[Qemu-devel] Re: vmstate: Useless post_save?

[Juan Quintela <quintela@redhat.com>]

Jan Kiszka <jan.kiszka@web.de> wrote:
> Hi all,
>
> I wondered why we have the post_save callback in vmstate. Conceptually,
> it made no sense to me. So I grep'ed for its users - and found exactly
> one: tmp105. As suspected, only "strange" code was found:
>
> static void tmp105_post_save(void *opaque)
> {
>     TMP105State *s = opaque;
>     s->faults = tmp105_faultq[(s->config >> 3) & 3];            /* F */
> }
>
> First, s->config cannot be changed by saving the state. And, second,
> s->faults is only written by this driver, never read.
>
> Anyone any concerns dropping 'faults' from tmp105 and then dropping the
> post_save handler from vmstate?

About 'faults' dropping, I have to opinion at all.  It is done this way
because old code did it this way.

About post_save() it should be there only to "undo" things done in
"pre_save" to be able to continue in the source after a failed
migration.

As you have found, not much users around.  If you remove tmp105 user, I
vote to remove it.  We can "revert" the removal if need appears again.

Later, Juan.