replay: don't process events at virtual clock checkpoint

As QEMU becomes more multi-threaded and non-synchronized, checkpoints move from thread to thread. And the event queue that processed at checkpoints should belong to the same thread in both record and replay executions. This patch disables asynchronous event processing at virtual clock checkpoint, because it may be invoked in different threads at record and replay. This patch is temporary fix until the checkpoints are completely refactored. Signed-off-by: Pavel Dovgalyuk <[email protected]> Message-Id: <20181018063345.7433.11678.stgit@pasha-VirtualBox> Signed-off-by: Paolo Bonzini <[email protected]>
dreddy · Oct 19, 2018 · ca9759c · ca9759c
1 parent a8de011
commit ca9759c
Show file tree

Hide file tree

Showing 2 changed files with 9 additions and 1 deletion.
diff --git a/replay/replay-events.c b/replay/replay-events.c
@@ -190,6 +190,7 @@ void replay_save_events(int checkpoint)
 {
     g_assert(replay_mutex_locked());
     g_assert(checkpoint != CHECKPOINT_CLOCK_WARP_START);
+    g_assert(checkpoint != CHECKPOINT_CLOCK_VIRTUAL);
     while (!QTAILQ_EMPTY(&events_list)) {
         Event *event = QTAILQ_FIRST(&events_list);
         replay_save_event(event, checkpoint);

diff --git a/replay/replay.c b/replay/replay.c
@@ -214,7 +214,14 @@ bool replay_checkpoint(ReplayCheckpoint checkpoint)
         /* This checkpoint belongs to several threads.
            Processing events from different threads is
            non-deterministic */
-        if (checkpoint != CHECKPOINT_CLOCK_WARP_START) {
+        if (checkpoint != CHECKPOINT_CLOCK_WARP_START
+            /* FIXME: this is temporary fix, other checkpoints
+                      may also be invoked from the different threads someday.
+                      Asynchronous event processing should be refactored
+                      to create additional replay event kind which is
+                      nailed to the one of the threads and which processes
+                      the event queue. */
+            && checkpoint != CHECKPOINT_CLOCK_VIRTUAL) {
             replay_save_events(checkpoint);
         }
         res = true;