From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from an-out-0708.google.com (an-out-0708.google.com [209.85.132.248]) by ozlabs.org (Postfix) with ESMTP id 96DA5DDE00 for ; Tue, 17 Jun 2008 17:28:27 +1000 (EST) Received: by an-out-0708.google.com with SMTP id c34so1099786anc.78 for ; Tue, 17 Jun 2008 00:28:26 -0700 (PDT) Message-ID: Date: Tue, 17 Jun 2008 01:28:26 -0600 From: "Grant Likely" Sender: glikely@secretlab.ca To: "David Brownell" Subject: Re: [PATCH 2/4] spi: split up spi_new_device() to allow two stage registration. In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 References: <20080516193054.28030.35126.stgit@trillian.secretlab.ca> <20080516193608.28030.34968.stgit@trillian.secretlab.ca> <200805211717.13206.david-b@pacbell.net> Cc: linuxppc-dev@ozlabs.org, fabrizio.garetto@gmail.com, linux-kernel@vger.kernel.org, spi-devel-general@lists.sourceforge.net List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Sat, May 24, 2008 at 12:43 AM, Grant Likely wrote: > On Wed, May 21, 2008 at 6:17 PM, David Brownell wrote: >> On Friday 16 May 2008, Grant Likely wrote: >>> >>> This patch splits the allocation and registration portions of code out >>> of spi_new_device() and creates three new functions; spi_alloc_device(), >>> spi_register_device(), and spi_device_release(). >> >> I have no problem with the first two, but why the last? >> >> If the devices are always allocated by spi_alloc_device() as >> they should be -- probably through an intermediary -- the >> only public function necessary for that cleanup should be >> the existing spi_dev_put(). > > Ah, okay. I'm still a bit fuzzy on the device model conventions. > I'll remove that then. I've dug into this some more. spi_alloc_device only allocates the memory. It doesn't call device_initialize() to initialize the kref. All of that behaviour is handled within device_register(). Therefore if a driver uses spi_alloc_device() and then if a later part of the initialization fails before spi_register_device() is called, then the alloc'd memory needs to be freed, but spi_dev_put() won't work because the kobj isn't set up so I need another function to handle freeing it in on a failure path. Should I switch things around to do device_initialize() in the alloc function and call device_add() instead of device_register() in the spi_register_device() function? Is that sufficient to make put_device() work? Cheers, g. -- Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd.