On Fri, 16 Feb 2024 15:26:26 +0530
Naveen N Rao <nav...@kernel.org> wrote:
> Add a test to exercize cpu hotplug with the function tracer active to
> ensure that sensitive functions in idle path are excluded from being
> traced. This helps catch issues such as the one fixed by commit
> 4b3338aaa74d ("powerpc/ftrace: Fix stack teardown in ftrace_no_trace").
>
> Signed-off-by: Naveen N Rao <nav...@kernel.org>
> Acked-by: Masami Hiramatsu (Google) <mhira...@kernel.org>
Acked-by: Steven Rostedt (Google) <rost...@goodmis.org>
Shuah, can you take this?
Thanks,
-- Steve
> ---
> .../ftrace/test.d/ftrace/func_hotplug.tc | 42 +++++++++++++++++++
> 1 file changed, 42 insertions(+)
> create mode 100644
> tools/testing/selftests/ftrace/test.d/ftrace/func_hotplug.tc
>
> diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/func_hotplug.tc
> b/tools/testing/selftests/ftrace/test.d/ftrace/func_hotplug.tc
> new file mode 100644
> index 000000000000..ccfbfde3d942
> --- /dev/null
> +++ b/tools/testing/selftests/ftrace/test.d/ftrace/func_hotplug.tc
> @@ -0,0 +1,42 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0-or-later
> +# description: ftrace - function trace across cpu hotplug
> +# requires: function:tracer
> +
> +if ! which nproc ; then
> + nproc() {
> + ls -d /sys/devices/system/cpu/cpu[0-9]* | wc -l
> + }
> +fi
> +
> +NP=`nproc`
> +
> +if [ $NP -eq 1 ] ;then
> + echo "We cannot test cpu hotplug in UP environment"
> + exit_unresolved
> +fi
> +
> +# Find online cpu
> +for i in /sys/devices/system/cpu/cpu[1-9]*; do
> + if [ -f $i/online ] && [ "$(cat $i/online)" = "1" ]; then
> + cpu=$i
> + break
> + fi
> +done
> +
> +if [ -z "$cpu" ]; then
> + echo "We cannot test cpu hotplug with a single cpu online"
> + exit_unresolved
> +fi
> +
> +echo 0 > tracing_on
> +echo > trace
> +
> +: "Set $(basename $cpu) offline/online with function tracer enabled"
> +echo function > current_tracer
> +echo 1 > tracing_on
> +(echo 0 > $cpu/online)
> +(echo "forked"; sleep 1)
> +(echo 1 > $cpu/online)
> +echo 0 > tracing_on
> +echo nop > current_tracer
>
> base-commit: 130a83879954a9fed35cf4474d223b4fcfd479fa
