From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <456D2B8E.4060802@yahoo.com.au> Date: Wed, 29 Nov 2006 17:41:18 +1100 From: Nick Piggin MIME-Version: 1.0 Subject: Re: Slab: Remove kmem_cache_t References: <456D0757.6050903@yahoo.com.au> <456D0FC4.4050704@yahoo.com.au> <20061128200619.67080e11.akpm@osdl.org> <456D1D82.3060001@yahoo.com.au> <20061128222409.cda8cd5e.akpm@osdl.org> In-Reply-To: <20061128222409.cda8cd5e.akpm@osdl.org> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: Christoph Lameter , linux-mm@kvack.org, Linus Torvalds List-ID: Andrew Morton wrote: > On Wed, 29 Nov 2006 16:41:22 +1100 > Nick Piggin wrote: > > >>Andrew Morton wrote: >> >>>On Wed, 29 Nov 2006 15:42:44 +1100 >>>Nick Piggin wrote: >>> >>> >>> >>>>So what exactly is wrong with >>>>a kmem_cache_t declaration in include files, then? >>> >>> >>>a) it's a typedef and >>> >>>b) it's a typedef, and you cannot forward-declare typedefs. We've hit this >>> a couple of times. Header files need to include slab.h just to be able to do >>> >>> extern kmem_cache_t *wozzle; >> >>So why doesn't >> >> typedef struct kmem_cache kmem_cache_t; >> extern kmem_cache_t *wozzle; >> >>work? >> > > > Well, you'd just do > > extern struct kmem_cache *wozzle; > > because you "know" that struct kmem_cache == kmem_cache_t. The compiler > will swallow it all. > > Do I need to explain how much that sucks? > Well the only code that is doing this is presumably some slab internal stuff. And that does "know" that struct kmem_cache == kmem_cache_t. Actually, once struct kmem_cache gets moved into slab.h, I would be interested to know what remaining forward dependencies are needed at all. Christoph? To be clear: this won't be some random driver or subsystem code (or even anything outside of mm/slab.c, hopefully) that is doing this, will it? If so then it sounds like just the kind of horrible design that we should be trying to get away from (whether we're using kmem_cache_t or struct kmem_cache as the caller-visible slab handle). -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org