Message-ID: <1404161370.2717.10.camel@joe-AO725>
Subject: Re: [RFC 1/1] proc: constify seq_operations
From: Joe Perches <joe@perches.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Fabian Frederick <fabf@skynet.be>, linux-kernel@vger.kernel.org
Date: Mon, 30 Jun 2014 13:49:30 -0700
In-Reply-To: <20140630133939.c24cd71919cd28c90992d6e1@linux-foundation.org>
References: <1404154997-15490-1-git-send-email-fabf@skynet.be>
	 <20140630133939.c24cd71919cd28c90992d6e1@linux-foundation.org>
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Sender: linux-kernel-owner@vger.kernel.org

On Mon, 2014-06-30 at 13:39 -0700, Andrew Morton wrote:
> On Mon, 30 Jun 2014 21:03:17 +0200 Fabian Frederick <fabf@skynet.be> wrote:
> 
> > proc_uid_seq_operations, proc_gid_seq_operations and proc_projid_seq_operations
> > are only called in proc_id_map_open with seq_open as
> > const struct seq_operations so we can constify the 3 structures and update
> > proc_id_map_open prototype.
> 
> There are an absolutely enormous number of places where we could
> constify things.

Which would be a good thing.

>   For sheer sanity's sake I'm not inclined to churn the
> code in this way unless a patch provides some sort of runtime benefit. 
> And this particular patch doesn't appear to change the generated code
> at all.

It moves ~100 bytes from data to text
(gcc 4.8)

$ size kernel/user_namespace.o*
   text	   data	    bss	    dec	    hex	filename
   6676	   3107	   2248	  12031	   2eff	kernel/user_namespace.o.new
   6580	   3211	   2248	  12039	   2f07	kernel/user_namespace.o.old


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