linux-kernel - Re: [PATCH v5 3/3] tracing/selftests: Add tests for hist trigger expression parsing

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Date:   Thu, 28 Oct 2021 07:12:26 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Kalesh Singh <kaleshsingh@...gle.com>
Cc:     surenb@...gle.com, hridya@...gle.com, namhyung@...nel.org,
        kernel-team@...roid.com, rostedt@...dmis.org, mhiramat@...nel.org,
        Ingo Molnar <mingo@...hat.com>, Shuah Khan <shuah@...nel.org>,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v5 3/3] tracing/selftests: Add tests for hist trigger
 expression parsing

On Wed, 27 Oct 2021 13:59:10 -0700
Kalesh Singh <kaleshsingh@...gle.com> wrote:

> Add tests for the parsing of hist trigger expressions; and to
> validate expression evaluation.
> 
> Signed-off-by: Kalesh Singh <kaleshsingh@...gle.com>

This looks good to me :)

Acked-by: Masami Hiramatsu <mhiramat@...nel.org>

Thanks!

> ---
> Changes in v5:
>   - Add README pattern to requires tag, per Masami
> 
> Changes in v3:
>   - Remove .sym-offset error check tests
> 
> Changes in v2:
>   - Add Namhyung's Reviewed-by
>   - Update comment to clarify err_pos in "Too many subexpressions" test
> 
>  .../trigger/trigger-hist-expressions.tc       | 72 +++++++++++++++++++
>  1 file changed, 72 insertions(+)
>  create mode 100644 tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-expressions.tc
> 
> diff --git a/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-expressions.tc b/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-expressions.tc
> new file mode 100644
> index 000000000000..9690f9f809e7
> --- /dev/null
> +++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-expressions.tc
> @@ -0,0 +1,72 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0
> +# description: event trigger - test histogram expression parsing
> +# requires: set_event events/sched/sched_process_fork/trigger events/sched/sched_process_fork/hist error_log "<var1>=<field|var_ref|numeric_literal>":README
> +
> +
> +fail() { #msg
> +    echo $1
> +    exit_fail
> +}
> +
> +get_hist_var() { #var_name hist_path
> +    hist_output=`grep -m1 "$1: " $2`
> +    hitcount=`echo $hist_output | awk '{ for (i=1; i<=NF; ++i) { if ($i ~ "hitcount:") print $(i+1)} }'`
> +    var_sum=`echo $hist_output | awk '{ for (i=1; i<=NF; ++i) { if ($i ~ "'$1':") print $(i+1)} }'`
> +    var_val=$(( var_sum / hitcount ))
> +    echo $var_val
> +}
> +
> +test_hist_expr() { # test_name expression expected_val
> +    reset_trigger
> +
> +    echo "Test hist trigger expressions - $1"
> +
> +    echo "hist:keys=common_pid:x=$2" > events/sched/sched_process_fork/trigger
> +    echo 'hist:keys=common_pid:vals=$x' >> events/sched/sched_process_fork/trigger
> +    for i in `seq 1 10` ; do ( echo "forked" > /dev/null); done
> +
> +    actual=`get_hist_var x events/sched/sched_process_fork/hist`
> +
> +    if [ $actual != $3 ]; then
> +        fail "Failed hist trigger expression evaluation: Expression: $2 Expected: $3, Actual: $actual"
> +    fi
> +
> +    reset_trigger
> +}
> +
> +check_error() { # test_name command-with-error-pos-by-^
> +    reset_trigger
> +
> +    echo "Test hist trigger expressions - $1"
> +    ftrace_errlog_check 'hist:sched:sched_process_fork' "$2" 'events/sched/sched_process_fork/trigger'
> +
> +    reset_trigger
> +}
> +
> +test_hist_expr "Variable assignment" "123" "123"
> +
> +test_hist_expr "Subtraction not associative" "16-8-4-2" "2"
> +
> +test_hist_expr "Division not associative" "64/8/4/2" "1"
> +
> +test_hist_expr "Same precedence operators (+,-) evaluated left to right" "16-8+4+2" "14"
> +
> +test_hist_expr "Same precedence operators (*,/) evaluated left to right" "4*3/2*2" "12"
> +
> +test_hist_expr "Multiplication evaluated before addition/subtraction" "4+3*2-2" "8"
> +
> +test_hist_expr "Division evaluated before addition/subtraction" "4+6/2-2" "5"
> +
> +# Division by zero returns -1
> +test_hist_expr "Handles division by zero" "3/0" "-1"
> +
> +# err pos for "too many subexpressions" is dependent on where
> +# the last subexpression was detected. This can vary depending
> +# on how the expression tree was generated.
> +check_error "Too many subexpressions" 'hist:keys=common_pid:x=32+^10*3/20-4'
> +check_error "Too many subexpressions" 'hist:keys=common_pid:x=^1+2+3+4+5'
> +
> +check_error "Unary minus not supported in subexpression" 'hist:keys=common_pid:x=-(^1)+2'
> +
> +exit 0
> -- 
> 2.33.0.1079.g6e70778dc9-goog
> 


-- 
Masami Hiramatsu <mhiramat@...nel.org>