From 16f296f48932379a89c52f095eae199347f33407 Mon Sep 17 00:00:00 2001
From: Justin Clark-Casey (justincc)
Date: Wed, 15 Sep 2010 21:41:42 +0100
Subject: Instead of locking SOG.Children when a group is being removed from
 the scene, iterate over an unlocked list instead

Previously, deadlock was possible because deleting a group took a SOG.Children lock then an m_entityUpdates.SyncRoot lock in LLClientView
At the same time, a thread starting from LLClientView.ProcessEntityUpdates() could take an m_entityUpdates.SyncRoot lock then later attempt to take a SOG.Children lock in PermissionsModule.GenerateClientFlags() and later on
Taking a children list in SOG appears to be a better solution than changing PermissionsModule to not relook up the prim.  Going the permission modules root would require that all downstream modules not take a SOG.Children lock either
---
 .../Region/Framework/Scenes/SceneObjectGroup.cs    | 32 ++++++++++++----------
 1 file changed, 17 insertions(+), 15 deletions(-)

(limited to 'OpenSim')

diff --git a/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs b/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs
index dc6509d..99c2abf 100644
--- a/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs
+++ b/OpenSim/Region/Framework/Scenes/SceneObjectGroup.cs
@@ -29,6 +29,7 @@ using System;
 using System.Collections.Generic;
 using System.Drawing;
 using System.IO;
+using System.Linq;
 using System.Threading;
 using System.Xml;
 using System.Xml.Serialization;
@@ -1236,26 +1237,27 @@ namespace OpenSim.Region.Framework.Scenes
         /// <param name="silent">If true then deletion is not broadcast to clients</param>
         public void DeleteGroup(bool silent)
         {
+            List<SceneObjectPart> parts;
+
             lock (m_parts)
+                parts = m_parts.Values.ToList();
+            
+            foreach (SceneObjectPart part in parts)
             {
-                foreach (SceneObjectPart part in m_parts.Values)
+                Scene.ForEachScenePresence(delegate(ScenePresence avatar)
                 {
-//                    part.Inventory.RemoveScriptInstances();
-                    Scene.ForEachScenePresence(delegate(ScenePresence avatar)
+                    if (avatar.ParentID == LocalId)
                     {
-                        if (avatar.ParentID == LocalId)
-                        {
-                            avatar.StandUp();
-                        }
+                        avatar.StandUp();
+                    }
 
-                        if (!silent)
-                        {
-                            part.UpdateFlag = 0;
-                            if (part == m_rootPart)
-                                avatar.ControllingClient.SendKillObject(m_regionHandle, part.LocalId);
-                        }
-                    });
-                }
+                    if (!silent)
+                    {
+                        part.UpdateFlag = 0;
+                        if (part == m_rootPart)
+                            avatar.ControllingClient.SendKillObject(m_regionHandle, part.LocalId);
+                    }
+                });
             }
         }
 
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