Re: [PATCH v4 6/6] block-copy: atomic .cancelled and .finished fields in BlockCopyCallState

[Paolo Bonzini]

On 22/06/21 11:36, Vladimir Sementsov-Ogievskiy wrote:
> > It does.  If it returns true, you still want the load of finished to 
> > happen before the reads that follow.
>
> Hmm.. The worst case if we use just qatomic_read is that assertion will 
> not crash when it actually should. That doesn't break the logic. But 
> that's not good anyway.
>
> OK, I agree, let's keep it.

You can also have a finished job, but get a stale value for 
error_is_read or ret.  The issue is not in getting the stale value per 
se, but in block_copy_call_status's caller not expecting it.

(I understand you agree, but I guess it can be interesting to learn 
about this too).

Paolo