Re: [FIX PATCH] selftests: tracing: Fix to unmount tracefs for recovering environment

Steven Rostedt
2023-09-11T20:55:06Z

On Sat, 9 Sep 2023 18:36:39 +0900
"Masami Hiramatsu (Google)" <mhiramat@kernel.org> wrote:

> From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
>
> Fix to unmount the tracefs if the ftracetest mounted it for recovering
> system environment. If the tracefs is already mounted, this does nothing.
>
> Suggested-by: Mark Brown <broonie@kernel.org>
> Link: https://lore.kernel.org/all/29fce076-746c-4650-8358-b4e0fa215cf7@sirena.org.uk/
> Fixes: cbd965bde74c ("ftrace/selftests: Return the skip code when tracing directory not configured in kernel")
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
> ---
> tools/testing/selftests/ftrace/ftracetest | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/tools/testing/selftests/ftrace/ftracetest b/tools/testing/selftests/ftrace/ftracetest
> index cb5f18c06593..89c212d82256 100755
> --- a/tools/testing/selftests/ftrace/ftracetest
> +++ b/tools/testing/selftests/ftrace/ftracetest
> @@ -31,6 +31,9 @@ err_ret=1
> # kselftest skip code is 4
> err_skip=4
>
> +# umount required
> +UMOUNT_DIR=""
> +
> # cgroup RT scheduling prevents chrt commands from succeeding, which
> # induces failures in test wakeup tests. Disable for the duration of
> # the tests.
> @@ -45,6 +48,9 @@ setup() {
>
> cleanup() {
> echo $sched_rt_runtime_orig > $sched_rt_runtime
> + if [ "${UMOUNT_DIR}" ]; then

Shouldn't the above be:

if [ ! -z "${UNMOUNT_DIR}" ]; then

?

-- Steve

> + umount ${UMOUNT_DIR} ||:
> + fi
> }
>
> errexit() { # message
> @@ -160,11 +166,13 @@ if [ -z "$TRACING_DIR" ]; then
> mount -t tracefs nodev /sys/kernel/tracing ||
> errexit "Failed to mount /sys/kernel/tracing"
> TRACING_DIR="/sys/kernel/tracing"
> + UMOUNT_DIR=${TRACING_DIR}
> # If debugfs exists, then so does /sys/kernel/debug
> elif [ -d "/sys/kernel/debug" ]; then
> mount -t debugfs nodev /sys/kernel/debug ||
> errexit "Failed to mount /sys/kernel/debug"
> TRACING_DIR="/sys/kernel/debug/tracing"
> + UMOUNT_DIR=${TRACING_DIR}
> else
> err_ret=$err_skip
> errexit "debugfs and tracefs are not configured in this kernel"