Re: [RFC PATCH 1/3] init.h: Add __init_str / __exit_str macros

From: Mathias Krause <minipli@googlemail.com>
To: Joe Perches <joe@perches.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Jason Baron <jbaron@redhat.com>
Subject: Re: [RFC PATCH 1/3] init.h: Add __init_str / __exit_str macros
Date: Tue, 24 Jun 2014 22:13:52 +0200	[thread overview]
Message-ID: <CA+rthh_-i2z3hrsefD2dTXitoSfbMcnqmWS17T8jweHQPA2FWQ@mail.gmail.com> (raw)
In-Reply-To: <1403639030.29061.37.camel@joe-AO725>

On 24 June 2014 21:43, Joe Perches <joe@perches.com> wrote:
> On Mon, 2014-06-23 at 00:46 +0200, Mathias Krause wrote:
>> Add macros to be able to mark string literals used in __init / __exit
>> functions.
> []
>> diff --git a/include/linux/init.h b/include/linux/init.h
> []
>> +#define __init_str(str)      __mark_str(str, __UNIQUE_ID(_init_str_), __initconst)
>> +#define __exit_str(str)      __mark_str(str, __UNIQUE_ID(_exit_str_), __exitdata)
>> +#define __mark_str(str, var, __section) \
>> +     ({ static const char var[] __section __aligned(1) = str; var; })
>> +
>
> You probably want to make these strings vanish
> completely when !CONFIG_PRINTK.
>
> As is, they will always exist in the image.

They will not. They are vanished as printk() is an empty static inline
function for the !CONFIG_PRINTK case. gcc is clever enough to optimize
the variables away in this case.

Thanks,
Mathias