migration: Take bitmap mutex when completing ram migration

Any call to ram_find_and_save_block() needs to take the bitmap mutex.  We
used to not take it for most of ram_save_complete() because we thought
we're the only one left using the bitmap, but it's not true after the
preempt full patchset applied, since the return path can be taking it too.

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

diff --git a/migration/ram.c b/migration/ram.c
index 8aad17c429b108d9893916c80a08bfc6775bad36..cc72c24c18f72ed8bbf9d8cd8cd2d5af0f7df4d5 100644 (file)
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -3406,6 +3406,7 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
         /* try transferring iterative blocks of memory */
 
         /* flush all remaining blocks regardless of rate limiting */
+        qemu_mutex_lock(&rs->bitmap_mutex);
         while (true) {
             int pages;
 
@@ -3419,6 +3420,7 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
                 break;
             }
         }
+        qemu_mutex_unlock(&rs->bitmap_mutex);
 
         flush_compressed_data(rs);
         ram_control_after_iterate(f, RAM_CONTROL_FINISH);