Add some checks: if getpid() or get_errno_ptr() are called very early in the initialization sequence, they would fail

4 files changed, 40 insertions, 11 deletions

diff --git a/nuttx/ChangeLog b/nuttx/ChangeLog
index 2f381cd98..4840987d0 100644
--- a/nuttx/ChangeLog
+++ b/nuttx/ChangeLog
@@ -7158,4 +7158,8 @@
 	  in all configurations that use networking or USB (2014-3-9).
 	* include/nuttx/syslog/syslog.h and ramlog.h:  Move syslog.h and
 	  ramlog.h to include/nutt/syslog (2014-4-10).
+	* sched/errno_getptr.c and getpid.c:  Add some checks.  If these
+	  functions are called early in initialization before the tasking
+	  structures are initialized, they will not behavr properly
+	  (2014-4-10).
 
diff --git a/nuttx/sched/errno_get.c b/nuttx/sched/errno_get.c
index cac041f64..c313e3868 100644
--- a/nuttx/sched/errno_get.c
+++ b/nuttx/sched/errno_get.c
@@ -80,5 +80,3 @@ int get_errno(void)
 {
   return *get_errno_ptr();
 }
-
-
diff --git a/nuttx/sched/errno_getptr.c b/nuttx/sched/errno_getptr.c
index b233b18e4..76123468d 100644
--- a/nuttx/sched/errno_getptr.c
+++ b/nuttx/sched/errno_getptr.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * sched/errno_getptr.c
  *
- *   Copyright (C) 2007, 2008, 2011 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2008, 2011, 2014 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -54,6 +54,12 @@
  * Private Data
  ****************************************************************************/
 
+/* This is a 'dummy' errno value to use in context where there is no valid
+ * errno location to use.  For example, when running from an interrupt handler
+ * or early in initialization when task structures have not yet been
+ * initialized.
+ */
+
 static int g_irqerrno;
 
 /****************************************************************************
@@ -89,10 +95,14 @@ FAR int *get_errno_ptr(void)
        * task at the head of the ready-to-run list is actually running.  It
        * may not be running during very brief times during context switching
        * logic (see, for example, task_exit.c).
+       *
+       * There is also a corner case early in the initialization sequence:
+       * The ready to run list may not yet be initialized and g_readytorun.head
+       * may be NULL.
        */
 
       FAR struct tcb_s *rtcb = (FAR struct tcb_s*)g_readytorun.head;
-      if (rtcb->task_state == TSTATE_TASK_RUNNING)
+      if (rtcb && rtcb->task_state == TSTATE_TASK_RUNNING)
         {
           /* Yes.. the task is running normally.  Return a reference to the
            * thread-private errno in the TCB of the running task.
@@ -113,5 +123,3 @@ FAR int *get_errno_ptr(void)
 
   return &g_irqerrno;
 }
-
-
diff --git a/nuttx/sched/getpid.c b/nuttx/sched/getpid.c
index 259d78091..69e2a9c34 100644
--- a/nuttx/sched/getpid.c
+++ b/nuttx/sched/getpid.c
@@ -1,7 +1,7 @@
 /************************************************************************
  * sched/getpid.c
  *
- *   Copyright (C) 2007, 2009 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2009, 2014 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -44,7 +44,7 @@
 #include "os_internal.h"
 
 /************************************************************************
- * Definitions
+ * Pre-processor Definitions
  ************************************************************************/
 
 /************************************************************************
@@ -77,9 +77,28 @@
 
 pid_t getpid(void)
 {
-  /* Return the task ID from the TCB at the head of the
-   * ready-to-run task list
+  FAR struct tcb_s *rtcb;
+
+  /* Get the the TCB at the head of the ready-to-run task list.  That
+   * will be the currently executing task.  There is an exception to
+   * this:  Verify early in the start-up sequence, the g_readytorun
+   * list may be empty!  This case, of course, the start-up/IDLE thread
+   * with pid == 0 must be running.
+   */
+
+  rtcb = (FAR struct tcb_s *)g_readytorun.head;
+  if (rtcb)
+    {
+      /* Return the task ID from the TCB at the head of the ready-to-run
+       * task list
+       */
+
+      return rtcb->pid;
+    }
+
+  /* We must have been called earlier in the start up sequence from the
+   * start-up/IDLE thread before the g_readytorun list has been initialized.
    */
 
-  return ((FAR struct tcb_s*)g_readytorun.head)->pid;
+  return 0;
 }