Messages in this thread | | | Date | Wed, 7 Dec 2005 17:18:40 -0500 | From | Dmitry Torokhov <> | Subject | Re: [PATCH] Minor change to platform_device_register_simple prototype |
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On 12/7/05, Russell King <rmk+lkml@arm.linux.org.uk> wrote: > On Wed, Dec 07, 2005 at 01:23:11PM -0500, Dmitry Torokhov wrote: > > On 12/7/05, Russell King <rmk+lkml@arm.linux.org.uk> wrote: > > > On Wed, Dec 07, 2005 at 12:59:09PM -0500, Dmitry Torokhov > > I have started moving drivers from the "_simple" interface and I found > > > > that I'm missing platform_device_del that would complement > > > > platform_device_add. Would you object to having such a function, like > > > > we do for other sysfs objects? With it one can write somthing like > > > > this: > > > > > > Greg and myself discussed that, and we decided that it was adding > > > unnecessary complexity to the interface. Maybe Greg's view has > > > changed? > > > > > > > How do you write error handling path without the _del function if > > platform_device_add is not the last call? you can't call > > platform_device_unregister() and then platform_device_put(). And I > > don't like to take extra references in error path or assign the > > pointer to NULL in teh middle of unwinding... > > The example code in the commit comments contains a complete example of > registering a platform device, and cleaning up should something go > wrong with that process. >
The problem with what you proposing is that one will have to code 2 cleanup code paths - one when platform_device_add fails (in this case you just call platform_device_put) and another one when platfrom_device_add succeeds but something else fails. In the second case you have to use platfrom_device_unregister to release resources but can't use platform_device_put because the device will most likely be released by plaform_device_unregister. I prefer having single cleanup code path, like most other drivers have.
> Unregistering is just a matter of calling platform_device_unregister(). > An unregister call is a del + put in exactly the same way as it is > throughout the rest of the driver model. >
Yes, and it works just fine everywhere except in initialization code when you need to jump in the middle of _del + _put sequence.
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