Re: [PATCH v2 6/7] block-copy: atomic .cancelled and .finished fields in BlockCopyCallState

[Vladimir Sementsov-Ogievskiy]

21.05.2021 18:02, Paolo Bonzini wrote:
> On 20/05/21 17:34, Vladimir Sementsov-Ogievskiy wrote:
> > > By adding acquire/release pairs, we ensure that .ret and .error_is_read
> > > fields are written by block_copy_dirty_clusters before .finished is true.
> >
> > As I already said, please, can we live with one mutex for now? finished, ret, 
> > error_is_read, all these variables are changing rarely. I doubt that 
> > performance is improved by these atomic operations. But complexity of the 
> > architecture increases exponentially.
>
> The problem is that these are used outside coroutines. load-acquire/store-release is the 
> simplest way to handle a "finished" flag really.

Related, maybe we can support CoMutex outside of coroutine context?

Create a coroutine, which will lock the mutex and unlock it for us... Or 
something like this.. It will help the task of making everything thread-safe a 
lot


--
Best regards,
Vladimir