migration: allow fault thread to pause

Allows the fault thread to stop handling page faults temporarily. When
network failure happened (and if we expect a recovery afterwards), we
should not allow the fault thread to continue sending things to source,
instead, it should halt for a while until the connection is rebuilt.

When the dest main thread noticed the failure, it kicks the fault thread
to switch to pause state.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Message-Id: <20180502104740.12123-7-peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/migration/migration.c b/migration/migration.c
index f9c58d2511..3d3b0a5b4a 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -160,6 +160,7 @@ MigrationIncomingState *migration_incoming_get_current(void)
         qemu_mutex_init(&mis_current.rp_mutex);
         qemu_event_init(&mis_current.main_thread_load_event, false);
         qemu_sem_init(&mis_current.postcopy_pause_sem_dst, 0);
+        qemu_sem_init(&mis_current.postcopy_pause_sem_fault, 0);
 
         init_dirty_bitmap_incoming_migration();