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

[Paolo Bonzini]

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...

Paolo

>      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.