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From: Petr Mladek <pmladek@suse.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Sergey Senozhatsky <senozhatsky@chromium.org>,
	John Ogness <john.ogness@linutronix.de>
Subject: Re: header circular dependencies
Date: Tue, 4 Jan 2022 15:45:24 +0100	[thread overview]
Message-ID: <YdRdhE9z+Yyxwrhj@alley> (raw)
In-Reply-To: <CAHp75Vdjp9_67xe0PeZ9LzcJ=eNxB0qVqPJqtFEvh3SDgcdODw@mail.gmail.com>

On Wed 2021-12-22 21:08:39, Andy Shevchenko wrote:
> `make headerdep` is full of printk.h circular dependencies, like
> 
> include/kvm/arm_vgic.h:18: warning: recursive header inclusion
> In file included from linux/printk.h,
>                 from linux/dynamic_debug.h:188
>                 from linux/printk.h:555 <-- here

This one looks like false positive:

   + printk.h includes dynamic_debug.h when CONFIG_DYNAMIC_DEBUG_CORE
   + dynamic_debug.h includes printk.h when !CONFIG_DYNAMIC_DEBUG_CORE

But there seem to be other cycles, for example:

   + printk.h
     + dynamic_debug.h
       + jump_label.h
	 + bug.h
	   + asm/bug.h
	     + printk.h

I guess that it somehow works _only_ because printk.h includes
dynamic_debug.h late. It probably defines everything that is needed
by bug.h early enough.

> I'm wondering if it's a false positive?
> In either case, can we teach the headerdep not to complain by fixing
> the culprit?

I am scratching my head how to clean this up. All the dependencies
make sense. The main problem is that all headers provide a lot of
inlined functionality. The inlining is often important either because
of speed or because every caller needs to have its own data structure
(struct _ddebug, struct static_key).

I can't find any good solution at the moment. But I am still slowed
down after the holidays.

Best Regards,
Petr

  parent reply	other threads:[~2022-01-04 14:46 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-22 19:08 header circular dependencies Andy Shevchenko
2021-12-22 19:10 ` Andy Shevchenko
2022-01-04 14:45 ` Petr Mladek [this message]
2022-01-04 14:52   ` Andy Shevchenko
2022-01-05  8:46     ` Petr Mladek

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