linux-kernel - Re: [4.4-rt PATCH] trace: use rcuidle version for preemptoff

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Date:	Mon, 7 Mar 2016 19:00:09 +0100
From:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:	Yang Shi <yang.shi@...driver.com>
Cc:	tglx@...utronix.de, rostedt@...dmis.org,
	linux-kernel@...r.kernel.org, linux-rt-users@...r.kernel.org
Subject: Re: [4.4-rt PATCH] trace: use rcuidle version for preemptoff_hist
 trace point

* Yang Shi | 2016-02-23 13:23:23 [-0800]:

>I recall the rcuidle version is used by 4.1-rt, but not sure why it is dropped
>in 4.4-rt. It looks such fix is still needed. 

I don't recall while I removed it. It was durring v4.1 -> v4.4 port. In
v4.1 we had the idle version only in time_hardirqs_on() + …_off(). You
introduced it also to start_critical_timings() + stop_…(). Is this
required?
In the meantime I bring back the empty macro of
trace_preemptirqsoff_hist_rcuidle() back in -RT sine it breaks compile
latest v4.4.3-RT9

> kernel/trace/trace_irqsoff.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
>diff --git a/kernel/trace/trace_irqsoff.c b/kernel/trace/trace_irqsoff.c
>index 36e584f..069942c 100644
>--- a/kernel/trace/trace_irqsoff.c
>+++ b/kernel/trace/trace_irqsoff.c
>@@ -421,13 +421,13 @@ void start_critical_timings(void)
> {
> 	if (preempt_trace() || irq_trace())
> 		start_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
>-	trace_preemptirqsoff_hist(TRACE_START, 1);
>+	trace_preemptirqsoff_hist_rcuidle(TRACE_START, 1);
> }
> EXPORT_SYMBOL_GPL(start_critical_timings);
> 
> void stop_critical_timings(void)
> {
>-	trace_preemptirqsoff_hist(TRACE_STOP, 0);
>+	trace_preemptirqsoff_hist_rcuidle(TRACE_STOP, 0);
> 	if (preempt_trace() || irq_trace())
> 		stop_critical_timing(CALLER_ADDR0, CALLER_ADDR1);
> }

Sebastian