migration: make qemu_fopen_ops_buffered() return void

We want the file assignment to happen before the thread is created to
avoid locking, so we just do it before creating the thread.

Signed-off-by: Juan Quintela <quintela@redhat.com>

Reviewed-by: Orit Wasserman <owasserm@redhat.com>

buffered_file.c

@@ -32,7 +32,6 @@ typedef struct QEMUFileBuffered
     size_t buffer_size;
     size_t buffer_capacity;
     QemuThread thread;
-    bool complete;
 } QEMUFileBuffered;
 
 #ifdef DEBUG_BUFFERED_FILE
@@ -162,7 +161,7 @@ static int buffered_close(void *opaque)
         ret = ret2;
     }
     ret = migrate_fd_close(s->migration_state);
-    s->complete = true;
+    s->migration_state->complete = true;
     return ret;
 }
 
@@ -231,7 +230,7 @@ static void *buffered_file_thread(void *opaque)
     while (true) {
         int64_t current_time = qemu_get_clock_ms(rt_clock);
 
-        if (s->complete) {
+        if (s->migration_state->complete) {
             break;
         }
         if (s->freeze_output) {
@@ -263,7 +262,7 @@ static const QEMUFileOps buffered_file_ops = {
     .set_rate_limit = buffered_set_rate_limit,
 };
 
-QEMUFile *qemu_fopen_ops_buffered(MigrationState *migration_state)
+void qemu_fopen_ops_buffered(MigrationState *migration_state)
 {
     QEMUFileBuffered *s;
 
@@ -271,12 +270,12 @@ QEMUFile *qemu_fopen_ops_buffered(MigrationState *migration_state)
 
     s->migration_state = migration_state;
     s->xfer_limit = migration_state->bandwidth_limit / 10;
-    s->complete = false;
+    s->migration_state->complete = false;
 
     s->file = qemu_fopen_ops(s, &buffered_file_ops);
 
+    migration_state->file = s->file;
+
     qemu_thread_create(&s->thread, buffered_file_thread, s,
                        QEMU_THREAD_DETACHED);
-
-    return s->file;
 }

buffered_file.h

@@ -17,6 +17,6 @@
 #include "hw/hw.h"
 #include "migration/migration.h"
 
-QEMUFile *qemu_fopen_ops_buffered(MigrationState *migration_state);
+void qemu_fopen_ops_buffered(MigrationState *migration_state);
 
 #endif

include/migration/migration.h

@@ -45,6 +45,7 @@ struct MigrationState
     int64_t dirty_pages_rate;
     bool enabled_capabilities[MIGRATION_CAPABILITY_MAX];
     int64_t xbzrle_cache_size;
+    bool complete;
 };
 
 void process_incoming_migration(QEMUFile *f);

migration.c

@@ -448,7 +448,7 @@ void migrate_fd_connect(MigrationState *s)
     int ret;
 
     s->state = MIG_STATE_ACTIVE;
-    s->file = qemu_fopen_ops_buffered(s);
+    qemu_fopen_ops_buffered(s);
 
     DPRINTF("beginning savevm\n");
     ret = qemu_savevm_state_begin(s->file, &s->params);