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Date:   Fri, 8 Jul 2022 16:39:47 +0200
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Subject: Re: [PATCH V4 01/20] rv: Add Runtime Verification (RV) interface
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To:     Tao Zhou <tao.zhou@linux.dev>, Steven Rostedt <rostedt@goodmis.org>
Cc:     Wim Van Sebroeck <wim@linux-watchdog.org>,
        Guenter Roeck <linux@roeck-us.net>,
        Jonathan Corbet <corbet@lwn.net>,
        Ingo Molnar <mingo@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Will Deacon <will@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Marco Elver <elver@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Shuah Khan <skhan@linuxfoundation.org>,
        Gabriele Paoloni <gpaoloni@redhat.com>,
        Juri Lelli <juri.lelli@redhat.com>,
        Clark Williams <williams@redhat.com>,
        linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-trace-devel@vger.kernel.org
References: <cover.1655368610.git.bristot@kernel.org>
 <60548902dbccaa7ba420e40e46835693e27f643f.1655368610.git.bristot@kernel.org>
 <YsXLDvjHqOxYtckg@geo.homenetwork>
From:   Daniel Bristot de Oliveira <bristot@kernel.org>
In-Reply-To: <YsXLDvjHqOxYtckg@geo.homenetwork>
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Hey Tao!

On 7/6/22 19:49, Tao Zhou wrote:
>> +static void *enabled_monitors_start(struct seq_file *m, loff_t *pos)
>> +{
>> +	struct rv_monitor_def *m_def;
>> +	loff_t l;
>> +
>> +	mutex_lock(&rv_interface_lock);
>> +	m_def = list_entry(&rv_monitors_list, struct rv_monitor_def, list);
> I realized this m_def is not real but vain. Is it possible the loop is
> skiped and just return m_def that is not valid.

that is empty... not a problem.

I am not seeing (the possible) problem here. Could you simulate/reproduce the problem?

Btw, this code is "inspired" (iow stolen) from trace_events.c.

Am I missing something? steve?

>> +	for (l = 0; l <= *pos; ) {
>> +		m_def = enabled_monitors_next(m, m_def, &l);
>> +		if (!m_def)
>> +			break;
>> +	}
>> +
>> +	return m_def;
>> +}

-- Daniel