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
> + 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?
> +}
> +
> +static void multifd_send_cleanup_state(void)
> +{
> + qemu_sem_destroy(&multifd_send_state->channels_ready);
> + g_free(multifd_send_state->params);
> + multifd_send_state->params = NULL;
> + multifd_pages_clear(multifd_send_state->pages);
> + multifd_send_state->pages = NULL;
> + g_free(multifd_send_state);
> + multifd_send_state = NULL;
> +}
> +
> void multifd_save_cleanup(void)
> {
> int i;
> @@ -615,48 +670,20 @@ void multifd_save_cleanup(void)
> if (!migrate_multifd()) {
> return;
> }
> +
> multifd_send_terminate_threads();
> - for (i = 0; i < migrate_multifd_channels(); i++) {
> - MultiFDSendParams *p = &multifd_send_state->params[i];
>
> - if (p->running) {
> - qemu_thread_join(&p->thread);
> - }
> - }
> for (i = 0; i < migrate_multifd_channels(); i++) {
> MultiFDSendParams *p = &multifd_send_state->params[i];
> Error *local_err = NULL;
>
> - 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, &local_err);
> - if (local_err) {
> + if (!multifd_send_cleanup_channel(p, &local_err)) {
> migrate_set_error(migrate_get_current(), local_err);
> error_free(local_err);
> }
> }
> - qemu_sem_destroy(&multifd_send_state->channels_ready);
> - g_free(multifd_send_state->params);
> - multifd_send_state->params = NULL;
> - multifd_pages_clear(multifd_send_state->pages);
> - multifd_send_state->pages = NULL;
> - g_free(multifd_send_state);
> - multifd_send_state = NULL;
> +
> + multifd_send_cleanup_state();
> }
>
> static int multifd_zero_copy_flush(QIOChannel *c)
