Re: [PATCH v2 7/7] block-copy: protect BlockCopyState .method fields

[Vladimir Sementsov-Ogievskiy]

28.05.2021 14:01, Paolo Bonzini wrote:
> On 28/05/21 12:24, Paolo Bonzini wrote:
> > It's still more complicated, because you need to add some kind of
> >
> >      method = s->method;
>
> This would even have to be a separate, one-line critical section...

Hm, so, we should set .use_copy_range in task, when it is initialized.

> >      ret = block_copy_do_copy(..., method);
> >      if (ret < 0 && method <= COPY_RANGE_SMALL) {
> >          method = COPY_RANGE_READ_WRITE;
> >          ret = block_copy_do_copy(..., method);
> >          }
> >      lock();
> >          if (method == s->method) {
> >              /* compute new method */
> >          }
> >
> > which makes it more complicated than this patch IMO.  But yeah at least it's a 
> > viable alternative to the atomics.

OK, I'm OK with patch as is. Finally I can refactor it later on top if needed.. 
I'll try now do some refactoring, you'll probably want to base on it, or 
vise-versa, I'll rebase it later on top of these patches.

--
Best regards,
Vladimir