Return-path: Received: from caramon.arm.linux.org.uk ([78.32.30.218]:53755 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752016Ab0HFOrK (ORCPT ); Fri, 6 Aug 2010 10:47:10 -0400 Date: Fri, 6 Aug 2010 15:46:05 +0100 From: Russell King - ARM Linux To: Ohad Ben-Cohen Cc: Linus Walleij , Vitaly Wool , Kalle Valo , Pandita Vikram , Nicolas Pitre , Tony Lindgren , linux-wireless@vger.kernel.org, Roger Quadros , linux-mmc@vger.kernel.org, San Mehat , Chikkature Rajashekar Madhusudhan , Luciano Coelho , linux-omap@vger.kernel.org, akpm@linux-foundation.org, linux-arm-kernel@lists.infradead.org, Ido Yariv Subject: Re: [PATCH v2 03/20] mmc: support embedded data field in mmc_host Message-ID: <20100806144605.GA21015@n2100.arm.linux.org.uk> References: <20100804114147.GB6852@n2100.arm.linux.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: Sender: linux-wireless-owner@vger.kernel.org List-ID: On Fri, Aug 06, 2010 at 01:02:24PM +0300, Ohad Ben-Cohen wrote: > We have Russell's suggestion which is nice and simple, but it has the > 1 device limitation. You could make it generic by doing something like this: #define set_device_data(name, type, index, data) \ ({ \ extern void __set_device_data(const char *, int, void *, size_t); \ BUILD_BUG_ON(!__same_type(type, *data)); \ __set_device_data(name ":" #type, index, data, sizeof(type)); \ }) #define get_device_data(name, type, index) ({ \ extern void *__get_device_data(const char *, int); \ type *__ptr = __get_device_data(name ":" #type, index); \ __ptr; }) And now we have something that takes a string and index to use as a lookup key in some kind of list - and it's typesafe (because the lookup key is dependent on the stringified type.) But... at this point I feel that we're getting too complicated, and will get shouted at to use something like DT which already solves this problem.