Re: [PATCH v6 12/24] tracing: selftests: Add trace remote tests

Masami Hiramatsu
2025-09-03T04:58:18Z

On Thu, 21 Aug 2025 09:14:00 +0100
Vincent Donnefort <vdonnefort@google.com> wrote:

> Exercise the tracefs interface for trace remote with a set of tests to
> check:
>
> * loading/unloading (unloading.tc)
> * reset (reset.tc)
> * size changes (buffer_size.tc)
> * event integrity (trace_pipe)
>
> Cc: Shuah Khan <skhan@linuxfoundation.org>
> Cc: linux-kselftest@vger.kernel.org
> Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
>
> diff --git a/tools/testing/selftests/ftrace/test.d/remotes/buffer_size.tc b/tools/testing/selftests/ftrace/test.d/remotes/buffer_size.tc
> new file mode 100644
> index 000000000000..60bf431ccc91
> --- /dev/null
> +++ b/tools/testing/selftests/ftrace/test.d/remotes/buffer_size.tc
> @@ -0,0 +1,24 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0
> +# description: Test trace remote buffer size

I think this test requires `remotes/`. If so, please add

# requires: remotes

Then this test will be skipped if it is not enabled.

> +
> +. $TEST_DIR/remotes/functions
> +
> +test_buffer_size()
> +{
> + echo 0 > tracing_on
> + assert_unloaded
> +
> + echo 4096 > buffer_size_kb
> + echo 1 > tracing_on
> + assert_loaded
> +
> + echo 0 > tracing_on
> + echo 7 > buffer_size_kb
> +}
> +
> +if [ -z "$SOURCE_REMOTE_TEST" ]; then
> + set -e
> + setup_remote_test
> + test_buffer_size
> +fi
> diff --git a/tools/testing/selftests/ftrace/test.d/remotes/functions b/tools/testing/selftests/ftrace/test.d/remotes/functions
> new file mode 100644
> index 000000000000..504a495b3b1b
> --- /dev/null
> +++ b/tools/testing/selftests/ftrace/test.d/remotes/functions
> @@ -0,0 +1,33 @@
> +# SPDX-License-Identifier: GPL-2.0
> +
> +setup_remote()
> +{
> + local name=$1
> +
> + [ -e $TRACING_DIR/remotes/$name/write_event ] || exit_unresolved
> +
> + cd remotes/$name/
> + echo 0 > tracing_on
> + clear_trace
> + echo 7 > buffer_size_kb
> + echo 0 > events/enable
> + echo 1 > events/$name/selftest/enable
> + echo 1 > tracing_on
> +}
> +
> +setup_remote_test()
> +{
> + [ -d $TRACING_DIR/remotes/test/ ] || modprobe remote_test || exit_unresolved
> +
> + setup_remote "test"
> +}
> +
> +assert_loaded()
> +{
> + grep -q "(loaded)" buffer_size_kb
> +}
> +
> +assert_unloaded()
> +{
> + grep -q "(unloaded)" buffer_size_kb
> +}
> diff --git a/tools/testing/selftests/ftrace/test.d/remotes/reset.tc b/tools/testing/selftests/ftrace/test.d/remotes/reset.tc
> new file mode 100644
> index 000000000000..93d6eb2a807f
> --- /dev/null
> +++ b/tools/testing/selftests/ftrace/test.d/remotes/reset.tc
> @@ -0,0 +1,105 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0
> +# description: Test trace remote reset

Ditto.

> +
> +. $TEST_DIR/remotes/functions
> +
> +get_cpu_ids()
> +{
> + sed -n 's/^processor\s*:\s*\([0-9]\+\).*/\1/p' /proc/cpuinfo
> +}
> +
> +dump_trace()
> +{
> + output=$(mktemp /tmp/remote_test.XXXXXX)

For the test-local temporary working directory, can you use $TMPDIR
instead of /tmp ? That directory is removed after running each test.

> + cat trace_pipe > $output &
> + pid=$!
> + sleep 1
> + kill -1 $pid
> +
> + echo $output
> +}
> +
> +check_reset()
> +{
> + write_event_path="write_event"
> + taskset=""
> +
> + clear_trace
> +
> + # Is the buffer empty?
> + output=$(dump_trace)
> + test $(wc -l $output | cut -d ' ' -f1) -eq 0
> +
> + if $(echo $(pwd) | grep -q "per_cpu/cpu"); then
> + write_event_path="../../write_event"
> + cpu_id=$(echo $(pwd) | sed -e 's/.*per_cpu\/cpu//')
> + taskset="taskset -c $cpu_id"
> + fi
> + rm $output
> +
> + # Can we properly write a new event?
> + $taskset echo 7890 > $write_event_path
> + output=$(dump_trace)
> + test $(wc -l $output | cut -d ' ' -f1) -eq 1
> + grep -q "id=7890" $output
> + rm $output
> +}
> +
> +test_global_interface()
> +{
> + output=$(mktemp /tmp/remote_test.XXXXXX)
> +
> + # Confidence check
> + echo 123456 > write_event
> + output=$(dump_trace)
> + grep -q "id=123456" $output
> + rm $output
> +
> + # Reset single event
> + echo 1 > write_event
> + check_reset
> +
> + # Reset lost events
> + for i in $(seq 1 10000); do
> + echo 1 > write_event
> + done
> + check_reset
> +}
> +
> +test_percpu_interface()
> +{
> + [ "$(get_cpu_ids | wc -l)" -ge 2 ] || return 0
> +
> + for cpu in $(get_cpu_ids); do
> + taskset -c $cpu echo 1 > write_event
> + done
> +
> + check_non_empty=0
> + for cpu in $(get_cpu_ids); do
> + cd per_cpu/cpu$cpu/
> +
> + if [ $check_non_empty -eq 0 ]; then
> + check_reset
> + check_non_empty=1
> + else
> + # Check we have only reset 1 CPU
> + output=$(dump_trace)
> + test $(wc -l $output | cut -d ' ' -f1) -eq 1
> + rm $output
> + fi
> + cd -
> + done
> +}
> +
> +test_reset()
> +{
> + test_global_interface
> + test_percpu_interface
> +}
> +
> +if [ -z "$SOURCE_REMOTE_TEST" ]; then
> + set -e
> + setup_remote_test
> + test_reset
> +fi
> diff --git a/tools/testing/selftests/ftrace/test.d/remotes/trace_pipe.tc b/tools/testing/selftests/ftrace/test.d/remotes/trace_pipe.tc
> new file mode 100644
> index 000000000000..f4bd2b3655e0
> --- /dev/null
> +++ b/tools/testing/selftests/ftrace/test.d/remotes/trace_pipe.tc
> @@ -0,0 +1,57 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0
> +# description: Test trace remote trace_pipe

Ditto.

> +
> +. $TEST_DIR/remotes/functions
> +
> +test_trace_pipe()
> +{
> + echo 0 > tracing_on
> + assert_unloaded
> +
> + echo 1024 > buffer_size_kb
> + echo 1 > tracing_on
> + assert_loaded
> +
> + output=$(mktemp /tmp/remote_test.XXXXXX)
> +
> + cat trace_pipe > $output &
> + pid=$!
> +
> + for i in $(seq 1 1000); do
> + echo $i > write_event
> + done
> +
> + echo 0 > tracing_on
> + sleep 1
> + kill $pid
> +
> + prev_ts=0 # TODO: Init with proper clock value
> + prev_id=0
> +
> + # Only keep <timestamp> <id>
> + sed -i -e 's/\[[0-9]*\]\s*\([0-9]*.[0-9]*\): [a-z]* id=\([0-9]*\)/\1 \2/' $output
> +
> + IFS=$'\n'

This fails checkbashisms test. Can you use printf for this?

IFS=$(printf "\n")

> + for line in $(cat $output); do
> + ts=$(echo $line | cut -d ' ' -f 1)
> + id=$(echo $line | cut -d ' ' -f 2)
> +
> + test $(echo "$ts>$prev_ts" | bc) -eq 1
> + test $id -eq $((prev_id + 1))
> +
> + prev_ts=$ts
> + prev_id=$id
> + done
> +
> + test $prev_id -eq 1000
> +
> + rm $output
> +}
> +
> +if [ -z "$SOURCE_REMOTE_TEST" ]; then
> + set -e
> +
> + setup_remote_test
> + test_trace_pipe
> +fi
> diff --git a/tools/testing/selftests/ftrace/test.d/remotes/unloading.tc b/tools/testing/selftests/ftrace/test.d/remotes/unloading.tc
> new file mode 100644
> index 000000000000..99f97e100fde
> --- /dev/null
> +++ b/tools/testing/selftests/ftrace/test.d/remotes/unloading.tc
> @@ -0,0 +1,40 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0
> +# description: Test trace remote unloading

Here, please add "requires: remotes" line.

Thank you,

--
Masami Hiramatsu (Google) <mhiramat@kernel.org>