From 10c2f7b747bebfbf67b2219330269dcd5721f3d9 Mon Sep 17 00:00:00 2001
From: Lukas Straub <lukasstraub2@web.de>
Date: Thu, 20 Apr 2023 11:47:59 +0200
Subject: [PATCH] ram.c: Dont change param->block in the compress thread

Instead introduce a extra parameter to trigger the compress thread.
Now, when the compress thread is done, we know what RAMBlock and
offset it did compress.

This will be used in the next commits to move save_page_header()
out of compress code.

Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
---
 migration/ram.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/migration/ram.c b/migration/ram.c
index 7bc05fc034..b552a9e538 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -492,6 +492,7 @@ typedef enum CompressResult CompressResult;
 struct CompressParam {
     bool done;
     bool quit;
+    bool trigger;
     CompressResult result;
     QEMUFile *file;
     QemuMutex mutex;
@@ -565,10 +566,10 @@ static void *do_data_compress(void *opaque)
 
     qemu_mutex_lock(&param->mutex);
     while (!param->quit) {
-        if (param->block) {
+        if (param->trigger) {
             block = param->block;
             offset = param->offset;
-            param->block = NULL;
+            param->trigger = false;
             qemu_mutex_unlock(&param->mutex);
 
             result = do_compress_ram_page(param->file, &param->stream,
@@ -1545,6 +1546,7 @@ static inline void set_compress_params(CompressParam *param, RAMBlock *block,
 {
     param->block = block;
     param->offset = offset;
+    param->trigger = true;
 }
 
 static int compress_page_with_multi_thread(RAMBlock *block, ram_addr_t offset)