Fix race condition between stackmanager and vmmmanager.

Change-Id: Ie3f3fb2050428af1fc398b1577dfc090cd7d26cf
Reviewed-on: http://gfw160.austin.ibm.com:8080/gerrit/591
Tested-by: Jenkins Server
Reviewed-by: MIKE J. JONES <mjjones@us.ibm.com>
Reviewed-by: Melissa J. Connell <missyc@us.ibm.com>
Reviewed-by: Douglas R. Gilbert <dgilbert@us.ibm.com>
Reviewed-by: MATTHEW S. BARTH <msbarth@us.ibm.com>

5 files changed, 22 insertions, 1 deletions

diff --git a/src/include/kernel/stacksegment.H b/src/include/kernel/stacksegment.H
index 2d3474dc6..460a61b49 100644
--- a/src/include/kernel/stacksegment.H
+++ b/src/include/kernel/stacksegment.H
@@ -108,6 +108,8 @@ class StackSegment : public Segment
          * @brief Delete previously created stack for a task.
          *
          * @param i_task - Task ID of task owning the stack.
+         *
+         * @note This function obtains the VMM-subsystem spinlock.
          */
         static void deleteStack(tid_t i_task);
 
diff --git a/src/include/kernel/taskmgr.H b/src/include/kernel/taskmgr.H
index 63aa76484..b38618d22 100644
--- a/src/include/kernel/taskmgr.H
+++ b/src/include/kernel/taskmgr.H
@@ -125,6 +125,9 @@ class TaskManager
          *  @param[in] t - The task to end.
          *  @param[in] retval - Return value from the task.
          *  @param[in] status - TASK_STATUS_* enumeration of how the task ended.
+         *
+         *  @note This function obtains the VMM-subsystem spinlock as part of
+         *        releasing the task stack.
          */
         static void endTask(task_t* t, void* retval, int status);
 
diff --git a/src/include/kernel/vmmmgr.H b/src/include/kernel/vmmmgr.H
index 845066229..3782bb762 100644
--- a/src/include/kernel/vmmmgr.H
+++ b/src/include/kernel/vmmmgr.H
@@ -200,6 +200,7 @@ class VmmManager
 
     public:
         friend class Block;
+        friend class StackSegment;
 
 };
 
diff --git a/src/kernel/msghandler.C b/src/kernel/msghandler.C
index 82dab7f8f..08859633a 100644
--- a/src/kernel/msghandler.C
+++ b/src/kernel/msghandler.C
@@ -22,6 +22,7 @@
 //  IBM_PROLOG_END
 #include <assert.h>
 #include <errno.h>
+#include <util/locked/queue.H>
 #include <kernel/msghandler.H>
 #include <kernel/task.H>
 #include <kernel/cpu.H>
@@ -96,6 +97,11 @@ int MessageHandler::recvMessage(msg_t* i_msg)
     // Lock subsystem spinlock.
     if (iv_lock) iv_lock->lock();
 
+    // List of tasks to end due to errors.
+    //     Ending the task must happen outside of the spinlock due to
+    //     requirements of TaskManager::endTask.
+    Util::Locked::Queue<task_t> endTaskList;
+
     // Get <key, rc> from response.
     MessageHandler_Pending::key_type key =
         reinterpret_cast<MessageHandler_Pending::key_type>(i_msg->data[0]);
@@ -141,7 +147,7 @@ int MessageHandler::recvMessage(msg_t* i_msg)
             // Unsuccessful, unhandled response.  Kill task.
             printk("Unhandled msg rc %d for key %p on task %d @ %p\n",
                    msg_rc, key, deferred_task->tid, deferred_task->context.nip);
-            TaskManager::endTask(deferred_task, NULL, TASK_STATUS_CRASHED);
+            endTaskList.insert(deferred_task);
         }
         else if (CONTINUE_DEFER == rc)
         {
@@ -157,6 +163,11 @@ int MessageHandler::recvMessage(msg_t* i_msg)
     // Finished handling the response, unlock subsystem.
     if (iv_lock) iv_lock->unlock();
 
+    while(task_t* end_task = endTaskList.remove())
+    {
+        TaskManager::endTask(end_task, NULL, TASK_STATUS_CRASHED);
+    }
+
     // Release memory for message (created from sendMsg).
     delete(i_msg);
 
diff --git a/src/kernel/stacksegment.C b/src/kernel/stacksegment.C
index 0ea3e24a8..f7ced0f1f 100644
--- a/src/kernel/stacksegment.C
+++ b/src/kernel/stacksegment.C
@@ -149,6 +149,8 @@ void* StackSegment::_createStack(tid_t i_task)
 
 void StackSegment::_deleteStack(tid_t i_task)
 {
+    VmmManager::getLock()->lock();
+
     uint64_t l_addr_8mb = i_task * (8*MEGABYTE) + VMM_VADDR_STACK_SEGMENT;
 
     StackBlockNode* l_node = iv_blockList.find(l_addr_8mb);
@@ -159,5 +161,7 @@ void StackSegment::_deleteStack(tid_t i_task)
     delete l_node->block;
     delete l_node;
 
+    VmmManager::getLock()->unlock();
+
     return;
 }