Re: [PATCH 1/2] tracepoints: Add helper to test if tracepoint is enabled in a header

From: Steven Rostedt <rostedt@goodmis.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
	Yafang Shao <laoar.shao@gmail.com>,
	Axel Rasmussen <axelrasmussen@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	Michel Lespinasse <walken@google.com>,
	Daniel Jordan <daniel.m.jordan@oracle.com>,
	Davidlohr Bueso <dbueso@suse.de>, linux-mm <linux-mm@kvack.org>,
	Ingo Molnar <mingo@kernel.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH 1/2] tracepoints: Add helper to test if tracepoint is enabled in a header
Date: Thu, 24 Sep 2020 15:40:09 -0400	[thread overview]
Message-ID: <20200924154009.4b45d56e@oasis.local.home> (raw)
In-Reply-To: <20200924153517.73f5f257@oasis.local.home>

On Thu, 24 Sep 2020 15:35:17 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:

> > I'm ok with tracepoint_enabled(). However, I would have placed it in
> > tracepoint.h rather than tracepoint-defs.h, and we should figure out
> > why people complain that tracepoint.h is including headers too
> > eagerly.  
> 
> I could see if it would work in tracepoints.h.
> 
> It might. I was just being extra cautious.

Well that blew up quick!

Try using tracepoint.h in include/linux/page_ref.h and
arch/x86/include/asm/msr.h and see what happens.

  CC      arch/x86/kernel/asm-offsets.s
In file included from /work/git/linux-trace.git/include/linux/srcu.h:20,
                 from /work/git/linux-trace.git/include/linux/tracepoint.h:16,
                 from /work/git/linux-trace.git/arch/x86/include/asm/msr.h:68,
                 from /work/git/linux-trace.git/arch/x86/include/asm/processor.h:22,
                 from /work/git/linux-trace.git/arch/x86/include/asm/cpufeature.h:5,
                 from /work/git/linux-trace.git/arch/x86/include/asm/thread_info.h:53,
                 from /work/git/linux-trace.git/include/linux/thread_info.h:38,
                 from /work/git/linux-trace.git/arch/x86/include/asm/preempt.h:7,
                 from /work/git/linux-trace.git/include/linux/preempt.h:78,
                 from /work/git/linux-trace.git/include/linux/spinlock.h:51,
                 from /work/git/linux-trace.git/include/linux/mmzone.h:8,
                 from /work/git/linux-trace.git/include/linux/gfp.h:6,
                 from /work/git/linux-trace.git/include/linux/slab.h:15,
                 from /work/git/linux-trace.git/include/linux/crypto.h:20,
                 from /work/git/linux-trace.git/arch/x86/kernel/asm-offsets.c:9:
/work/git/linux-trace.git/include/linux/rcupdate.h: In function ‘rcu_read_lock_sched’:
/work/git/linux-trace.git/include/linux/rcupdate.h:740:2: error: implicit declaration of function ‘preempt_disable’ [-Werror=implicit-function-declaration]
  740 |  preempt_disable();
      |  ^~~~~~~~~~~~~~~
/work/git/linux-trace.git/include/linux/rcupdate.h: In function ‘rcu_read_lock_sched_notrace’:
/work/git/linux-trace.git/include/linux/rcupdate.h:750:2: error: implicit declaration of function ‘preempt_disable_notrace’; did you mean ‘paravirt_disable_iospace’? [-Werror=implicit-function-declaration]
  750 |  preempt_disable_notrace();
      |  ^~~~~~~~~~~~~~~~~~~~~~~
      |  paravirt_disable_iospace
/work/git/linux-trace.git/include/linux/rcupdate.h: In function ‘rcu_read_unlock_sched’:
/work/git/linux-trace.git/include/linux/rcupdate.h:765:2: error: implicit declaration of function ‘preempt_enable’ [-Werror=implicit-function-declaration]
  765 |  preempt_enable();
      |  ^~~~~~~~~~~~~~
/work/git/linux-trace.git/include/linux/rcupdate.h: In function ‘rcu_read_unlock_sched_notrace’:
/work/git/linux-trace.git/include/linux/rcupdate.h:772:2: error: implicit declaration of function ‘preempt_enable_notrace’ [-Werror=implicit-function-declaration]
  772 |  preempt_enable_notrace();
      |  ^~~~~~~~~~~~~~~~~~~~~~

-- Steve