Changeset 34499 in vbox for trunk/src

Timestamp:

Nov 30, 2010 12:25:04 PM (14 years ago)

Author:

vboxsync

Message:

Main/Medium: prevent VirtualBox object refcount reaching zero while a task is running

File:

• trunk/src/VBox/Main/MediumImpl.cpp (modified) (2 diffs)

trunk/src/VBox/Main/MediumImpl.cpp

@@ -194 +194 @@
           mMediumCaller(aMedium),
           mThread(NIL_RTTHREAD),
-          mProgress(aProgress)
+          mProgress(aProgress),
+          mVirtualBoxCaller(NULL)
     {
         AssertReturnVoidStmt(aMedium, mRC = E_FAIL);
         mRC = mMediumCaller.rc();
+        if (FAILED(mRC))
+            return;
+
+        /* Get strong VirtualBox reference, see below. */
+        VirtualBox *pVirtualBox = aMedium->m->pVirtualBox;
+        mVirtualBox = pVirtualBox;
+        mVirtualBoxCaller.attach(pVirtualBox);
+        mRC = mVirtualBoxCaller.rc();
         if (FAILED(mRC))
             return;
@@ -253 +262 @@
     VDINTERFACE mVDIfProgress;
     VDINTERFACEPROGRESS mVDIfCallsProgress;
+
+    /* Must have a strong VirtualBox reference during a task otherwise the
+     * reference count might drop to 0 while a task is still running. This
+     * would result in weird behavior, including deadlocks due to uninit and
+     * locking order issues. The deadlock often is not detectable because the
+     * uninit uses event semaphores which sabotages deadlock detection. */
+    ComObjPtr<VirtualBox> mVirtualBox;
+    AutoCaller mVirtualBoxCaller;
 };