Re: [PATCH v2 08/17] migration: Add load_finish handler and associated functions

[Fabiano Rosas]

"Maciej S. Szmigiero" <mail@maciej.szmigiero.name> writes:

> From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>
>
> load_finish SaveVMHandler allows migration code to poll whether
> a device-specific asynchronous device state loading operation had finished.
>
> In order to avoid calling this handler needlessly the device is supposed
> to notify the migration code of its possible readiness via a call to
> qemu_loadvm_load_finish_ready_broadcast() while holding
> qemu_loadvm_load_finish_ready_lock.
>
> Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
> ---
>  include/migration/register.h | 21 +++++++++++++++
>  migration/migration.c        |  6 +++++
>  migration/migration.h        |  3 +++
>  migration/savevm.c           | 52 ++++++++++++++++++++++++++++++++++++
>  migration/savevm.h           |  4 +++
>  5 files changed, 86 insertions(+)
>
> diff --git a/include/migration/register.h b/include/migration/register.h
> index 4a578f140713..44d8cf5192ae 100644
> --- a/include/migration/register.h
> +++ b/include/migration/register.h
> @@ -278,6 +278,27 @@ typedef struct SaveVMHandlers {
>      int (*load_state_buffer)(void *opaque, char *data, size_t data_size,
>                               Error **errp);
>  
> +    /**
> +     * @load_finish
> +     *
> +     * Poll whether all asynchronous device state loading had finished.
> +     * Not called on the load failure path.
> +     *
> +     * Called while holding the qemu_loadvm_load_finish_ready_lock.
> +     *
> +     * If this method signals "not ready" then it might not be called
> +     * again until qemu_loadvm_load_finish_ready_broadcast() is invoked
> +     * while holding qemu_loadvm_load_finish_ready_lock.
> +     *
> +     * @opaque: data pointer passed to register_savevm_live()
> +     * @is_finished: whether the loading had finished (output parameter)
> +     * @errp: pointer to Error*, to store an error if it happens.
> +     *
> +     * Returns zero to indicate success and negative for error
> +     * It's not an error that the loading still hasn't finished.
> +     */
> +    int (*load_finish)(void *opaque, bool *is_finished, Error **errp);
> +
>      /**
>       * @load_setup
>       *
> diff --git a/migration/migration.c b/migration/migration.c
> index 3dea06d57732..d61e7b055e07 100644
> --- a/migration/migration.c
> +++ b/migration/migration.c
> @@ -259,6 +259,9 @@ void migration_object_init(void)
>  
>      current_incoming->exit_on_error = INMIGRATE_DEFAULT_EXIT_ON_ERROR;
>  
> +    qemu_mutex_init(&current_incoming->load_finish_ready_mutex);
> +    qemu_cond_init(&current_incoming->load_finish_ready_cond);
> +
>      migration_object_check(current_migration, &error_fatal);
>  
>      ram_mig_init();
> @@ -410,6 +413,9 @@ void migration_incoming_state_destroy(void)
>          mis->postcopy_qemufile_dst = NULL;
>      }
>  
> +    qemu_mutex_destroy(&mis->load_finish_ready_mutex);
> +    qemu_cond_destroy(&mis->load_finish_ready_cond);
> +
>      yank_unregister_instance(MIGRATION_YANK_INSTANCE);
>  }
>  
> diff --git a/migration/migration.h b/migration/migration.h
> index 38aa1402d516..4e2443e6c8ec 100644
> --- a/migration/migration.h
> +++ b/migration/migration.h
> @@ -230,6 +230,9 @@ struct MigrationIncomingState {
>  
>      /* Do exit on incoming migration failure */
>      bool exit_on_error;
> +
> +    QemuCond load_finish_ready_cond;
> +    QemuMutex load_finish_ready_mutex;

With these moved to MigrationState:

Reviewed-by: Fabiano Rosas <farosas@suse.de>