A niggling leftover: what exactly are the __init and __exit macros we see within the preceding function signatures? These are merely memory optimization attributes inserted by the linker.
The __init macro defines an init.text section for code. Similarly, any data declared with the __initdata attribute goes into an init.data section. The whole point here is the code and data in the init function is used exactly once during initialization. Once it's invoked, it will never be called again; so, once called, it is then freed up (via free_initmem()).
The deal is similar with the __exit macro, though, of course, this only makes sense with kernel modules. Once the cleanup function is called, all the memory is freed. If the code were instead part of the static kernel image (or if module support were disabled), this macro would have no effect.
Fine, but so far, we have...
