[PATCH] migration: Fix the minus value for compressed_size

[Zhenzhong Duan]

When update_compress_thread_counts() is called first time, there is
no data stream yet. We see compression_counters.compressed_size
becomes minus value shortly.

Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>
---
 migration/ram.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/migration/ram.c b/migration/ram.c
index dc1de9ddbc68..510db95cdc36 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1443,6 +1443,10 @@ static bool do_compress_ram_page(QEMUFile *f, z_stream 
*stream, RAMBlock *block,
 static void
 update_compress_thread_counts(const CompressParam *param, int bytes_xmit)
 {
+    if (bytes_xmit <= 0) {
+        return;
+    }
+
     ram_transferred_add(bytes_xmit);
 
     if (param->zero_page) {
-- 
2.25.1