Reviewed all task exit logic. For pthread_exit() moved some logic higher in the exit sequence that could be required to block. For lower level logic kicked off by _exit(), add logic to prevent blocking when the task is not in a healthy state.

8 files changed, 174 insertions, 199 deletions

diff --git a/nuttx/ChangeLog b/nuttx/ChangeLog
index 8b81b1989..1f9f200ed 100644
--- a/nuttx/ChangeLog
+++ b/nuttx/ChangeLog
@@ -563,7 +563,7 @@
 	  types.
 
 0.3.19 2008-11-26 Gregory Nutt <gnutt@nuttx.org>
-	* Add poll() and select() APIs (in the initial check-in, these work only with character devices) 
+	* Add poll() and select() APIs (in the initial check-in, these work only with character devices)
 	* Add poll() methods to /dev/null, /dev/zero, pipes, fifos, and serial drivers.
 	* Add examples/poll for testing poll() and select()
 	* Fix hostile behavior of getc, fgetc, getchar, etc.: the serial driver was waiting for a
@@ -612,8 +612,8 @@
 
 0.4.2 2009-02-28 Gregory Nutt <gnutt@nuttx.org>
 
-	* M16C: Add support for the Renesas M16C MCU and the SKP16C26 StarterKit. However, 
-	  the target cannot be built because the GNU m16c-elf-ld link fails with 
+	* M16C: Add support for the Renesas M16C MCU and the SKP16C26 StarterKit. However,
+	  the target cannot be built because the GNU m16c-elf-ld link fails with
 	  the following message:
 
 		m32c-elf-ld: BFD (GNU Binutils) 2.19 assertion fail /home/Owner/projects/nuttx/buildroot/toolchain_build_m32c/binutils-2.19/bfd/elf32-m32c.c:482
@@ -711,7 +711,7 @@
 	  -R .note.gnu.build-id -R .comment"  This has been fixed in arch/arm/src/Makefile,
 	  but other architectures may have the same problem.  Thanks to Dave Marples
 	  for verifying this.
-	* configs/eagle100/ostest: Added support for the MicroMint Eagle100 board. 
+	* configs/eagle100/ostest: Added support for the MicroMint Eagle100 board.
 	  This board has a Luminary LM3S6918 Cortex-M3. Added a configuration to build
 	  examples/ostest.
 	* arch/arm/src/lpc214x: Add configuration option to enable fast GPIO (vs.
@@ -1045,7 +1045,7 @@
 	* configs/sam3u-3k/ostest: Completed verification of the basic NuttX
 	  OS test for the SAM3U.
 	* arch/arm/src/common/up_createstack: stack was always been cleared
-	  when it was allocated.  This is a good feature for monitoring the 
+	  when it was allocated.  This is a good feature for monitoring the
 	  stack during debug, but really hurts thread start-up performance.
 	  Clearing is now done if CONFIG_DEBUG=y only.  Changes was only made
 	  for arm, but really should be made for all architectures.
@@ -1186,7 +1186,7 @@
 	* examples/nsh/nsh_telnetd.c: Fix compilation errors that happen
 	  when both DHCPC and TELNETD are enabled in the Nuttshell.
 	* graphics/nxglib/fb/nxglib_moverectangle.c: Fix a logic error
-	  that caused an uninitialized variable warning.  I still don't 
+	  that caused an uninitialized variable warning.  I still don't
 	  have a test to prove that the changes are correct.
 	* configs/olimex-lpc2378: Add support for the CodeSourcery toolchain
 	  under Linux (contributed by Alan Carvalho de Assis).
@@ -1669,14 +1669,14 @@
 	* arch/arm/src/lpc17xx/lpc17_gpioint.c: Correct errors in logic that maps
 	  and IRQ number into a register bit number.
 	* Makefile: Fix an error introduced in the top-level Makefile in NuttX-6.1.
-	  This error only shows up if you have a /tftpboot directory.  Then the 
+	  This error only shows up if you have a /tftpboot directory.  Then the
 	  make will fail with an obscure error about not being able to stat pass2.
 	* configs/lpcxpresso-lpc1768/nsh: Add an NSH configuration for the
 	  LPCXpresso board.
 	* configs/*/ld.script: Removed 'sh_link not set for section .ARM.edix' for
 	  a few of the builds.  In you have this warning, it can be removed with the
 	  following change to the ld.script file:
-	  
+	
 		+ __exidx_start = ABSOLUTE(.);
 		.ARM.exidx : {
 		-     __exidx_start = ABSOLUTE(.);
@@ -1802,7 +1802,7 @@
 	  already disconnected and the buffered data is stranded.  Now, recvfrom
 	  will continue to return success after the socket is disconnected until
 	  the readahead buffer is drained.
-	* olimex-lp1766stk/ftpc/defconfig: Many configurations have the MTU 
+	* olimex-lp1766stk/ftpc/defconfig: Many configurations have the MTU
 	  (CONFIG_NET_BUFSIZE) set to very small numbers, less then the minimum
 	  MTU size that must be supported -- 576. This can cause problems in
 	  some networks:  CONFIG_NET_BUFSIZE should be set to at least 576 in
@@ -1915,7 +1915,7 @@
 	  new file; Implement VFAT long file name support.
 	* fs/fat/fat_fat32dirent.c:  The configuration CONFIG_FAT_LCNAMES has
 	  been around for some time but never tested until now.  This setting
-	  will mimic the NT 8.3 file name behavior:  File names or extensions 
+	  will mimic the NT 8.3 file name behavior:  File names or extensions
 	  may be all upper or all lower case (but not mixed).  If
 	  CONFIG_FAT_LCNAMES is not selected, all filenames are strictly upper
 	  case.
@@ -1943,7 +1943,7 @@
 	  program.  The bdf-converter program be used to convert fonts in Bitmap
 	  Distribution Format (BDF) into fonts that can be used in the NX graphics
 	  system.
-	* include/nuttx/nx:  Move all NX header files from include/nuttx to 
+	* include/nuttx/nx:  Move all NX header files from include/nuttx to
 	  include/nuttx/nx.
 	* drivers/usbdev/usbdev_usbstorage.c and arch/arm/src/stm32/stm32_usbdev.c:
 	  Correct a memory leak when the USB mass storage driver is connected and
@@ -2051,7 +2051,7 @@
 	* arch/*/src/Makefile:  Use of -print-libgcc-file-name to get path to
 	  libgcc.a may select the wrong libgcc.a if a multilib toolchain (like
 	  CodeSourcery) is used. This can be a serious problem and can cause
-	  crashes on Cortex-M3 if the ARM libgcc is used, for example.  The fix 
+	  crashes on Cortex-M3 if the ARM libgcc is used, for example.  The fix
 	  is to include ARCHCPUFLAGS on the gcc command line when asking it to
 	  -print-libgcc-file-name.
 	* lib/time/lib_gmtimer.c:  Correct several calculations that could lead
@@ -2280,7 +2280,7 @@
 	  the particular condition that revealed the bug occurred.  My impression is
 	  that this latter bugfix also fixes some STM32 USB performance problems.
 	* configs/hymini-stm32v: A configuration for the HY-Mini STM32v board contributed
-	  by Laurent Latil.  These changes also include support for the STM32F103VCT6. 
+	  by Laurent Latil.  These changes also include support for the STM32F103VCT6.
 	* arch/configs/stm3240g-eval/src/up_pwm.c:  Add hooks needed to use the new
 	  apps/examples/pwm test of the STM32 PWM  driver.
 	* drivers/mtd/mp25x.c:  Add ability to use different SPI modes and different
@@ -2394,7 +2394,7 @@
 	  common upper half battery driver.
 	* drivers/power/max1704x.c:  Add a driver for MAX17040x battery "fuel gauge"
 	* arch/arm/src/stm32/stm32_i2c.c: Add support for I2C3
-	* drivers/usbdev/: Lots of name changes: cdc_serial->cdcacm, usbstrg->usbmsc, 
+	* drivers/usbdev/: Lots of name changes: cdc_serial->cdcacm, usbstrg->usbmsc,
 	  usbser->pl2303
 	* drivers/usbdev/composite: Fleshed out support for a composite USB device.
 	* drivers/stm3210e-eval/composite and drivers/stm3210e-eval/src/up_composite.c:
@@ -2704,7 +2704,7 @@
 	  platform did not make into all of the Make.defs files.
 	* graphics/nxmu/nx_move.c:  Wrong opcode was being used in the server message;
 	  Also there was an error in the offset calculation.
-	* graphics/nxglib/fb/nxglib_moverectangle.c:  Offset argument is really a 
+	* graphics/nxglib/fb/nxglib_moverectangle.c:  Offset argument is really a
 	  position, not an offset.
 	* graphics/nxtk/nxtk_drawframe.c:  Framed windows are now drawn in three
 	  colors (instead of just two).
@@ -2938,7 +2938,7 @@
 	  is slowly evolving in these directories.
 	* configs/stm3210e-eval/pm:  Add a new configuration for testing STM32 power
 	  management.
-	* configs/stm3210e-eval/scripts:  Moved all of the duplicate ST3210-EVAL 
+	* configs/stm3210e-eval/scripts:  Moved all of the duplicate ST3210-EVAL
 	  linker scripts into one set of linker scripts at this location.
 	* configs/stm3210e-eval/src/up_buttons.c, up_lcd.c, and up_pm.c:  New logic
 	  for testing STM32 power management.
@@ -3139,7 +3139,7 @@
 	  customize the behavior of NSH.
 	* arch/arm/src/stm32/chip/stm32f1*_pinmap.h: STM32 CAN TX/RX pins reversed;
 	  inconsistent conditional compilation.  Reported by Max Holtzberg.
-	* arch/arm/*/stm32:  Add support for STM32 F107 "Connectivity Line" 
+	* arch/arm/*/stm32:  Add support for STM32 F107 "Connectivity Line"
 	  Ethernet (contributed by Max Holtzberg).
 	* configs/olimex-stm32-p107:  Add board support for the Olimiex STM32-P107
 	   board (contributed by Max Holtzberg).
@@ -3317,7 +3317,7 @@
 	  to allocate the block driver I/O buffers.
 	* CONFIG_NET_ENC28J60 renamed CONFIG_ENC28J60 to be consistent
 	  in all places.
-	* drivers/enc28j60.c, include/nuttx/net/enc28j60.h, and 
+	* drivers/enc28j60.c, include/nuttx/net/enc28j60.h, and
 	  olimex-strp711/src/up_enc28j60.c:  No longer passes IRQ number
 	  as a parameter.  Instead now passes a call table to manage
 	  ENC28J60 GPIO interrupts.  That is because GPIO interrupts are
@@ -3630,7 +3630,7 @@
 	  just needs re-implemented.
 	* configs/mirtoo: Update Mirtoo pin definitions for Release 2.  Provided
 	  by Konstantin Dimitrov.
-	* Fixed an uninitialized variable in the file system that can cause 
+	* Fixed an uninitialized variable in the file system that can cause
 	  assertions if DEBUG on (contributed by Lorenz Meier).
 	* Config.mk:  Defined DELIM to be either / or \, depending upon
 	  CONFIG_WINDOWS_NATIVE.  This will allow me to eliminate a lot of
@@ -4088,7 +4088,7 @@
 	  switched to SPI mode for first time.  Having a pull-up resistor on
 	  MISO may avoid this problem, but this patch makes it work also
 	  without pull-up.  From Petteri Aimonen.
-	* fs/fat/fs_fat32.c: Fix a compilation error when FAT_DMAMEMORY=y. 
+	* fs/fat/fs_fat32.c: Fix a compilation error when FAT_DMAMEMORY=y.
 	  From Petteri Aimonen.
 	* arch/arm/src/stm32/chip/stm32_spi.h: STM32F4 max SPI clock freq is
 	  37.5 MHz.  Patch from Petteri Aimonen.
@@ -4599,4 +4599,10 @@
 	* tools/kconfig2html.c:  Improve behavior of Expand/Collapse
 	  Table of Contents; Handle errors in parsing of strings and in
 	  some uninitialized variables.  Add an option to use jQuery.
-	* tools/mkconfigvar.sh: Fix make target.
+	* tools/mkconfigvar.sh: Fix make target (2014-4-23).
+	* sched/exit.c, pthread_exit.c, task_exit.c, task_delete,c and
+	  task_exithook.c:  For pthread_exit(), move some logic to an early
+	  point in the exit sequence where the task may need to block.  Add
+	  conditional logic in the lower end of the eixt logic kicked off by
+	  _exit() to prohibit blocking after the task has been torn down and is
+	  no longer cabable of blocking (2014-4-23).
diff --git a/nuttx/include/nuttx/usb/usbdev.h b/nuttx/include/nuttx/usb/usbdev.h
index 1270fe13a..7d47055d7 100644
--- a/nuttx/include/nuttx/usb/usbdev.h
+++ b/nuttx/include/nuttx/usb/usbdev.h
@@ -289,8 +289,8 @@ struct usbdev_s
 {
   const struct usbdev_ops_s *ops; /* Access to hardware specific features */
   struct usbdev_ep_s *ep0;        /* Endpoint zero */
-  uint8_t  speed;                 /* Current speed of the host connection */
-  uint8_t  dualspeed:1;           /* 1:supports high and full speed operation */
+  uint8_t speed;                  /* Current speed of the host connection */
+  uint8_t dualspeed:1;            /* 1:supports high and full speed operation */
 };
 
 /* USB Device Class Implementations *************************************************/
diff --git a/nuttx/sched/exit.c b/nuttx/sched/exit.c
index 487748d3c..b88c84ec3 100644
--- a/nuttx/sched/exit.c
+++ b/nuttx/sched/exit.c
@@ -100,10 +100,11 @@ void exit(int status)
 
   /* Perform common task termination logic.  This will get called again later
    * through logic kicked off by _exit().  However, we need to call it before
-   * calling _exit() in order to handle atexit() and on_exit() callbacks.
+   * calling _exit() in order to handle atexit() and on_exit() callbacks and
+   * so that we can flush buffered I/O (both of which may required suspending).
    */
 
-  task_exithook(tcb, status);
+  task_exithook(tcb, status, false);
 
   /* Then "really" exit.  Only the lower 8 bits of the exit status are used. */
 
diff --git a/nuttx/sched/os_internal.h b/nuttx/sched/os_internal.h
index bbfce9696..d13eb9cad 100644
--- a/nuttx/sched/os_internal.h
+++ b/nuttx/sched/os_internal.h
@@ -265,7 +265,8 @@ int  task_schedsetup(FAR struct task_tcb_s *tcb, int priority, start_t start,
                      main_t main, uint8_t ttype);
 int  task_argsetup(FAR struct task_tcb_s *tcb, FAR const char *name, FAR char * const argv[]);
 int  task_exit(void);
-void task_exithook(FAR struct tcb_s *tcb, int status);
+int  task_terminate(pid_t pid, bool nonblocking);
+void task_exithook(FAR struct tcb_s *tcb, int status, bool nonblocking);
 void task_recover(FAR struct tcb_s *tcb);
 
 #ifndef CONFIG_CUSTOM_STACK
diff --git a/nuttx/sched/pthread_exit.c b/nuttx/sched/pthread_exit.c
index db51be78f..da4a6d149 100644
--- a/nuttx/sched/pthread_exit.c
+++ b/nuttx/sched/pthread_exit.c
@@ -1,7 +1,7 @@
 /************************************************************************
  * sched/pthread_exit.c
  *
- *   Copyright (C) 2007, 2009, 2011-2012 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007, 2009, 2011-2013 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -49,6 +49,7 @@
 
 #include <nuttx/arch.h>
 
+#include "os_internal.h"
 #include "pthread_internal.h"
 
 /************************************************************************
@@ -93,7 +94,7 @@
 
 void pthread_exit(FAR void *exit_value)
 {
-  int error_code = (int)((intptr_t)exit_value);
+  struct tcb_s *tcb = (struct tcb_s*)g_readytorun.head;
   int status;
 
   sdbg("exit_value=%p\n", exit_value);
@@ -115,23 +116,25 @@ void pthread_exit(FAR void *exit_value)
   if (status != OK)
     {
       /* Assume that the join completion failured because this
-       * not really a pthread.  Exit by calling exit() to flush
-       * and close all file descriptors and calling atexit()
-       * functions.
+       * not really a pthread.  Exit by calling exit().
        */
 
-      if (error_code == EXIT_SUCCESS)
-        {
-           error_code = EXIT_FAILURE;
-        }
-
-      exit(error_code);
+      exit(EXIT_FAILURE);
     }
 
+  /* Perform common task termination logic.  This will get called again later
+   * through logic kicked off by _exit().  However, we need to call it before
+   * calling _exit() in order certain operations if this is the last thread
+   * of a task group:  (2) To handle atexit() and on_exit() callbacks and
+   * (2) so that we can flush buffered I/O (which may required suspending).
+   */
+
+  task_exithook(tcb, EXIT_SUCCESS, false);
+
   /* Then just exit, retaining all file descriptors and without
    * calling atexit() functions.
    */
 
-  _exit(error_code);
+  _exit(EXIT_SUCCESS);
 }
 
diff --git a/nuttx/sched/task_delete.c b/nuttx/sched/task_delete.c
index 64830154c..f6a19a790 100644
--- a/nuttx/sched/task_delete.c
+++ b/nuttx/sched/task_delete.c
@@ -1,7 +1,7 @@
 /****************************************************************************
  * sched/task_delete.c
  *
- *   Copyright (C) 2007-2009, 2011-2012 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2011-2013 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -77,30 +77,36 @@
  ****************************************************************************/
 
 /****************************************************************************
- * Name: task_delete
+ * Name: task_terminate
  *
  * Description:
  *   This function causes a specified task to cease to exist. Its  stack and
- *   TCB will be deallocated.  This function is the companion to task_create().
+ *   TCB will be deallocated.  This function is the internal implementation
+ *   of the task_delete() function.  It includes and additional parameter
+ *   to determine if blocking is permitted or not.
  *
- *   The logic in this function only deletes non-running tasks.  If the 'pid'
- *   parameter refers to to the currently runing task, then processing is
- *   redirected to exit().
+ *   This function is the final function called all task termination
+ *   sequences.  task_terminate() is called only from task_delete() (with
+ *   nonblocking == false) and from task_exit() (with nonblocking == true).
  *
- *   Control will still be returned to task_delete() after the exit() logic
- *   finishes.  In fact, this function is the final function called all task
- *   termination sequences.  Here are all possible exit scenarios:
+ *   The path through task_exit() supports the final stops of the exit(),
+ *   _exit(), and pthread_exit
  *
- *   - pthread_exit().  Calls exit()
+ *   - pthread_exit().  Calls _exit()
  *   - exit(). Calls _exit()
  *   - _exit().  Calls task_exit() making the currently running task
- *     non-running then calls task_delete() to terminate the non-running
- *     task.
- *   - task_delete()
+ *     non-running. task_exit then calls task_terminate() (with nonblocking
+ *     == true) to terminate the non-running task.
+ *
+ *   NOTE: that the state of non-blocking is irrelevant when called through
+ *   exit() and pthread_exit().  In those cases task_exithook() has already
+ *   been called with nonblocking == false;
  *
  * Inputs:
  *   pid - The task ID of the task to delete.  A pid of zero
  *         signifies the calling task.
+ *   nonblocking - True: The task is an unhealthy, partially torn down
+ *         state and is not permitted to block.
  *
  * Return Value:
  *   OK on success; or ERROR on failure
@@ -110,25 +116,12 @@
  *
  ****************************************************************************/
 
-int task_delete(pid_t pid)
+int task_terminate(pid_t pid, bool nonblocking)
 {
-  FAR struct tcb_s *rtcb;
   FAR struct tcb_s *dtcb;
   irqstate_t saved_state;
   int ret = ERROR;
 
-  /* Check if the task to delete is the calling task */
-
-  rtcb = (FAR struct tcb_s*)g_readytorun.head;
-  if (pid == 0 || pid == rtcb->pid)
-    {
-      /* If it is, then what we really wanted to do was exit. Note that we
-       * don't bother to unlock the TCB since it will be going away.
-       */
-
-      exit(EXIT_SUCCESS);
-    }
-
   /* Make sure the task does not become ready-to-run while we are futzing with
    * its TCB by locking ourselves as the executing task.
    */
@@ -166,7 +159,7 @@ int task_delete(pid_t pid)
    * I suppose EXIT_SUCCESS is an appropriate return value???
    */
 
-  task_exithook(dtcb, EXIT_SUCCESS);
+  task_exithook(dtcb, EXIT_SUCCESS, nonblocking);
 
   /* Remove the task from the OS's tasks lists. */
 
@@ -192,3 +185,61 @@ int task_delete(pid_t pid)
   return ret;
 }
 
+/****************************************************************************
+ * Name: task_delete
+ *
+ * Description:
+ *   This function causes a specified task to cease to exist. Its  stack and
+ *   TCB will be deallocated.  This function is the companion to task_create().
+ *   This is the version of the function exposed to the user; it is simply
+ *   a wrapper around the internal, task_terminate function.
+ *
+ *   The logic in this function only deletes non-running tasks.  If the 'pid'
+ *   parameter refers to to the currently runing task, then processing is
+ *   redirected to exit().  This can only happen if a task calls task_delete()
+ *   in order to delete itself.
+ *
+ *   In fact, this function (and task_terminate) are the final functions
+ *   called all task termination sequences.  task_delete may be called
+ *   from:
+ *
+ *   - task_restart(),
+ *   - pthread_cancel(),
+ *   - and directly from user code.
+ *
+ *   Other exit paths (exit(), _eixt(), and pthread_exit()) will go through
+ *   task_terminate()
+ *
+ * Inputs:
+ *   pid - The task ID of the task to delete.  A pid of zero
+ *         signifies the calling task.
+ *
+ * Return Value:
+ *   OK on success; or ERROR on failure
+ *
+ *   This function can fail if the provided pid does not correspond to a
+ *   task (errno is not set)
+ *
+ ****************************************************************************/
+
+int task_delete(pid_t pid)
+{
+  FAR struct tcb_s *rtcb;
+
+  /* Check if the task to delete is the calling task */
+
+  rtcb = (FAR struct tcb_s*)g_readytorun.head;
+  if (pid == 0 || pid == rtcb->pid)
+    {
+      /* If it is, then what we really wanted to do was exit. Note that we
+       * don't bother to unlock the TCB since it will be going away.
+       */
+
+      DEBUGASSERT(!nonblocking);
+      exit(EXIT_SUCCESS);
+    }
+
+  /* Then let task_terminate do the heavy lifting */
+
+  return task_terminate(pid, false);
+}
diff --git a/nuttx/sched/task_exit.c b/nuttx/sched/task_exit.c
index aafe65f22..031b22ed8 100644
--- a/nuttx/sched/task_exit.c
+++ b/nuttx/sched/task_exit.c
@@ -70,116 +70,6 @@
  ****************************************************************************/
 
 /****************************************************************************
- * Name: task_cancel_atexit
- *
- * Description:
- *   Cncel any registerd atexit function(s)
- *
- *   This function is called from task_exit() which implements the processor-
- *   independent part of _exit().  _exit() is, in turn, used to implement
- *   the bottom half of exit() and pthread_exit().  These cases are
- *   distinguished as follows:
- *
- *   1) _exit() should be called by user logic only from tasks.  In this
- *      case, atexit() calls will be canceled by this function.
- *   2) If the user calls exit(), the exit() function will call task_exithook()
- *      which will process all pending atexit() call.  In that case, this
- *      function will have no effect.
- *   3) If the user called pthread_exit(), the logic in this function will
- *      do nothing.  Only a task can legitimately called _exit().  atexit
- *      calls will not be cleared.  task_exithook() will be called later (from
- *      task_delete()) and if this is the final thread of the group, any
- *      registered atexit() calls will be performed.
- *
- ****************************************************************************/
-
-#if defined(CONFIG_SCHED_ATEXIT) && !defined(CONFIG_SCHED_ONEXIT)
-static inline void task_cancel_atexit(FAR struct tcb_s *tcb)
-{
-  FAR struct task_group_s *group = tcb->group;
-  DEBUGASSERT(group);
-
-  /* This behavior applies only to tasks that call _exit() */
-
-#ifndef CONFIG_DISABLE_PTHREAD
-  if ((tcb->flags & TCB_FLAG_TTYPE_MASK) != TCB_FLAG_TTYPE_PTHREAD)
-#endif
-    {
-#if defined(CONFIG_SCHED_ATEXIT_MAX) && CONFIG_SCHED_ATEXIT_MAX > 1
-      int index;
-
-      /* Nullify each atexit function pointer */
-
-      for (index = 0; index < CONFIG_SCHED_ATEXIT_MAX; index++)
-        {
-          group->tg_atexitfunc[index] = NULL;
-        }
-#else
-      /* Nullify the atexit function to prevent its reuse. */
-
-      group->tg_atexitfunc = NULL;
-#endif
-    }
-}
-#else
-#  define task_cancel_atexit(tcb)
-#endif
-
-/****************************************************************************
- * Name: task_cancel_onexit
- *
- * Description:
- *   Cancel any registerd on)exit function(s).
- *
- *   This function is called from task_exit() which implements the processor-
- *   independent part of _exit().  _exit() is, in turn, used to implement
- *   the bottom half of exit() and pthread_exit().  These cases are
- *   distinguished as follows:
- *
- *   1) _exit() should be called by user logic only from tasks.  In this
- *      case, on_exit() calls will be canceled by this function.
- *   2) If the user calls exit(), the exit() function will call task_exithook()
- *      which will process all pending on_exit() call.  In that case, this
- *      function will have no effect.
- *   3) If the user called pthread_exit(), the logic in this function will
- *      do nothing.  Only a task can legitimately called _exit().  on_exit
- *      calls will not be cleared.  task_exithook() will be called later (from
- *      task_delete()) and if this is the final thread of the group, any
- *      registered on_exit() calls will be performed.
- *
- ****************************************************************************/
- 
-#ifdef CONFIG_SCHED_ONEXIT
-static inline void task_cancel_onexit(FAR struct tcb_s *tcb)
-{
-  FAR struct task_group_s *group = tcb->group;
-  DEBUGASSERT(group);
-
-  /* This behavior applies only to tasks that call _exit() */
-
-#ifndef CONFIG_DISABLE_PTHREAD
-  if ((tcb->flags & TCB_FLAG_TTYPE_MASK) != TCB_FLAG_TTYPE_PTHREAD)
-#endif
-    {
-#if defined(CONFIG_SCHED_ONEXIT_MAX) && CONFIG_SCHED_ONEXIT_MAX > 1
-      int index;
-
-      /* Nullify each atexit function pointer */
-
-      for (index = 0; index < CONFIG_SCHED_ONEXIT_MAX; index++)
-        {
-          group->tg_onexitfunc[index] = NULL;
-        }
-#else
-      group->tg_onexitfunc = NULL;
-#endif
-    }
-}
-#else
-#  define task_cancel_onexit(tcb)
-#endif
-
-/****************************************************************************
  * Public Functions
  ****************************************************************************/
 
@@ -227,14 +117,6 @@ int task_exit(void)
   (void)sched_removereadytorun(dtcb);
   rtcb = (FAR struct tcb_s*)g_readytorun.head;
 
-  /* Cancel any pending atexit() or on_exit() calls.  These are not performed
-   * when performing _exit().  Different implementations of _exit() may or may
-   * not* flush buffered I/O.  This implemenation *will* flush buffered I/O.
-   */
-
-   task_cancel_atexit(rtcb);
-   task_cancel_onexit(rtcb);
-
   /* We are now in a bad state -- the head of the ready to run task list
    * does not correspond to the thread that is running.  Disabling pre-
    * emption on this TCB and marking the new ready-to-run task as not
@@ -247,10 +129,14 @@ int task_exit(void)
   rtcb->lockcount++;
   rtcb->task_state = TSTATE_TASK_READYTORUN;
 
-  /* Move the TCB to the specified blocked task list and delete it */
+  /* Move the TCB to the specified blocked task list and delete it.  Calling
+   * task_terminate with non-blocking true will suppress atexit() and on-exit()
+   * calls and will cause buffered I/O to fail to be flushed.  The former
+   * is required _exit() behavior; the latter is optional _exit() behavior.
+   */
 
   sched_addblocked(dtcb, TSTATE_TASK_INACTIVE);
-  task_delete(dtcb->pid);
+  task_terminate(dtcb->pid, true);
   rtcb->task_state = TSTATE_TASK_RUNNING;
 
   /* If there are any pending tasks, then add them to the ready-to-run
diff --git a/nuttx/sched/task_exithook.c b/nuttx/sched/task_exithook.c
index 71cc13250..b59f8e5ba 100644
--- a/nuttx/sched/task_exithook.c
+++ b/nuttx/sched/task_exithook.c
@@ -143,7 +143,7 @@ static inline void task_atexit(FAR struct tcb_s *tcb)
  *   Call any registerd on_exit function(s)
  *
  ****************************************************************************/
- 
+
 #ifdef CONFIG_SCHED_ONEXIT
 static inline void task_onexit(FAR struct tcb_s *tcb, int status)
 {
@@ -298,7 +298,7 @@ static inline void task_sigchild(gid_t pgid, FAR struct tcb_s *ctcb, int status)
   DEBUGASSERT(chgrp);
 
   /* Get the parent task group.  It is possible that all of the members of
-   * the parent task group have exited.  This would not be an error.  In 
+   * the parent task group have exited.  This would not be an error.  In
    * this case, the child task group has been orphaned.
    */
 
@@ -508,8 +508,8 @@ static inline void task_exitwakeup(FAR struct tcb_s *tcb, int status)
            *
            * "If more than one thread is suspended in waitpid() awaiting
            *  termination of the same process, exactly one thread will
-           * return the process status at the time of the target process
-           * termination." 
+           *  return the process status at the time of the target process
+           *  termination."
            *
            *  Hmmm.. what do we return to the others?
            */
@@ -528,7 +528,7 @@ static inline void task_exitwakeup(FAR struct tcb_s *tcb, int status)
 
          group->tg_statloc = NULL;
          while (group->tg_exitsem.semcount < 0)
-            { 
+            {
               /* Wake up the thread */
 
               sem_post(&group->tg_exitsem);
@@ -588,14 +588,18 @@ static inline void task_flushstreams(FAR struct tcb_s *tcb)
  *   to-run list.  The following logic is safe because we will not be
  *   returning from the exit() call.
  *
- *   When called from task_delete() we are operating on a different thread;
+ *   When called from task_terminate() we are operating on a different thread;
  *   on the thread that called task_delete().  In this case, task_delete
  *   will have already removed the tcb from the ready-to-run list to prevent
  *   any further action on this task.
  *
+ *   nonblocking will be set true only when we are called from task_terminate()
+ *   via _exit().  In that case, we must be careful to do nothing that can
+ *   cause the cause the thread to block.
+ *
  ****************************************************************************/
 
-void task_exithook(FAR struct tcb_s *tcb, int status)
+void task_exithook(FAR struct tcb_s *tcb, int status, bool nonblocking)
 {
   /* Under certain conditions, task_exithook() can be called multiple times.
    * A bit in the TCB was set the first time this function was called.  If
@@ -608,15 +612,28 @@ void task_exithook(FAR struct tcb_s *tcb, int status)
     }
 
   /* If exit function(s) were registered, call them now before we do any un-
-   * initialization.  NOTE:  In the case of task_delete(), the exit function
-   * will *not* be called on the thread execution of the task being deleted!
+   * initialization.
+   *
+   * NOTES:
+   *
+   * 1. In the case of task_delete(), the exit function will *not* be called
+   *    on the thread execution of the task being deleted!  That is probably
+   *    a bug.
+   * 2. We cannot call the exit functions if nonblocking is requested:  These
+   *    functions might block.
+   * 3. This function will only be called with with non-blocking == true
+   *    only when called through _exit(). _exit() behaviors requires that
+   *    the exit functions *not* be called.
    */
 
-  task_atexit(tcb);
+  if (!nonblocking)
+    {
+      task_atexit(tcb);
 
-  /* Call any registered on_exit function(s) */
+      /* Call any registered on_exit function(s) */
 
-  task_onexit(tcb, status);
+      task_onexit(tcb, status);
+    }
 
   /* If the task was terminated by another task, it may be in an unknown
    * state.  Make some feeble effort to recover the state.
@@ -634,9 +651,19 @@ void task_exithook(FAR struct tcb_s *tcb, int status)
 
   /* If this is the last thread in the group, then flush all streams (File
    * descriptors will be closed when the TCB is deallocated).
+   *
+   * NOTES:
+   * 1. We cannot flush the buffered I/O if nonblocking is requested.
+   *    that might cause this logic to block.
+   * 2. This function will only be called with with non-blocking == true
+   *    only when called through _exit(). _exit() behavior does not
+   *    require that the streams be flushed
    */
 
-  task_flushstreams(tcb);
+  if (!nonblocking)
+    {
+      task_flushstreams(tcb);
+    }
 
   /* Leave the task group.  Perhaps discarding any un-reaped child
    * status (no zombies here!)