Commit e91d8951 authored by Dr. David Alan Gilbert's avatar Dr. David Alan Gilbert Committed by Juan Quintela
Browse files

migration: Wait for semaphore before completing migration 



Wait for a semaphore before completing the migration,
if the previously added capability was enabled.

Signed-off-by: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: default avatarPeter Xu <peterx@redhat.com>
Reviewed-by: default avatarJuan Quintela <quintela@redhat.com>
Signed-off-by: default avatarJuan Quintela <quintela@redhat.com>
parent 31e06077

migration/migration.c

+38 −0
Original line number Diff line number Diff line
@@ -1957,6 +1957,39 @@ fail: 
    return -1;

}



/**

 * migration_maybe_pause: Pause if required to by

 * migrate_pause_before_switchover called with the iothread locked

 * Returns: 0 on success

 */

static int migration_maybe_pause(MigrationState *s, int *current_active_state)

{

    if (!migrate_pause_before_switchover()) {

        return 0;

    }



    /* Since leaving this state is not atomic with posting the semaphore

     * it's possible that someone could have issued multiple migrate_continue

     * and the semaphore is incorrectly positive at this point;

     * the docs say it's undefined to reinit a semaphore that's already

     * init'd, so use timedwait to eat up any existing posts.

     */

    while (qemu_sem_timedwait(&s->pause_sem, 1) == 0) {

        /* This block intentionally left blank */

    }



    qemu_mutex_unlock_iothread();

    migrate_set_state(&s->state, *current_active_state,

                      MIGRATION_STATUS_PRE_SWITCHOVER);

    qemu_sem_wait(&s->pause_sem);

    migrate_set_state(&s->state, MIGRATION_STATUS_PRE_SWITCHOVER,

                      MIGRATION_STATUS_DEVICE);

    *current_active_state = MIGRATION_STATUS_DEVICE;

    qemu_mutex_lock_iothread();



    return s->state == MIGRATION_STATUS_DEVICE ? 0 : -EINVAL;

}



/**

 * migration_completion: Used by migration_thread when there's not much left.

 *   The caller 'breaks' the loop when this returns.
@@ -1982,6 +2015,9 @@ static void migration_completion(MigrationState *s, int current_active_state, 
        if (!ret) {

            bool inactivate = !migrate_colo_enabled();

            ret = vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);

            if (ret >= 0) {

                ret = migration_maybe_pause(s, &current_active_state);

            }

            if (ret >= 0) {

                qemu_file_set_rate_limit(s->to_dst_file, INT64_MAX);

                ret = qemu_savevm_state_complete_precopy(s->to_dst_file, false,
@@ -2363,6 +2399,7 @@ static void migration_instance_finalize(Object *obj) 


    g_free(params->tls_hostname);

    g_free(params->tls_creds);

    qemu_sem_destroy(&ms->pause_sem);

}



static void migration_instance_init(Object *obj)
@@ -2373,6 +2410,7 @@ static void migration_instance_init(Object *obj) 
    ms->state = MIGRATION_STATUS_NONE;

    ms->xbzrle_cache_size = DEFAULT_MIGRATE_CACHE_SIZE;

    ms->mbps = -1;

    qemu_sem_init(&ms->pause_sem, 0);



    params->tls_hostname = g_strdup("");

    params->tls_creds = g_strdup("");

migration/migration.h

+3 −0
Original line number Diff line number Diff line
@@ -121,6 +121,9 @@ struct MigrationState 
    /* Flag set once the migration thread called bdrv_inactivate_all */

    bool block_inactive;



    /* Migration is paused due to pause-before-switchover */

    QemuSemaphore pause_sem;



    /* The semaphore is used to notify COLO thread that failover is finished */

    QemuSemaphore colo_exit_sem;