arnaldo Carvalho de Melo <acme@kernel.org>]

On Wed, Nov 06, 2024 at 11:45:18PM +0000, Benjamin Peterson wrote:
> Add a test that checks that trace output is not lost to races. This is
> accomplished by tracing the exit_group syscall of "true" multiple times and
> checking for correct output.
> 
> Conveniently, this test also serves as a regression test for 5fb8e56542a3 ("perf
> trace: avoid garbage when not printing a trace event's arguments") because
> exit_group triggers the previously buggy printing behavior.
> 
> Signed-off-by: Benjamin Peterson <benjamin@engflow.com>
> ---
>  tools/perf/tests/shell/trace_exit_race.sh | 31 +++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
>  create mode 100755 tools/perf/tests/shell/trace_exit_race.sh
> 
> diff --git a/tools/perf/tests/shell/trace_exit_race.sh b/tools/perf/tests/shell/trace_exit_race.sh
> new file mode 100755
> index 000000000000..8b70324bc5b4
> --- /dev/null
> +++ b/tools/perf/tests/shell/trace_exit_race.sh
> @@ -0,0 +1,31 @@
> +#!/bin/sh
> +# perf trace exit race
> +# SPDX-License-Identifier: GPL-2.0
> +
> +# Check that the last events of a perf trace'd subprocess are not
> +# lost. Specifically, trace the exiting syscall of "true" 100 times and ensure
> +# the output contains 100 correct lines.
> +
> +# shellcheck source=lib/probe.sh
> +. "$(dirname $0)"/lib/probe.sh
> +
> +skip_if_no_perf_trace || exit 2
> +
> +trace_shutdown_race() {
> +	for i in $(seq 100); do
> +		perf trace -e syscalls:sys_enter_exit_group true 2>>$file
> +	done
> +	[ $(grep -c -E " +[0-9]+\.[0-9]+ +true/[0-9]+ syscalls:sys_enter_exit_group\(\)$" $file) = "100" ]
> +}
> +
> +
> +file=$(mktemp /tmp/temporary_file.XXXXX)
> +
> +# Do not use whatever ~/.perfconfig file, it may change the output
> +# via trace.{show_timestamp,show_prefix,etc}
> +export PERF_CONFIG=/dev/null
> +
> +trace_shutdown_race
> +err=$?
> +rm -f ${file}
> +exit $err
> -- 

Its failing with shellcheck, I'm trying to fix it:

  CC      /tmp/build/perf-tools-next/builtin-trace.o
  TEST    /tmp/build/perf-tools-next/tests/shell/trace_exit_race.sh.shellcheck_log

In tests/shell/trace_exit_race.sh line 15:
	for i in $(seq 100); do
        ^-^ SC2034 (warning): i appears unused. Verify use (or export if used externally).


In tests/shell/trace_exit_race.sh line 18:
	[ $(grep -c -E " +[0-9]+\.[0-9]+ +true/[0-9]+ syscalls:sys_enter_exit_group\(\)$" $file) = "100" ]
          ^-- SC2046 (warning): Quote this to prevent word splitting.

For more information:
  https://www.shellcheck.net/wiki/SC2034 -- i appears unused. Verify use (or ...
  https://www.shellcheck.net/wiki/SC2046 -- Quote this to prevent word splitt...
make[4]: *** [tests/Build:91: /tmp/build/perf-tools-next/tests/shell/trace_exit_race.sh.shellcheck_log] Error 1
make[3]: *** [/home/acme/git/perf-tools-next/tools/build/Makefile.build:158: tests] Error 2
make[2]: *** [Makefile.perf:777: /tmp/build/perf-tools-next/perf-test-in.o] Error 2
make[2]: *** Waiting for unfinished jobs....