linux-kernel - Re: [PATCH] tracing: Fix trace_preempt_{on,off} for !CONFIG_DEBUG

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Date:   Mon, 4 Dec 2017 06:26:02 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Patrick Bellasi <patrick.bellasi@....com>
Cc:     linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Joel Fernandes <joelaf@...gle.com>
Subject: Re: [PATCH] tracing: Fix trace_preempt_{on,off} for
 !CONFIG_DEBUG_PREEMPT builds

On Mon,  4 Dec 2017 09:46:42 +0000
Patrick Bellasi <patrick.bellasi@....com> wrote:

> The new preempt enable/disable events introduced by:
> 
>  d59158162 tracing: Add support for preempt and irq enable/disable events
> 
> are defined only for CONFIG_DEBUG_PREEMPT kernels when the
> CONFIG_PREEMPTIRQ_EVENTS support, introduced by the above patch, is
> enabled.
> 
> These events are generated within by trace_preempt_{on,off} calls,
> which are part of the the "Preemption-off Latency Tracer"
> (CONFIG_PREEMPT_TRACER).
> 
> Currently these calls are (correctly) generated on CONFIG_PREEMPT_TRACER
> even when the kernel is !CONFIG_DEBUG_PREEMPT configured. Thus leading
> to an undefined reference to the new trace events.
> 
> Let's ensure that we always have an (eventually) empty definition of the
> events for CONFIG_PREEMPTIRQ_EVENTS kernels.
> 
> This patch will ensure that the additional preempt enabled/disable
> events are generated only when we have both:
>  CONFIG_PREEMPT_TRACER && CONFIG_DEBUG_PREEMPT
> 
> Signed-off-by: Patrick Bellasi <patrick.bellasi@....com>

Thanks, but you're the third person to send me a fix for this. I have
the first fixed applied to my code based off of 4.14-rc1 but that
branch breaks my tests. I was waiting for rc2 to come out (which just
happened), to rebase on and run my tests. I'll do that now.

Thanks,

-- Steve