=== added file 'mysql-test/t/kill_bug.test'
--- mysql-test/t/kill_bug.test	1970-01-01 00:00:00 +0000
+++ mysql-test/t/kill_bug.test	2010-11-11 14:15:40 +0000
@@ -0,0 +1,31 @@
+--source include/not_embedded.inc
+--source include/have_debug.inc
+--source include/have_debug_sync.inc
+
+connect (new_conn, localhost, root,,);
+let $kill_id = `SELECT CONNECTION_ID()`;
+SET DEBUG_SYNC='before_close_connection SIGNAL disconnect WAIT_FOR kill_cmd EXECUTE 3';
+set session debug="+d,sleep_in_vio_close,info";
+
+--connection default
+eval SET @kill_id = $kill_id;
+SET DEBUG_SYNC='before_kill WAIT_FOR disconnect EXECUTE 3';
+SET DEBUG_SYNC='before_kill_and_after_lock SIGNAL kill_cmd EXECUTE 3';
+set session debug="+d,sleep_in_vio_close,info";
+
+--connection default
+--send KILL @kill_id
+
+--disconnect new_conn;
+
+--connection default
+--reap
+
+let $wait_condition= SELECT COUNT(*) = 0
+FROM information_schema.processlist
+WHERE id = $kill_id;
+--source include/wait_condition.inc
+if (!$success)
+{
+  --die #abort
+}

=== modified file 'sql/sql_class.cc'
--- sql/sql_class.cc	2010-09-06 13:40:55 +0000
+++ sql/sql_class.cc	2010-11-11 14:15:40 +0000
@@ -1203,7 +1203,7 @@
         If we're killing ourselves, we know that we're not blocked, so this
         hack is not used.
       */
-
+      DEBUG_SYNC(this, "before_close_active_vio");
       close_active_vio();
     }
 #endif    

=== modified file 'sql/sql_connect.cc'
--- sql/sql_connect.cc	2010-08-16 12:50:27 +0000
+++ sql/sql_connect.cc	2010-11-11 14:15:40 +0000
@@ -36,6 +36,7 @@
                       // reset_host_errors
 #include "sql_acl.h"  // acl_getroot, NO_ACCESS, SUPER_ACL
 #include "sql_callback.h"
+#include "debug_sync.h"
 
 #if defined(HAVE_OPENSSL) && !defined(EMBEDDED_LIBRARY)
 /*
@@ -1193,7 +1194,8 @@
 	break;
     }
     end_connection(thd);
-   
+    DEBUG_SYNC(thd, "before_close_connection");
+
 end_thread:
     close_connection(thd, 0, 1);
     if (MYSQL_CALLBACK_ELSE(thread_scheduler, end_thread, (thd, 1), 0))

=== modified file 'sql/sql_parse.cc'
--- sql/sql_parse.cc	2010-08-25 10:22:34 +0000
+++ sql/sql_parse.cc	2010-11-11 14:15:40 +0000
@@ -6399,6 +6399,8 @@
   uint error=ER_NO_SUCH_THREAD;
   DBUG_ENTER("kill_one_thread");
   DBUG_PRINT("enter", ("id=%lu only_kill=%d", id, only_kill_query));
+
+  DEBUG_SYNC(thd, "before_kill");
   mysql_mutex_lock(&LOCK_thread_count); // For unlink from list
   I_List_iterator<THD> it(threads);
   while ((tmp=it++))
@@ -6412,6 +6414,7 @@
     }
   }
   mysql_mutex_unlock(&LOCK_thread_count);
+  DEBUG_SYNC(thd, "before_kill_and_after_lock");
   if (tmp)
   {
 

=== modified file 'vio/viosocket.c'
--- vio/viosocket.c	2010-08-16 12:50:27 +0000
+++ vio/viosocket.c	2010-11-11 14:15:40 +0000
@@ -277,6 +277,7 @@
 
  if (vio->type != VIO_CLOSED)
   {
+    DBUG_EXECUTE_IF("sleep_in_vio_close", my_sleep(2000000););
     DBUG_ASSERT(vio->type ==  VIO_TYPE_TCPIP ||
       vio->type == VIO_TYPE_SOCKET ||
       vio->type == VIO_TYPE_SSL);