netdev - Re: [PATCH] proc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <200710281858.23705.zippel@linux-m68k.org>
Date:	Sun, 28 Oct 2007 19:58:22 +0200
From:	Roman Zippel <zippel@...ux-m68k.org>
To:	Russell King <rmk+lkml@....linux.org.uk>
Cc:	Joe Perches <joe@...ches.com>,
	Alexey Dobriyan <adobriyan@...il.com>, akpm@...l.org,
	torvalds@...l.org, viro@...iv.linux.org.uk,
	linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	linux-arch@...r.kernel.org
Subject: Re: [PATCH] proc_fs.h redux

Hi,

On Sunday 28 October 2007, Russell King wrote:

> On Sat, Oct 27, 2007 at 03:40:04PM -0700, Joe Perches wrote:
> > and forward declarations of
> >
> > struct proc_dir_entry;
> > struct file_operations;
> >
> > As a general rule, I think it better to use includes
> > than use naked forward declarations.
>
> If you go down that route, you end up with _lots_ of circular
> dependencies - header file X needs Y needs Z which needs X.  We've
> been there, several times.  It very quickly becomes quite
> unmaintainable - you end up with hard to predict behaviour from
> include files.
>
> The only realistic solution is to use forward declarations.

It's unfortunately more complicated than that. What basically needs to be done 
is to separate declarations from its users (usually inline functions). The 
problem is to correctly pull the declarations from the <asm/...> and 
<linux/...> header in the correct order. A typical mistake is to put 
declarations and inline functions in the same linux header and then include 
some additional from an asm header. For most high level header it's not much 
of a problem, but let's take <linux/list.h> as example. struct list_head is 
used everywhere, but just to get this one definition one also gets quite a 
few other dependencies as well.

bye, Roman
-
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html