On Tue, 4 Apr 2017 01:27:25 -0700
Joel Fernandes <joelaf@xxxxxxxxxx> wrote:
> Hi Steven,
>
> Just looking at code of the preemptirqsoff tracer, I wonder if it is
> really working as expected.
>
> With the tracer enabled, start_critical_timing will be called only if
> _both_ preemption and IRQs are turned off. Instead shouldn't this be
> an OR condition (either preemption or IRQs are turned off)?
What code are you looking at. From what I have:
void start_critical_timings(void)
{
if (preempt_trace() || irq_trace())
start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
}
There's an OR statement.
-- Steve
>
> >From the example in ftrace.txt documentation:
> local_irq_disable();
> call_function_with_irqs_off();
> preempt_disable();
> call_function_with_irqs_and_preemption_off();
> local_irq_enable();
> call_function_with_preemption_off();
> preempt_enable();
>
> Looks to me like the preemptirqsoff tracer will starting tracing from
> preempt_disable and end at the preempt_enable. Instead, shouldn't we
> be tracing starting from the local_irq_disable and end at the
> preempt_enable?
>
> Regards,
> Joel
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