[PATCH v2 02/11] migration: Make multifd_bytes atomic

[Juan Quintela <quintela@redhat.com>]

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

Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 migration/ram.h       | 1 +
 migration/migration.c | 4 ++--
 migration/multifd.c   | 4 ++--
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/migration/ram.h b/migration/ram.h
index 81cbb0947c..3c1de6aedf 100644
--- a/migration/ram.h
+++ b/migration/ram.h
@@ -50,6 +50,7 @@ typedef struct {
     Stat64 duplicate;
     Stat64 normal;
     Stat64 postcopy_bytes;
+    Stat64 multifd_bytes;
 } MigrationAtomicStats;
 
 extern MigrationAtomicStats ram_atomic_counters;
diff --git a/migration/migration.c b/migration/migration.c
index 644c61e91d..d261c7d16d 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1058,7 +1058,7 @@ 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_atomic_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;
@@ -3659,7 +3659,7 @@ 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_atomic_counters.multifd_bytes);
 }
 
 static void migration_calculate_complete(MigrationState *s)
diff --git a/migration/multifd.c b/migration/multifd.c
index 20a81cd7f2..49fa76e5e1 100644
--- a/migration/multifd.c
+++ b/migration/multifd.c
@@ -431,8 +431,8 @@ 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_atomic_counters.multifd_bytes, transferred);
     stat64_add(&ram_atomic_counters.transferred, transferred);
     qemu_sem_post(&p->sem);
 
@@ -623,8 +623,8 @@ 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_atomic_counters.multifd_bytes, p->packet_len);
         stat64_add(&ram_atomic_counters.transferred, p->packet_len);
         qemu_sem_post(&p->sem);
 
-- 
2.39.1