Re: [PATCH] tracing: always define trace_{irq,preempt}_{enable_disable}

From: Joel Fernandes <joelaf@google.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] tracing: always define trace_{irq,preempt}_{enable_disable}
Date: Thu, 19 Oct 2017 08:42:28 -0700	[thread overview]
Message-ID: <CAJWu+oqZdsA68Cs0CGF4ixULtWcsEkrhoe7oSTbZDf5wb8TDSw@mail.gmail.com> (raw)
In-Reply-To: <20171019083230.2450779-1-arnd@arndb.de>

Hi Arnd,

On Thu, Oct 19, 2017 at 1:32 AM, Arnd Bergmann <arnd@arndb.de> wrote:
> We get a build error in the irqsoff tracer in some configurations:
>
> kernel/trace/trace_irqsoff.c: In function 'trace_preempt_on':
> kernel/trace/trace_irqsoff.c:855:2: error: implicit declaration of function 'trace_preempt_enable_rcuidle'; did you mean 'trace_irq_enable_rcuidle'? [-Werror=implicit-function-declaration]
>   trace_preempt_enable_rcuidle(a0, a1);
>
> The problem is that trace_preempt_enable_rcuidle() has different
> definition based on multiple Kconfig symbols, but not all combinations
> have a valid definition.
>
> This changes the conditions so that we always get exactly one
> definition of each of the four tracing macros. I have not tried
> to verify that these definitions are sensible, but now we
> can build all randconfig combinations again.
>

Thanks for catching this. I didn't follow why it breaks for you,
especially I'm troubled by your proposal of defining the empty macro
for !defined(CONFIG_DEBUG_PREEMPT) in your patch. Could you provide
your config sample and architecture you're building for? I'm guessing
its ARM but let me know. I will try to build it and reproduce it.

thanks,
Joel