On Sat, 29 Dec 2018, Arnd Bergmann wrote:
I had a look at the complete series now, and I think this is a great cleanup. I replied with a couple of minor comments that you may or may not want to address first.
Thanks for reviewing this.
The one thing I would like to see resolved (I hope this doesn't bring back an old discussion you had already concluded) is regarding the use of a global exported structure of function pointers, as opposed to using either directly exported functions (with a consistent interface) or a boot-time selectable structure like dma_map_ops or ppc_md.
If I understand correctly, /dev/nvram was made obsolete by the nvmem subsystem (?). If so, there won't be new /dev/nvram users, and the refactoring here only has to be sufficiently flexible to meet the needs of existing users. I'm not opposed to exported functions in place of a singleton ops struct. Other things being equal I'm inclined toward the ops struct, perhaps because I like encapsulation or perhaps because I don't like excess generality. (That design decision was made years ago and I don't remember the reasoning.) All the arch_nvram_ops structs that I've defined in these patches have the 'const' properly: const struct nvram_ops arch_nvram_ops = { .read_byte = nvram_read_byte, .write_byte = nvram_write_byte, .read = nvram_read, .write = nvram_write, .get_size = nvram_get_size, .set_checksum = nvram_set_checksum, .initialize = nvram_initialize, }; EXPORT_SYMBOL(arch_nvram_ops); This is because there's no need to do any run-time reconfiguration. Is a collection of exported functions a better fit here? --
Arnd