Re: [PATCH v8 2/6] memory: make global_dirty_tracking a bitmask

[Hyman]

在 2021/6/18 23:46, Peter Xu 写道:
On Fri, Jun 18, 2021 at 11:32:03PM +0800, huang...@chinatelecom.cn wrote:
diff --git a/include/exec/memory.h b/include/exec/memory.h
index b114f54..dd2404f 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -55,7 +55,17 @@ static inline void fuzz_dma_read_cb(size_t addr,
  }
  #endif
  
-extern bool global_dirty_log;
+/* Possible bits for global_dirty_log */

s/log/tracking/

[...]

-static void memory_global_dirty_log_do_stop(void)
+static void memory_global_dirty_log_do_stop(unsigned int flags)
  {
-    global_dirty_log = false;
+    assert(flags && !(flags & (~GLOBAL_DIRTY_MASK)));
+    assert((global_dirty_tracking & flags) == flags);
+    global_dirty_tracking &= ~flags;
+
+    trace_global_dirty_changed(global_dirty_tracking);
  
      /* Refresh DIRTY_MEMORY_MIGRATION bit.  */
      memory_region_transaction_begin();
@@ -2691,8 +2699,9 @@ static void memory_global_dirty_log_do_stop(void)
  static void memory_vm_change_state_handler(void *opaque, bool running,
                                             RunState state)
  {
+    unsigned int *flags = (unsigned int *)opaque;

[1]

      if (running) {
-        memory_global_dirty_log_do_stop();
+        memory_global_dirty_log_do_stop(*flags);
  
          if (vmstate_change) {
              qemu_del_vm_change_state_handler(vmstate_change);
@@ -2701,18 +2710,19 @@ static void memory_vm_change_state_handler(void 
*opaque, bool running,
      }
  }
  
-void memory_global_dirty_log_stop(void)
+void memory_global_dirty_log_stop(unsigned int flags)
  {
      if (!runstate_is_running()) {
          if (vmstate_change) {
              return;
          }
          vmstate_change = qemu_add_vm_change_state_handler(
-                                memory_vm_change_state_handler, NULL);
+                                memory_vm_change_state_handler,
+                                (void *)&flags);

If to drop malloc/free, we need to cast it with (void *)flags.  &flags is the
address of the local var, which will lost its meaning after the function
returns..
get it, the callback may almost execute after 
memory_global_dirty_log_stop returns, when it excutes, it cannot get the 
right value of flags. my fault!

Then at [1] it should be "unsigned int flags = (unsigned int)opaque;".