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migration: Wait for semaphore before completing migration

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

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
Dr. David Alan Gilbert 2017-10-20 10:05:52 +01:00 committed by Juan Quintela
parent 31e060774c
commit e91d8951d5
2 changed files with 41 additions and 0 deletions
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38
migration/migration.c
View file

@ -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("");

3
migration/migration.h
View file

@ -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;