migration: Make multifd_bytes atomic

In the spirit of:

commit 394d323bc3451e4d07f13341cb8817fac8dfbadd
Author: Peter Xu <peterx@redhat.com>
Date:   Tue Oct 11 17:55:51 2022 -0400

    migration: Use atomic ops properly for page accountings

Reviewed-by: David Edmondson <david.edmondson@oracle.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

3 files changed, 5 insertions, 5 deletions

diff --git a/migration/migration.c b/migration/migration.c
index 10483f3cab..c3debe71f6 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1153,7 +1153,7 @@ static void populate_ram_info(MigrationInfo *info, MigrationState *s)
             ram_counters.dirty_sync_missed_zero_copy;
     info->ram->postcopy_requests = ram_counters.postcopy_requests;
     info->ram->page_size = page_size;
-    info->ram->multifd_bytes = ram_counters.multifd_bytes;
+    info->ram->multifd_bytes = stat64_get(&ram_counters.multifd_bytes);
     info->ram->pages_per_second = s->pages_per_second;
     info->ram->precopy_bytes = ram_counters.precopy_bytes;
     info->ram->downtime_bytes = ram_counters.downtime_bytes;
@@ -3778,7 +3778,7 @@ static MigThrError migration_detect_error(MigrationState *s)
 static uint64_t migration_total_bytes(MigrationState *s)
 {
     return qemu_file_total_transferred(s->to_dst_file) +
-        ram_counters.multifd_bytes;
+        stat64_get(&ram_counters.multifd_bytes);
 }
 
 static void migration_calculate_complete(MigrationState *s)
diff --git a/migration/multifd.c b/migration/multifd.c
index 6ef3a27938..1c992abf53 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -432,9 +432,9 @@ static int multifd_send_pages(QEMUFile *f)
     p->pages = pages;
     transferred = ((uint64_t) pages->num) * p->page_size + p->packet_len;
     qemu_file_acct_rate_limit(f, transferred);
-    ram_counters.multifd_bytes += transferred;
     qemu_mutex_unlock(&p->mutex);
     stat64_add(&ram_counters.transferred, transferred);
+    stat64_add(&ram_counters.multifd_bytes, transferred);
     qemu_sem_post(&p->sem);
 
     return 1;
@@ -627,9 +627,9 @@ int multifd_send_sync_main(QEMUFile *f)
         p->flags |= MULTIFD_FLAG_SYNC;
         p->pending_job++;
         qemu_file_acct_rate_limit(f, p->packet_len);
-        ram_counters.multifd_bytes += p->packet_len;
         qemu_mutex_unlock(&p->mutex);
         stat64_add(&ram_counters.transferred, p->packet_len);
+        stat64_add(&ram_counters.multifd_bytes, p->packet_len);
         qemu_sem_post(&p->sem);
     }
     for (i = 0; i < migrate_multifd_channels(); i++) {
diff --git a/migration/ram.h b/migration/ram.h
index 7c026b5242..ed70391317 100644
--- a/migration/ram.h
+++ b/migration/ram.h
@@ -46,7 +46,7 @@ typedef struct {
     uint64_t dirty_sync_missed_zero_copy;
     uint64_t downtime_bytes;
     Stat64 duplicate;
-    uint64_t multifd_bytes;
+    Stat64 multifd_bytes;
     Stat64 normal;
     Stat64 postcopy_bytes;
     int64_t postcopy_requests;