Re: [PATCH v2 5/7] block-copy: add QemuMutex lock for BlockCopyCallState list

[Emanuele Giuseppe Esposito]

On 21/05/2021 17:01, Paolo Bonzini wrote:
> On 20/05/21 17:30, Vladimir Sementsov-Ogievskiy wrote:
> > 18.05.2021 13:07, Emanuele Giuseppe Esposito wrote:
> > > As for BlockCopyTask, add a lock to protect BlockCopyCallState
> > > ret and sleep_state fields. Also move ret, finished and cancelled
> > > in the OUT fields of BlockCopyCallState.
> > >
> > > Here a QemuMutex is used to protect QemuCoSleep field, since it
> > > can be concurrently invoked also from outside threads.

Actually I don't even protect it here, I should have deleted the above 
line. I left a TODO for the QemuCoSleep field.

> > > .finished, .cancelled and reads to .ret and .error_is_read will be
> > > protected in the following patch.
> > >
> > > .sleep state is handled in the series "coroutine: new sleep/wake API"
> >
> > Could we live with one mutex for all needs? Why to add one more?
>
> This patch should just go away; the QemuMutex will not be needed once 
> QemuCoSleep is thread safe, while right now it is still racy.

At this point, I would just rename the other lock (tasks_lock) in "lock" 
or "state_lock", and substitute it in the calls_lock usages of this 
patch. Depending on how it comes out, I may merge this with the previous 
patch.

Thank you,
Emanuele