Re: [PATCH v8 00/25] Re-use nvram module

From: Finn Thain
Date: Sat Dec 29 2018 - 19:09:23 EST

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,

This is because there's no need to do any run-time reconfiguration.

Is a collection of exported functions a better fit here?


> Arnd