replay: flush rr queue before loading the vmstate

Non-empty record/replay queue prevents saving and loading the VM state,
because it includes pending bottom halves and block coroutines.
But when the new VM state is loaded, we don't have to preserve the consistency
of the current state anymore. Therefore this patch just flushes the queue
allowing the coroutines to finish and removes checking for empty rr queue
for load_snapshot function.

Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <160174521762.12451.15752448887893855757.stgit@pasha-ThinkPad-X280>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/include/sysemu/replay.h b/include/sysemu/replay.h
index d6026ed8e51b1a50ada2b2d6399cf1ecf90784fb..c486c3afb2f166e2ec23cb330e97b67b1375b25c 100644 (file)
--- a/include/sysemu/replay.h
+++ b/include/sysemu/replay.h
@@ -149,6 +149,8 @@ void replay_disable_events(void);
 void replay_enable_events(void);
 /*! Returns true when saving events is enabled */
 bool replay_events_enabled(void);
+/* Flushes events queue */
+void replay_flush_events(void);
 /*! Adds bottom half event to the queue */
 void replay_bh_schedule_event(QEMUBH *bh);
 /* Adds oneshot bottom half event to the queue */

diff --git a/migration/savevm.c b/migration/savevm.c
index 0e8dc78684f8b54b115ab8a2246dbe5920bd1b2d..d2e141f7b1d1eefb9f68ff4c5abba715bb948767 100644 (file)
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -2881,12 +2881,6 @@ int load_snapshot(const char *name, Error **errp)
     AioContext *aio_context;
     MigrationIncomingState *mis = migration_incoming_get_current();
 
-    if (!replay_can_snapshot()) {
-        error_setg(errp, "Record/replay does not allow loading snapshot "
-                   "right now. Try once more later.");
-        return -EINVAL;
-    }
-
     if (!bdrv_all_can_snapshot(&bs)) {
         error_setg(errp,
                    "Device '%s' is writable but does not support snapshots",
@@ -2920,6 +2914,12 @@ int load_snapshot(const char *name, Error **errp)
         return -EINVAL;
     }
 
+    /*
+     * Flush the record/replay queue. Now the VM state is going
+     * to change. Therefore we don't need to preserve its consistency
+     */
+    replay_flush_events();
+
     /* Flush all IO requests so they don't interfere with the new state.  */
     bdrv_drain_all_begin();
 

diff --git a/replay/replay-events.c b/replay/replay-events.c
index 302b84043af2643c7ab41f6d13794fe9e56c045d..a1c6bb934e78ef3471631230cee4162d94243cd7 100644 (file)
--- a/replay/replay-events.c
+++ b/replay/replay-events.c
@@ -77,6 +77,10 @@ bool replay_has_events(void)
 
 void replay_flush_events(void)
 {
+    if (replay_mode == REPLAY_MODE_NONE) {
+        return;
+    }
+
     g_assert(replay_mutex_locked());
 
     while (!QTAILQ_EMPTY(&events_list)) {

diff --git a/replay/replay-internal.h b/replay/replay-internal.h
index 2f6145ec7c9190aaddf467216c78ef9d004a1e52..97649ed8d77b0d8785f498c5ae4a26596764e402 100644 (file)
--- a/replay/replay-internal.h
+++ b/replay/replay-internal.h
@@ -149,8 +149,6 @@ void replay_read_next_clock(unsigned int kind);
 void replay_init_events(void);
 /*! Clears internal data structures for events handling */
 void replay_finish_events(void);
-/*! Flushes events queue */
-void replay_flush_events(void);
 /*! Returns true if there are any unsaved events in the queue */
 bool replay_has_events(void);
 /*! Saves events from queue into the file */