Re: [PATCH V3 8/9] tracing: Add osnoise tracer

[Steven Rostedt <rostedt@goodmis.org>]

On Tue, 8 Jun 2021 19:17:55 +0200
Daniel Bristot de Oliveira <bristot@redhat.com> wrote:

> 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?
>

Or perhaps have that pr_err() actually be written into the trace buffer?

You can use

	trace_array_printk_buf(tr->array_buffer.buffer, _THIS_IP_, "string");

without it triggering that nasty trace_printk() notice ;-)

-- Steve