[PATCH RFC 06/12] migration: Use the new save_query_pending() API directly

[Peter Xu <peterx@redhat.com>]

It's easier to use the new API directly in the migration iterations.  This
also paves way for follow up patches to add new data to report directly to
the iterator function.

When at it, merge the tracepoints too into one.

No functional change intended.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 migration/savevm.h     |  4 ----
 migration/migration.c  | 16 +++++++---------
 migration/savevm.c     | 23 ++---------------------
 migration/trace-events |  1 +
 4 files changed, 10 insertions(+), 34 deletions(-)

diff --git a/migration/savevm.h b/migration/savevm.h
index b116933bce..3c39190fa4 100644
--- a/migration/savevm.h
+++ b/migration/savevm.h
@@ -46,10 +46,6 @@ void qemu_savevm_state_cleanup(void);
 void qemu_savevm_state_complete_postcopy(QEMUFile *f);
 int qemu_savevm_state_complete_precopy(MigrationState *s);
 void qemu_savevm_query_pending(MigPendingData *pending, bool fastpath);
-void qemu_savevm_state_pending_exact(uint64_t *must_precopy,
-                                     uint64_t *can_postcopy);
-void qemu_savevm_state_pending_estimate(uint64_t *must_precopy,
-                                        uint64_t *can_postcopy);
 int qemu_savevm_state_complete_precopy_iterable(QEMUFile *f, bool in_postcopy);
 bool qemu_savevm_state_postcopy_prepare(QEMUFile *f, Error **errp);
 void qemu_savevm_state_end(QEMUFile *f);
diff --git a/migration/migration.c b/migration/migration.c
index dfc60372cf..99c4d09000 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -3204,17 +3204,17 @@ typedef enum {
  */
 static MigIterateState migration_iteration_run(MigrationState *s)
 {
-    uint64_t must_precopy, can_postcopy, pending_size;
     Error *local_err = NULL;
     bool in_postcopy = (s->state == MIGRATION_STATUS_POSTCOPY_DEVICE ||
                         s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE);
     bool can_switchover = migration_can_switchover(s);
+    MigPendingData pending = { };
+    uint64_t pending_size;
     bool complete_ready;
 
     /* Fast path - get the estimated amount of pending data */
-    qemu_savevm_state_pending_estimate(&must_precopy, &can_postcopy);
-    pending_size = must_precopy + can_postcopy;
-    trace_migrate_pending_estimate(pending_size, must_precopy, can_postcopy);
+    qemu_savevm_query_pending(&pending, true);
+    pending_size = pending.precopy_bytes + pending.postcopy_bytes;
 
     if (in_postcopy) {
         /*
@@ -3243,14 +3243,12 @@ static MigIterateState migration_iteration_run(MigrationState *s)
          * during postcopy phase.
          */
         if (pending_size <= s->threshold_size) {
-            qemu_savevm_state_pending_exact(&must_precopy, &can_postcopy);
-            pending_size = must_precopy + can_postcopy;
-            trace_migrate_pending_exact(pending_size, must_precopy,
-                                        can_postcopy);
+            qemu_savevm_query_pending(&pending, false);
+            pending_size = pending.precopy_bytes + pending.postcopy_bytes;
         }
 
         /* Should we switch to postcopy now? */
-        if (must_precopy <= s->threshold_size &&
+        if (pending.precopy_bytes <= s->threshold_size &&
             can_switchover && qatomic_read(&s->start_postcopy)) {
             if (postcopy_start(s, &local_err)) {
                 migrate_error_propagate(s, error_copy(local_err));
diff --git a/migration/savevm.c b/migration/savevm.c
index 6268e68382..b3285d480f 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1779,28 +1779,9 @@ void qemu_savevm_query_pending(MigPendingData *pending, bool fastpath)
         }
         se->ops->save_query_pending(se->opaque, pending);
     }
-}
-
-void qemu_savevm_state_pending_estimate(uint64_t *must_precopy,
-                                        uint64_t *can_postcopy)
-{
-    MigPendingData pending;
-
-    qemu_savevm_query_pending(&pending, true);
-
-    *must_precopy = pending.precopy_bytes;
-    *can_postcopy = pending.postcopy_bytes;
-}
-
-void qemu_savevm_state_pending_exact(uint64_t *must_precopy,
-                                     uint64_t *can_postcopy)
-{
-    MigPendingData pending;
-
-    qemu_savevm_query_pending(&pending, false);
 
-    *must_precopy = pending.precopy_bytes;
-    *can_postcopy = pending.postcopy_bytes;
+    trace_qemu_savevm_query_pending(fastpath, pending->precopy_bytes,
+                                    pending->postcopy_bytes);
 }
 
 void qemu_savevm_state_cleanup(void)
diff --git a/migration/trace-events b/migration/trace-events
index 60e5087e38..5f836a8652 100644
--- a/migration/trace-events
+++ b/migration/trace-events
@@ -7,6 +7,7 @@ qemu_loadvm_state_section_partend(uint32_t section_id) "%u"
 qemu_loadvm_state_post_main(int ret) "%d"
 qemu_loadvm_state_section_startfull(uint32_t section_id, const char *idstr, uint32_t instance_id, uint32_t version_id) "%u(%s) %u %u"
 qemu_savevm_send_packaged(void) ""
+qemu_savevm_query_pending(bool fast, uint64_t precopy, uint64_t postcopy) "fast=%d, precopy=%"PRIu64", postcopy=%"PRIu64
 loadvm_state_switchover_ack_needed(unsigned int switchover_ack_pending_num) "Switchover ack pending num=%u"
 loadvm_state_setup(void) ""
 loadvm_state_cleanup(void) ""
-- 
2.50.1