[PATCH 02/17] replay: Fix migration replay_mutex locking

[Nicholas Piggin]

Migration causes a number of events that need to go in the replay
trace, such as vm state transitions. The replay_mutex lock needs to
be held for these.

The simplest approach seems to be just take it up-front when taking
the bql.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 migration/migration.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/migration/migration.c b/migration/migration.c
index 2eb9e50a263..277fca954c1 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -24,6 +24,7 @@
 #include "socket.h"
 #include "sysemu/runstate.h"
 #include "sysemu/sysemu.h"
+#include "sysemu/replay.h"
 #include "sysemu/cpu-throttle.h"
 #include "rdma.h"
 #include "ram.h"
@@ -2518,6 +2519,7 @@ static int postcopy_start(MigrationState *ms, Error 
**errp)
     }
 
     trace_postcopy_start();
+    replay_mutex_lock();
     bql_lock();
     trace_postcopy_start_set_run();
 
@@ -2629,6 +2631,7 @@ static int postcopy_start(MigrationState *ms, Error 
**errp)
     migration_downtime_end(ms);
 
     bql_unlock();
+    replay_mutex_unlock();
 
     if (migrate_postcopy_ram()) {
         /*
@@ -2670,6 +2673,7 @@ fail:
     }
     migration_call_notifiers(ms, MIG_EVENT_PRECOPY_FAILED, NULL);
     bql_unlock();
+    replay_mutex_unlock();
     return -1;
 }
 
@@ -2721,6 +2725,7 @@ static int migration_completion_precopy(MigrationState *s,
 {
     int ret;
 
+    replay_mutex_lock();
     bql_lock();
 
     if (!migrate_mode_is_cpr(s)) {
@@ -2746,6 +2751,7 @@ static int migration_completion_precopy(MigrationState *s,
                                              s->block_inactive);
 out_unlock:
     bql_unlock();
+    replay_mutex_unlock();
     return ret;
 }
 
@@ -3633,6 +3639,7 @@ static void *bg_migration_thread(void *opaque)
 
     trace_migration_thread_setup_complete();
 
+    replay_mutex_lock();
     bql_lock();
 
     if (migration_stop_vm(s, RUN_STATE_PAUSED)) {
@@ -3666,6 +3673,7 @@ static void *bg_migration_thread(void *opaque)
      */
     migration_bh_schedule(bg_migration_vm_start_bh, s);
     bql_unlock();
+    replay_mutex_unlock();
 
     while (migration_is_active()) {
         MigIterateState iter_state = bg_migration_iteration_run(s);
@@ -3695,6 +3703,7 @@ fail:
         migrate_set_state(&s->state, MIGRATION_STATUS_ACTIVE,
                 MIGRATION_STATUS_FAILED);
         bql_unlock();
+        replay_mutex_unlock();
     }
 
 fail_setup:
-- 
2.45.2