migration: Make dirty_sync_count atomic

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

1 files changed, 7 insertions, 6 deletions

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);
     }
 }