linux-kernel - Re: [PATCH v3] tracing/selftests: Add test to test the trace

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Message-ID: <CAJ1xhMXuxGHfD8oRfbna_drpHmNv0RUXFrvuVv6rtt-KeCM9fQ@mail.gmail.com>
Date:   Wed, 13 Dec 2023 10:09:50 +0200
From:   Alexander Kapshuk <alexander.kapshuk@...il.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Linux Trace Kernel <linux-trace-kernel@...r.kernel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Shuah Khan <shuah@...nel.org>, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v3] tracing/selftests: Add test to test the trace_marker

The REs used in the sed commands below may be simplified as shown if desired.

On Wed, Dec 13, 2023 at 2:22 AM Steven Rostedt <rostedt@...dmis.org> wrote:
>
> From: "Steven Rostedt (Google)" <rostedt@...dmis.org>
>
> Add a test that writes longs strings, some over the size of the sub buffer
> and make sure that the entire content is there.
>
> Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
> ---
> Changes since v2: https://lore.kernel.org/linux-trace-kernel/20231212151632.25c9b67d@gandalf.local.home
>
> - Realized with the upcoming change of the dynamic subbuffer sizes, that
>   this test will fail if the subbuffer is bigger than what the trace_seq
>   can hold. Now the trace_marker does not always utilize the full subbuffer
>   but the size of the trace_seq instead. As that size isn't available to
>   user space, we can only just make sure all content is there.
>
>  .../ftrace/test.d/00basic/trace_marker.tc     | 82 +++++++++++++++++++
>  1 file changed, 82 insertions(+)
>  create mode 100755 tools/testing/selftests/ftrace/test.d/00basic/trace_marker.tc
>
> diff --git a/tools/testing/selftests/ftrace/test.d/00basic/trace_marker.tc b/tools/testing/selftests/ftrace/test.d/00basic/trace_marker.tc
> new file mode 100755
> index 000000000000..b24aff5807df
> --- /dev/null
> +++ b/tools/testing/selftests/ftrace/test.d/00basic/trace_marker.tc
> @@ -0,0 +1,82 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0
> +# description: Basic tests on writing to trace_marker
> +# requires: trace_marker
> +# flags: instance
> +
> +get_buffer_data_size() {
> +       sed -ne 's/^.*data.*size:\([0-9][0-9]*\).*/\1/p' events/header_page
            sed -n 's!.*data.*size:\([^;]*\).*!\1!p' events/header_page
> +}
> +
> +get_buffer_data_offset() {
> +       sed -ne 's/^.*data.*offset:\([0-9][0-9]*\).*/\1/p' events/header_page
            sed -n 's!.*data.*offset:\([^;]*\).*!\1!p' events/header_page
> +}
> +
> +get_event_header_size() {
> +       type_len=`sed -ne 's/^.*type_len.*:[^0-9]*\([0-9][0-9]*\).*/\1/p' events/header_event`
            type_len=`sed -n '/type_len.*bits/s![^0-9]*!!gp'
events/header_event`

> +       time_len=`sed -ne 's/^.*time_delta.*:[^0-9]*\([0-9][0-9]*\).*/\1/p' events/header_event`
            time_len=`sed -n '/time_delta/s![^0-9]*!!gp' events/header_event`

> +       array_len=`sed -ne 's/^.*array.*:[^0-9]*\([0-9][0-9]*\).*/\1/p' events/header_event`
            array_len=`sed -n '/array/s![^0-9]*!!gp' events/header_event`

> +       total_bits=$((type_len+time_len+array_len))
> +       total_bits=$((total_bits+7))
> +       echo $((total_bits/8))
> +}
> +
> +get_print_event_buf_offset() {
> +       sed -ne 's/^.*buf.*offset:\([0-9][0-9]*\).*/\1/p' events/ftrace/print/format
            sed -n 's!.*buf.*offset:\([^;]*\).*!\1!p' events/ftrace/print/format
> +}
> +
> +event_header_size=`get_event_header_size`
> +print_header_size=`get_print_event_buf_offset`
> +
> +data_offset=`get_buffer_data_offset`
> +
> +marker_meta=$((event_header_size+print_header_size))
> +
> +make_str() {
> +        cnt=$1
> +       # subtract two for \n\0 as marker adds these
> +       cnt=$((cnt-2))
> +       printf -- 'X%.0s' $(seq $cnt)
> +}
> +
> +write_buffer() {
> +       size=$1
> +
> +       str=`make_str $size`
> +
> +       # clear the buffer
> +       echo > trace
> +
> +       # write the string into the marker
> +       echo -n $str > trace_marker
> +
> +       echo $str
> +}
> +
> +test_buffer() {
> +
> +       size=`get_buffer_data_size`
> +       oneline_size=$((size-marker_meta))
> +       echo size = $size
> +       echo meta size = $marker_meta
> +
> +       # Now add a little more the meta data overhead will overflow
> +
> +       str=`write_buffer $size`
> +
> +       # Make sure the line was broken
> +       new_str=`awk ' /tracing_mark_write:/ { sub(/^.*tracing_mark_write: /,"");printf "%s", $0; exit}' trace`
> +
> +       if [ "$new_str" = "$str" ]; then
> +               exit fail;
> +       fi
> +
> +       # Make sure the entire line can be found
> +       new_str=`awk ' /tracing_mark_write:/ { sub(/^.*tracing_mark_write: */,"");printf "%s", $0; }' trace`
> +
> +       if [ "$new_str" != "$str" ]; then
> +               exit fail;
> +       fi
> +}
> +
> +test_buffer
> --
> 2.42.0
>