Date: Mon, 10 Sep 2007 13:17:59 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Adrian Bunk <bunk@kernel.org>
Cc: Al Viro <viro@ftp.linux.org.uk>, Christoph Hellwig <hch@infradead.org>,
       perex@suse.cz, linux-kernel@vger.kernel.org
Subject: Re: [-mm patch] unexport sys_{open,read}
Message-Id: <20070910131759.a7b2dce7.akpm@linux-foundation.org>
In-Reply-To: <20070910195821.GH3563@stusta.de>
References: <20070909202527.GT3563@stusta.de>
	<20070909203920.GA11764@infradead.org>
	<20070909145940.0b41c8a5.akpm@linux-foundation.org>
	<20070910090808.GA31204@infradead.org>
	<20070910022324.c69e1897.akpm@linux-foundation.org>
	<20070910124358.GB21089@ftp.linux.org.uk>
	<20070910102556.de35e825.akpm@linux-foundation.org>
	<20070910195821.GH3563@stusta.de>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 2232
Lines: 50

On Mon, 10 Sep 2007 21:58:21 +0200 Adrian Bunk <bunk@kernel.org> wrote:

> On Mon, Sep 10, 2007 at 10:25:56AM -0700, Andrew Morton wrote:
> >...
> > Also, Adrian goes on and on with weird theories about how I'm picking on
> > him.  But other patches (such as 7d12e780e003f93433d49ce78c) DO OTHER
> > STUFF.  Like simplify the code, and make it smaller, faster or more
> > maintainable or more reliable.
> 
> The unexport of sys_{open,read} actually makes the kernel smaller...
> 
> > So the tradeoff is quite different from a
> > one-liner which does nothing but kill an export.  And, contrary to his
> > claims, we _do_ put temporary back-compat wrappers in there when we
> > change interfaces on those relatively rare occasions when it is possible,
> > and when we remember to do it.
> 
> Your tradeoff misses the impact on external modules.
> 
> The unexport of sys_open will not break many modules, while
> commit 7d12e780e003f93433d49ce78c most likely broke the majority of 
> external modules.
> 
> Do we guarantee some API stability to module authors or do we not 
> guarantee this?

Neither.  We look at each change and make sensible decisions based upon a
number of factors.

> Emphasizing on API stability in the cases that don't matter much while 
> breaking the API in cases that affect most modules doesn't make any 
> sense at all.
> 
> And your "remember to do it" is an important point. As an example, every 
> change to a struct that is part of the signature of one or exportted 
> functions does change the API of all of these functions. If we offer any 
> API stability for external modules we need to review all patches that 
> touch include/ because many of them contain changes to the modules API 
> that might otherwise get missed.
> 
> Let's either continue to state that their is no stable API for external 
> modules or define some API stability rules and do whatever is required 
> for implementing them.

There is no benefit in making some rigid set of rules.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/