Re: [PATCH 4/5] shmem: use call_once()

Hugh Dickins
2008-03-11T20:56:22Z

On Tue, 11 Mar 2008, Akinobu Mita wrote:
> 2008/3/11, Hugh Dickins <hugh@veritas.com>:
> > On Tue, 11 Mar 2008, Akinobu Mita wrote:
> > > This patch defers mounting tmpfs till shmem_file_setup() is
> > > called first time by using call_once().
> >
> > Please explain why we might need this patch: is something changing
> > elsewhere? Or are you misled by that "module_init(init_tmpfs)"
> > into thinking that mm/shmem.c is sometimes built modular?
>
> If no processes call shmem_file_setup() (via shm_get(2)), it is unnecessary
or shmem_zero_setup, not very common
> to do vfs_kern_mount(&tmpfs_fs_type, ...) unconditionary in boot-time.
> So I thought it is suitable example to demonstrate how to use "call_once()"
> in this patch set.

Oh, I see, thanks. Well, I don't feel all that strongly about it; but
on the whole I'd prefer we leave it as part of the __init, than change
it around to provide this example (and risk introducing some weird issue
e.g. related to its "dev"?). I guess the same should go for the huge
and the tiny, whereas you have better justification in the idr case.
Call me over-cautious.

Hugh