From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756005AbYELWSZ (ORCPT ); Mon, 12 May 2008 18:18:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751938AbYELWSR (ORCPT ); Mon, 12 May 2008 18:18:17 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:47415 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751546AbYELWSQ (ORCPT ); Mon, 12 May 2008 18:18:16 -0400 Date: Mon, 12 May 2008 15:18:05 -0700 From: Andrew Morton To: Grant Likely Cc: linux-kernel@vger.kernel.org, spi-devel-general@lists.sourceforge.net, dbrownell@users.sourceforge.net Subject: Re: [PATCH/RFC] spi: Change modalias from a pointer to a character array Message-Id: <20080512151805.4c2763b9.akpm@linux-foundation.org> In-Reply-To: <20080509173146.2932.16141.stgit@trillian.secretlab.ca> References: <20080509173146.2932.16141.stgit@trillian.secretlab.ca> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 09 May 2008 11:32:28 -0600 Grant Likely wrote: > From: Grant Likely > > Currently, 'modalias' in the spi_device structure is a 'const char *'. > The spi_new_device() function fills in the modalias value from a passed > in spi_board_info data block. Since it is a pointer copy, the new > spi_device remains dependent on the spi_board_info structure after the > new spi_device is registered (no other fields in spi_device directly > depend on the spi_board_info structure; all of the other data is copied). > > This causes a problem when dynamically propulating the list of attached > SPI devices. For example, in arch/powerpc, the list of SPI devices can > be populated from data in the device tree. With the current code, the > device tree adapter must kmalloc() a new spi_board_info structure for > each new SPI device it finds in the device tree, and there is no simple > mechanism in place for keeping track of these allocations. > > This patch changes modalias from a 'const char *' to a fixed char array. > By copying the modalias string instead of referencing it, the dependency > on the spi_board_info structure is eliminated and an outside caller does > not need to maintain a separate spi_board_info allocation for each device. > > If searched through the code to the best of my ability for any references > to modalias which may be affected by this change and haven't found anything. > It has been tested with the lite5200b platform in arch/powerpc. > > Signed-off-by: Grant Likely > --- > > drivers/spi/spi.c | 2 +- > include/linux/spi/spi.h | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c > index 1ad12af..bdf1b70 100644 > --- a/drivers/spi/spi.c > +++ b/drivers/spi/spi.c > @@ -229,7 +229,7 @@ struct spi_device *spi_new_device(struct spi_master *master, > proxy->max_speed_hz = chip->max_speed_hz; > proxy->mode = chip->mode; > proxy->irq = chip->irq; > - proxy->modalias = chip->modalias; > + strncpy(proxy->modalias, chip->modalias, KOBJ_NAME_LEN); > > snprintf(proxy->dev.bus_id, sizeof proxy->dev.bus_id, > "%s.%u", master->dev.bus_id, > diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h > index 387e428..38a080b 100644 > --- a/include/linux/spi/spi.h > +++ b/include/linux/spi/spi.h > @@ -82,7 +82,7 @@ struct spi_device { > int irq; > void *controller_state; > void *controller_data; > - const char *modalias; > + char modalias[KOBJ_NAME_LEN]; > > /* > * likely need more hooks for more protocol options affecting how I'm not really able to work out if this is a needed-in-2.6.26 thing. I assumed "not".