migration: Make dirty_sync_count atomic

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>

3 files changed, 10 insertions, 8 deletions

diff --git a/migration/migration.c b/migration/migration.c
index 4ca2173d85..97c227aa85 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1148,7 +1148,8 @@ static void populate_ram_info(MigrationInfo *info, MigrationState *s)
     info->ram->normal = stat64_get(&ram_counters.normal);
     info->ram->normal_bytes = info->ram->normal * page_size;
     info->ram->mbps = s->mbps;
-    info->ram->dirty_sync_count = ram_counters.dirty_sync_count;
+    info->ram->dirty_sync_count =
+        stat64_get(&ram_counters.dirty_sync_count);
     info->ram->dirty_sync_missed_zero_copy =
         stat64_get(&ram_counters.dirty_sync_missed_zero_copy);
     info->ram->postcopy_requests = ram_counters.postcopy_requests;
diff --git a/migration/ram.c b/migration/ram.c
index b1722b6071..3c13136559 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -764,7 +764,7 @@ static void xbzrle_cache_zero_page(RAMState *rs, ram_addr_t current_addr)
     /* We don't care if this fails to allocate a new cache page
      * as long as it updated an old one */
     cache_insert(XBZRLE.cache, current_addr, XBZRLE.zero_target_page,
-                 ram_counters.dirty_sync_count);
+                 stat64_get(&ram_counters.dirty_sync_count));
 }
 
 #define ENCODING_FLAG_XBZRLE 0x1
@@ -790,13 +790,13 @@ static int save_xbzrle_page(RAMState *rs, PageSearchStatus *pss,
     int encoded_len = 0, bytes_xbzrle;
     uint8_t *prev_cached_page;
     QEMUFile *file = pss->pss_channel;
+    uint64_t generation = stat64_get(&ram_counters.dirty_sync_count);
 
-    if (!cache_is_cached(XBZRLE.cache, current_addr,
-                         ram_counters.dirty_sync_count)) {
+    if (!cache_is_cached(XBZRLE.cache, current_addr, generation)) {
         xbzrle_counters.cache_miss++;
         if (!rs->last_stage) {
             if (cache_insert(XBZRLE.cache, current_addr, *current_data,
-                             ram_counters.dirty_sync_count) == -1) {
+                             generation) == -1) {
                 return -1;
             } else {
                 /* update *current_data when the page has been
@@ -1209,7 +1209,7 @@ static void migration_bitmap_sync(RAMState *rs)
     RAMBlock *block;
     int64_t end_time;
 
-    ram_counters.dirty_sync_count++;
+    stat64_add(&ram_counters.dirty_sync_count, 1);
 
     if (!rs->time_last_bitmap_sync) {
         rs->time_last_bitmap_sync = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
@@ -1246,7 +1246,8 @@ static void migration_bitmap_sync(RAMState *rs)
         rs->bytes_xfer_prev = stat64_get(&ram_counters.transferred);
     }
     if (migrate_use_events()) {
-        qapi_event_send_migration_pass(ram_counters.dirty_sync_count);
+        uint64_t generation = stat64_get(&ram_counters.dirty_sync_count);
+        qapi_event_send_migration_pass(generation);
     }
 }
 
diff --git a/migration/ram.h b/migration/ram.h
index bb52632424..8c0d07c43a 100644
--- a/migration/ram.h
+++ b/migration/ram.h
@@ -42,7 +42,7 @@
  */
 typedef struct {
     int64_t dirty_pages_rate;
-    int64_t dirty_sync_count;
+    Stat64 dirty_sync_count;
     Stat64 dirty_sync_missed_zero_copy;
     Stat64 downtime_bytes;
     Stat64 duplicate;