[PATCH 7/8] migration/colo: Replace QemuSemaphore with QemuEvent

[Akihiko Odaki]

colo_exit_sem and colo_incoming_sem represent one-shot events so they
can be converted into QemuEvent, which is more lightweight.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
 migration/migration.h |  6 +++---
 migration/colo.c      | 20 ++++++++++----------
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/migration/migration.h b/migration/migration.h
index 3eda64d7d241..14032e347ece 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -185,7 +185,7 @@ struct MigrationIncomingState {
 
     /* The coroutine we should enter (back) after failover */
     Coroutine *colo_incoming_co;
-    QemuSemaphore colo_incoming_sem;
+    QemuEvent colo_incoming_event;
 
     /*
      * PostcopyBlocktimeContext to keep information for postcopy
@@ -379,8 +379,8 @@ struct MigrationState {
     /* Migration is paused due to pause-before-switchover */
     QemuEvent pause_event;
 
-    /* The semaphore is used to notify COLO thread that failover is finished */
-    QemuSemaphore colo_exit_sem;
+    /* The event is used to notify COLO thread that failover is finished */
+    QemuEvent colo_exit_event;
 
     /* The event is used to notify COLO thread to do checkpoint */
     QemuEvent colo_checkpoint_event;
diff --git a/migration/colo.c b/migration/colo.c
index 9590f281d0f1..7e29c93aa4df 100644
--- a/migration/colo.c
+++ b/migration/colo.c
@@ -146,7 +146,7 @@ static void secondary_vm_do_failover(void)
         return;
     }
     /* Notify COLO incoming thread that failover work is finished */
-    qemu_sem_post(&mis->colo_incoming_sem);
+    qemu_event_set(&mis->colo_incoming_event);
 
     /* For Secondary VM, jump to incoming co */
     if (mis->colo_incoming_co) {
@@ -195,7 +195,7 @@ static void primary_vm_do_failover(void)
     }
 
     /* Notify COLO thread that failover work is finished */
-    qemu_sem_post(&s->colo_exit_sem);
+    qemu_event_set(&s->colo_exit_event);
 }
 
 COLOMode get_colo_mode(void)
@@ -617,8 +617,8 @@ out:
     }
 
     /* Hope this not to be too long to wait here */
-    qemu_sem_wait(&s->colo_exit_sem);
-    qemu_sem_destroy(&s->colo_exit_sem);
+    qemu_event_wait(&s->colo_exit_event);
+    qemu_event_destroy(&s->colo_exit_event);
 
     /*
      * It is safe to unregister notifier after failover finished.
@@ -648,7 +648,7 @@ void migrate_start_colo_process(MigrationState *s)
     s->colo_delay_timer =  timer_new_ms(QEMU_CLOCK_HOST,
                                 colo_checkpoint_notify_timer, NULL);
 
-    qemu_sem_init(&s->colo_exit_sem, 0);
+    qemu_event_init(&s->colo_exit_event, false);
     colo_process_checkpoint(s);
     bql_lock();
 }
@@ -805,11 +805,11 @@ void colo_shutdown(void)
     case COLO_MODE_PRIMARY:
         s = migrate_get_current();
         qemu_event_set(&s->colo_checkpoint_event);
-        qemu_sem_post(&s->colo_exit_sem);
+        qemu_event_set(&s->colo_exit_event);
         break;
     case COLO_MODE_SECONDARY:
         mis = migration_incoming_get_current();
-        qemu_sem_post(&mis->colo_incoming_sem);
+        qemu_event_set(&mis->colo_incoming_event);
         break;
     default:
         break;
@@ -824,7 +824,7 @@ static void *colo_process_incoming_thread(void *opaque)
     Error *local_err = NULL;
 
     rcu_register_thread();
-    qemu_sem_init(&mis->colo_incoming_sem, 0);
+    qemu_event_init(&mis->colo_incoming_event, false);
 
     migrate_set_state(&mis->state, MIGRATION_STATUS_ACTIVE,
                       MIGRATION_STATUS_COLO);
@@ -920,8 +920,8 @@ out:
     }
 
     /* Hope this not to be too long to loop here */
-    qemu_sem_wait(&mis->colo_incoming_sem);
-    qemu_sem_destroy(&mis->colo_incoming_sem);
+    qemu_event_wait(&mis->colo_incoming_event);
+    qemu_event_destroy(&mis->colo_incoming_event);
 
     rcu_unregister_thread();
     return NULL;

-- 
2.47.1