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Date: Sun, 10 Dec 2023 09:26:13 -0500
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Subject: Re: [PATCH 14/14] ringbuffer/selftest: Add basic selftest to test
 chaning subbuf order
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To: Steven Rostedt <rostedt@goodmis.org>, linux-kernel@vger.kernel.org,
 linux-trace-kernel@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
 Mark Rutland <mark.rutland@arm.com>,
 Andrew Morton <akpm@linux-foundation.org>,
 Tzvetomir Stoyanov <tz.stoyanov@gmail.com>,
 Vincent Donnefort <vdonnefort@google.com>,
 Kent Overstreet <kent.overstreet@gmail.com>
References: <20231210035404.053677508@goodmis.org>
 <20231210040452.274868572@goodmis.org>
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
In-Reply-To: <20231210040452.274868572@goodmis.org>
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On 2023-12-09 22:54, Steven Rostedt wrote:
[...]
> +get_buffer_data_size() {
> +	sed -ne 's/^.*data.*size:\([0-9][0-9]*\).*/\1/p' events/header_page
> +}
> +
> +a="1234567890"
> +
> +make_str() {
> +        cnt=$1
> +        s=""
> +        while [ $cnt -gt 10 ]; do
> +                s="${s}${a}"
> +                cnt=$((cnt-10))
> +        done
> +        while [ $cnt -gt 0 ]; do
> +                s="${s}X"
> +                cnt=$((cnt-1))
> +        done
> +        echo -n $s
> +}
> +
> +test_buffer() {
> +
> +	size=`get_buffer_data_size`
> +
> +	str=`make_str $size`
> +
> +	echo $str > trace_marker
> +
> +	grep -q $a trace

This test has no clue if the record was truncated or not.

It basically repeats the string

"1234567890" until it fills the subbuffer size and pads with
XXXX as needed as trace marker payload, but the grep looks for the
"1234567890" pattern only.

The test should be extended to validate whether the trace marker
payload was truncated or not, otherwise it is of limited value.

Thanks,

Mathieu


-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com