From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean Delvare Subject: Re: [PATCH 0/6] Make return type of i2c_del_adapter() (and i2c_del_mux_adapter()) void Date: Sun, 31 Mar 2013 09:56:23 +0200 Message-ID: <20130331095623.146f65db@endymion.delvare> References: <1362853009-20789-1-git-send-email-lars@metafoo.de> <20130330211352.07530db7@endymion.delvare> <51574E71.7010403@metafoo.de> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51574E71.7010403-Qo5EllUWu/uELgA04lAiVw@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Lars-Peter Clausen Cc: Wolfram Sang , Ben Dooks , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-i2c@vger.kernel.org On Sat, 30 Mar 2013 21:43:29 +0100, Lars-Peter Clausen wrote: > On 03/30/2013 09:13 PM, Jean Delvare wrote: > > I see: > > > > struct device_driver { > > (...) > > int (*probe) (struct device *dev); > > int (*remove) (struct device *dev); > > > > So the driver core does allow remove functions to return an error. > > Well, the return type is int, but the return value is never checked. So you > can return an error value, but the device driver core is going to care and > the device is still removed. So any code which does return an error in it's > probe function in the assumption that this means the device will still be > present is broken and leaves the system in an undefined state. So if that > happens the kernel will probably crash sooner or later, or if you are lucky > you only created a few resources leaks. > > And no we can't change the core to handle errors from a drivers remove > callback. It's a basic inherent property of the Linux device driver model > that any device can be removed at any time. > > > Are you going to fix all subsystems as you are doing for i2c now, and then > > change device_driver.remove to return void? If not, I don't see the > > point of changing it in i2c. > > As I said it's a bug if a driver returns an error in its remove function. > And the fact that the return type of the remove callback is int is pretty > much misleading in this regard, so the long term goal is to make the return > type void. But that's a long way to go until we get there, fixing the return > type of i2c_del_adapter() is kind of the low hanging fruit. OK, makes sense, thanks for the clarification. -- Jean Delvare