Messages in this thread | | | Date | Tue, 17 Jun 2008 01:28:26 -0600 | From | "Grant Likely" <> | Subject | Re: [PATCH 2/4] spi: split up spi_new_device() to allow two stage registration. |
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On Sat, May 24, 2008 at 12:43 AM, Grant Likely <grant.likely@secretlab.ca> wrote: > On Wed, May 21, 2008 at 6:17 PM, David Brownell <david-b@pacbell.net> 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.
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