* Peter Xu ([email protected]) wrote:
> On Thu, Feb 03, 2022 at 03:19:48PM +0000, Dr. David Alan Gilbert wrote:
> > * Peter Xu ([email protected]) wrote:
> > > Postcopy create threads. A common manner is we init a sem and use it to
> > > sync
> > > with the thread. Namely, we have fault_thread_sem and listen_thread_sem
> > > and
> > > they're only used for this.
> > >
> > > Make it a shared infrastructure so it's easier to create yet another
> > > thread.
> > >
> >
> > It might be worth a note saying you now share that sem, so you can't
> > start two threads in parallel.
>
> I'll squash this into the patch:
Thanks
> ---8<---
> diff --git a/migration/migration.h b/migration/migration.h
> index 845be3463c..2a311fd8d6 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -72,7 +72,10 @@ struct MigrationIncomingState {
> /* A hook to allow cleanup at the end of incoming migration */
> void *transport_data;
> void (*transport_cleanup)(void *data);
> - /* Used to sync thread creations */
> + /*
> + * Used to sync thread creations. Note that we can't create threads in
> + * parallel with this sem.
> + */
> QemuSemaphore thread_sync_sem;
> /*
> * Free at the start of the main state load, set as the main thread
> finishes
> diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
> index 099d8ed478..1a3ba1db84 100644
> --- a/migration/postcopy-ram.c
> +++ b/migration/postcopy-ram.c
> @@ -79,6 +79,10 @@ int postcopy_notify(enum PostcopyNotifyReason reason,
> Error **errp)
> &pnd);
> }
>
> +/*
> + * NOTE: this routine is not thread safe, we can't call it concurrently. But
> it
> + * should be good enough for migration's purposes.
> + */
> void postcopy_thread_create(MigrationIncomingState *mis,
> QemuThread *thread, const char *name,
> void *(*fn)(void *), int joinable)
> ---8<---
>
> >
> > Reviewed-by: Dr. David Alan Gilbert <[email protected]>
>
> Thanks,
>
> --
> Peter Xu
>
--
Dr. David Alan Gilbert / [email protected] / Manchester, UK
