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Subject: Re: [PATCH V3 8/9] tracing: Add osnoise tracer
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     linux-kernel@vger.kernel.org, Phil Auld <pauld@redhat.com>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Kate Carcia <kcarcia@redhat.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Alexandre Chartre <alexandre.chartre@oracle.com>,
        Clark Willaims <williams@redhat.com>,
        John Kacur <jkacur@redhat.com>,
        Juri Lelli <juri.lelli@redhat.com>, linux-doc@vger.kernel.org
References: <cover.1621024265.git.bristot@redhat.com>
 <bd09a2be9cd0cecee86374dbb49235dd2ef9d750.1621024265.git.bristot@redhat.com>
 <20210604172803.527aa070@oasis.local.home>
From:   Daniel Bristot de Oliveira <bristot@redhat.com>
Message-ID: <abf38ca3-3c14-c00a-ff74-f1a75e3ec2e5@redhat.com>
Date:   Tue, 8 Jun 2021 19:17:55 +0200
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On 6/4/21 11:28 PM, Steven Rostedt wrote:
>> +	/*
>> +	 * This is an evidence of race conditions that cause
>> +	 * a value to be "discounted" too much.
>> +	 */
>> +	if (duration < 0)
>> +		pr_err("int safe negative!\n");
> Probably want to have this happen at most once a run. If something were
> to break, I don't think we want this to live lock the machine doing
> tons of prints. We could have a variable stored on the
> osnoise_variables that states this was printed. Check that variable to
> see if it wasn't printed during a run (when current_tracer was set),
> and print only once if it is.

I created a "bool tainted" variable, that is set true if any problem with time()
related functions happen. I will pr_warn that there is a problem on _start(),
but also print this info at the top of the tracer header, so it is clear also
from the trace output.

Thoughts?

-- Daniel