On Fri, Feb 02, 2024 at 05:54:23PM -0300, Fabiano Rosas wrote:
> pet...@redhat.com writes:
>
> > From: Peter Xu <pet...@redhat.com>
> >
> > Shrink the function by moving relevant works into helpers: move the thread
> > join()s into multifd_send_terminate_threads(), then create two more helpers
> > to cover channel/state cleanups.
> >
> > Add a TODO entry for the thread terminate process because p->running is
> > still buggy. We need to fix it at some point but not yet covered.
> >
> > Suggested-by: Fabiano Rosas <faro...@suse.de>
> > Signed-off-by: Peter Xu <pet...@redhat.com>
>
> Reviewed-by: Fabiano Rosas <faro...@suse.de>
>
> minor comment below
>
> > ---
> > migration/multifd.c | 91 +++++++++++++++++++++++++++++----------------
> > 1 file changed, 59 insertions(+), 32 deletions(-)
> >
> > diff --git a/migration/multifd.c b/migration/multifd.c
> > index 4ab8e6eff2..4cb0d2cc17 100644
> > --- a/migration/multifd.c
> > +++ b/migration/multifd.c
> > @@ -593,6 +593,11 @@ static void multifd_send_terminate_threads(void)
> > * always set it.
> > */
> > qatomic_set(&multifd_send_state->exiting, 1);
> > +
> > + /*
> > + * Firstly, kick all threads out; no matter whether they are just idle,
> > + * or blocked in an IO system call.
> > + */
> > for (i = 0; i < migrate_multifd_channels(); i++) {
> > MultiFDSendParams *p = &multifd_send_state->params[i];
> >
> > @@ -601,6 +606,21 @@ static void multifd_send_terminate_threads(void)
> > qio_channel_shutdown(p->c, QIO_CHANNEL_SHUTDOWN_BOTH, NULL);
> > }
> > }
> > +
> > + /*
> > + * Finally recycle all the threads.
> > + *
> > + * TODO: p->running is still buggy, e.g. we can reach here without the
> > + * corresponding multifd_new_send_channel_async() get invoked yet,
> > + * then a new thread can even be created after this function returns.
> > + */
>
> Series on the list:
>
> https://lore.kernel.org/r/20240202191128.1901-1-faro...@suse.de
Thanks a lot. I'll read it later today.
>
> > + for (i = 0; i < migrate_multifd_channels(); i++) {
> > + MultiFDSendParams *p = &multifd_send_state->params[i];
> > +
> > + if (p->running) {
> > + qemu_thread_join(&p->thread);
> > + }
> > + }
> > }
> >
> > static int multifd_send_channel_destroy(QIOChannel *send)
> > @@ -608,6 +628,41 @@ static int multifd_send_channel_destroy(QIOChannel
> > *send)
> > return socket_send_channel_destroy(send);
> > }
> >
> > +static bool multifd_send_cleanup_channel(MultiFDSendParams *p, Error
> > **errp)
> > +{
> > + if (p->registered_yank) {
> > + migration_ioc_unregister_yank(p->c);
> > + }
> > + multifd_send_channel_destroy(p->c);
> > + p->c = NULL;
> > + qemu_mutex_destroy(&p->mutex);
> > + qemu_sem_destroy(&p->sem);
> > + qemu_sem_destroy(&p->sem_sync);
> > + g_free(p->name);
> > + p->name = NULL;
> > + multifd_pages_clear(p->pages);
> > + p->pages = NULL;
> > + p->packet_len = 0;
> > + g_free(p->packet);
> > + p->packet = NULL;
> > + g_free(p->iov);
> > + p->iov = NULL;
> > + multifd_send_state->ops->send_cleanup(p, errp);
> > +
> > + return *errp == NULL;
>
> I think technically this would require the ERRP_GUARD() macro?
I normally only use ERRP_GUARD() if there can be any caller passing in
NULL, or when I am not sure it's always !NULL.
What I wanted to add here is actually assert(errp), but then I noticed
*errp==NULL plays the same role as that, because if errp==NULL, it'll crash
here when dereferencing, so it actually has an implicit assert(errp);
exactly what I wanted, but even one line less (even if not obvious).
--
Peter Xu
