Implement user-mode work queues

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5712 42af7a65-404d-4744-a932-0658087f49c3

10 files changed, 539 insertions, 144 deletions

diff --git a/nuttx/ChangeLog b/nuttx/ChangeLog
index abfdcf6da..cb29aeb3d 100644
--- a/nuttx/ChangeLog
+++ b/nuttx/ChangeLog
@@ -4255,5 +4255,8 @@
 	  (2013-03-05)
 	* libc/wqueue:  Work queue logic moved from sched/ to libc/wqueue.  It
 	  is not really core OS functionality and this move helps prepare for
-	  user-space work queues.
+	  user-space work queues. (2013-03-05)
+	* libc/wqueue:  Implemented user-space work queues.  These will not
+	  get tested until the next time I attempt a NuttX kernel build.
+	  (2013-03-05).
 
diff --git a/nuttx/TODO b/nuttx/TODO
index 96472bc8f..5f2fcf016 100644
--- a/nuttx/TODO
+++ b/nuttx/TODO
@@ -1,4 +1,4 @@
-NuttX TODO List (Last updated February 5, 2013)
+NuttX TODO List (Last updated March 5, 2013)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 This file summarizes known NuttX bugs, limitations, inconsistencies with 
@@ -6,7 +6,7 @@ standards, things that could be improved, and ideas for enhancements.
 
 nuttx/
 
- (11)  Task/Scheduler (sched/)
+ (10)  Task/Scheduler (sched/)
   (1)  Memory Managment (mm/)
   (3)  Signals (sched/, arch/)
   (2)  pthreads (sched/)
@@ -126,23 +126,6 @@ o Task/Scheduler (sched/)
   Status:      Open
   Priority:    Low -- There is no plan to implement this.
 
-  Title:       USER-SPACE WORK QUEUES
-  Description: There has been some use of work queues that has crept into some
-               user code.  I am thinking of NxWidgets::CNxTimer.  That timer
-               logic was originally implemented (correctly) using POSIX timers,
-               but was re-implemented using timed work.
-
-               The issue is that NxWidgets::CNxTimer is a user-space application
-               but the work queues are an OS internal feature.  This will be a
-               problem for KERNEL builds.  Hooks and definitions have been added
-               in include/nuttx/wqueue.h to support a user-space work queue, but
-               the corresponding logic has not been implemented.
-
-               The work queue logic will need to be moved from sched/ to libc/wqueue/
-  Status:      Open.  No work will probably be done until a functional KERNEL build
-               that includes NxWisges::CNxTimer is needed.
-  Priority:    Medium Low for now
-
   Title:       INCOMPATIBILITES WITH execv() AND execl()
   Description: Simplified 'execl()' and 'execv()' functions are provided by
                NuttX.  NuttX does not support processes and hence the concept
diff --git a/nuttx/include/nuttx/wqueue.h b/nuttx/include/nuttx/wqueue.h
index 67a518008..e76cdfd28 100644
--- a/nuttx/include/nuttx/wqueue.h
+++ b/nuttx/include/nuttx/wqueue.h
@@ -61,6 +61,10 @@
  *   (which runs at the lowest of priority and may not be appropriate
  *   if memory reclamation is of high priority).  If CONFIG_SCHED_WORKQUEUE
  *   is enabled, then the following options can also be used:
+ * CONFIG_SCHED_HPWORK - Build the high priority work queue. To preserve
+ *   legacy behavior, CONFIG_SCHED_HPWORK is assumed to be true in a flat
+ *   build (CONFIG_SCHED_KERNEL=n) but must be defined in kernel mode
+ *   in order to build the high priority work queue.
  * CONFIG_SCHED_WORKPRIORITY - The execution priority of the worker
  *   thread.  Default: 192
  * CONFIG_SCHED_WORKPERIOD - How often the worker thread checks for
@@ -83,23 +87,85 @@
  *   priority worker thread.  Default: CONFIG_IDLETHREAD_STACKSIZE.
  */
 
-#if defined(CONFIG_SCHED_WORKQUEUE) && defined(CONFIG_DISABLE_SIGNALS)
-#  warning "Worker thread support requires signals"
+/* Is this a kernel build (CONFIG_NUTTX_KERNEL=y) */
+
+#ifdef CONFIG_NUTTX_KERNEL
+
+  /* Yes.. kernel worker threads are not built in a kernel build when we are
+   * building the user-space libraries.
+   */
+
+#  ifndef __KERNEL__
+#    undef CONFIG_SCHED_HPWORK
+#    undef CONFIG_SCHED_LPWORK
+
+  /* User-space worker threads are not built in a kernel build when we are
+   * building the kernel-space libraries.
+   */
+
+#  else
+#    undef CONFIG_SCHED_USRWORK
+#  endif
+
+  /* User-space worker threads are not built in a flat build
+   * (CONFIG_NUTTX_KERNEL=n)
+   */
+
+#else
+
+  /* To preserve legacy behavior, CONFIG_SCHED_HPWORK is assumed to be true
+   * in a flat build (CONFIG_SCHED_KERNEL=n) but must be defined in kernel
+   * mode in order to build the high priority work queue.
+   */
+
+#  undef CONFIG_SCHED_HPWORK
+#  undef CONFIG_SCHED_USRWORK
+#  define CONFIG_SCHED_HPWORK 1
 #endif
 
-#ifndef CONFIG_SCHED_WORKPRIORITY
-#  define CONFIG_SCHED_WORKPRIORITY 192
+/* We never build the low priority work queue without building the high
+ * priority work queue.
+ */
+
+#if defined(CONFIG_SCHED_LPWORK) && !defined(CONFIG_SCHED_HPWORK)
+#  error "CONFIG_SCHED_LPWORK defined, but CONFIG_SCHED_HPWORK not defined"
+#  undef CONFIG_SCHED_LPWORK
 #endif
 
-#ifndef CONFIG_SCHED_WORKPERIOD
-#  define CONFIG_SCHED_WORKPERIOD (50*1000) /* 50 milliseconds */
+/* We might not be building any work queue support in this context */
+
+#if !defined(CONFIG_SCHED_HPWORK) && !defined(CONFIG_SCHED_LPWORK) && !defined(CONFIG_SCHED_USRWORK)
+#  undef CONFIG_SCHED_WORKQUEUE
 #endif
 
-#ifndef CONFIG_SCHED_WORKSTACKSIZE
-#  define CONFIG_SCHED_WORKSTACKSIZE CONFIG_IDLETHREAD_STACKSIZE
+#ifdef CONFIG_SCHED_WORKQUEUE
+
+/* We are building work queues... Work queues need signal support */
+
+#if defined(CONFIG_SCHED_WORKQUEUE) && defined(CONFIG_DISABLE_SIGNALS)
+#  warning "Worker thread support requires signals"
 #endif
 
+/* High priority, kernel work queue configuration ***************************/
+
+#ifdef CONFIG_SCHED_HPWORK
+
+#  ifndef CONFIG_SCHED_WORKPRIORITY
+#    define CONFIG_SCHED_WORKPRIORITY 192
+#  endif
+
+#  ifndef CONFIG_SCHED_WORKPERIOD
+#    define CONFIG_SCHED_WORKPERIOD (50*1000) /* 50 milliseconds */
+#  endif
+
+#  ifndef CONFIG_SCHED_WORKSTACKSIZE
+#    define CONFIG_SCHED_WORKSTACKSIZE CONFIG_IDLETHREAD_STACKSIZE
+#  endif
+
+/* Low priority kernel work queue configuration *****************************/
+
 #ifdef CONFIG_SCHED_LPWORK
+
 #  ifndef CONFIG_SCHED_LPWORKPRIORITY
 #    define CONFIG_SCHED_LPWORKPRIORITY 50
 #  endif
@@ -111,44 +177,88 @@
 #  ifndef CONFIG_SCHED_LPWORKSTACKSIZE
 #    define CONFIG_SCHED_LPWORKSTACKSIZE CONFIG_IDLETHREAD_STACKSIZE
 #  endif
-#endif
 
-/* How many worker threads are there? */
+/* The high priority worker thread should be higher priority than the low
+ * priority worker thread.
+ */
 
-#ifdef CONFIG_SCHED_LPWORK
-#  define NWORKERS 2
-#else
-#  define NWORKERS 1
+#if CONFIG_SCHED_LPWORKPRIORITY > CONFIG_SCHED_WORKPRIORITY
+#  warning "The Lower priority worker thread has the higher priority"
 #endif
 
-/* Work queue IDs (indices):
+#endif /* CONFIG_SCHED_LPWORK */
+#endif /* CONFIG_SCHED_HPWORK */
+
+/* User space work queue configuration **************************************/
+
+#ifdef CONFIG_SCHED_USRWORK
+
+#  ifndef CONFIG_SCHED_USRWORKPRIORITY
+#    define CONFIG_SCHED_USRWORKPRIORITY 50
+#  endif
+
+#  ifndef CONFIG_SCHED_USRWORKPERIOD
+#    define CONFIG_SCHED_USRWORKPERIOD (50*1000) /* 50 milliseconds */
+#  endif
+
+#  ifndef CONFIG_SCHED_USRWORKSTACKSIZE
+#    define CONFIG_SCHED_USRWORKSTACKSIZE CONFIG_IDLETHREAD_STACKSIZE
+#  endif
+
+#endif /* CONFIG_SCHED_USRWORK */
+
+/* How many worker threads are there?  In the user-space phase of a kernel
+ * build, there will be no more than one.
  *
- * Kernel Work Queues:
- *   HPWORK: This ID of the high priority work queue that should only be used for
- *   hi-priority, time-critical, driver bottom-half functions.
+ * Work queue IDs (indices):
  *
- *   LPWORK: This is the ID of the low priority work queue that can be used for any
- *   purpose.  if CONFIG_SCHED_LPWORK is not defined, then there is only one kernel
- *   work queue and LPWORK == HPWORK.
+ *   Kernel Work Queues:  There are none and any attempts to use them
+ *     should generate errors.
  *
- * User Work Queue:
- *   USRWORK:  CONFIG_NUTTX_KERNEL and CONFIG_SCHED_USRWORK are defined, then NuttX
- *   will also support a user-accessible work queue.  Otherwise, USRWORK == LPWORK.
+ *   User Work Queue:  Will be available if CONFIG_SCHED_USRWORK is defined
  */
 
-#define HPWORK 0
-#ifdef CONFIG_SCHED_LPWORK
-#  define LPWORK (HPWORK+1)
+#if defined(CONFIG_NUTTX_KERNEL) && !defined(__KERNEL__)
+#  ifdef CONFIG_SCHED_USRWORK
+#    define NWORKERS 1
+#    define USRWORK 0
+#  endif
 #else
-#  define LPWORK HPWORK
-#endif
 
-#if defined(CONFIG_NUTTX_KERNEL) && defined(CONFIG_SCHED_USRWORK)
-#  warning "Feature not implemented"
-#  define USRWORK (LPWORK+1)
-#else
-#  define USRWORK LPWORK
-#endif
+  /* In a flat build (CONFIG_NUTTX_KERNEL=n) or during the kernel phase of
+   * the kernel build, there may be 0, 1, or 2 work queues.
+   *
+   * Work queue IDs (indices):
+   *
+   * Kernel Work Queues:
+   *   HPWORK: This ID of the high priority work queue that should only be
+   *     used for hi-priority, time-critical, driver bottom-half functions.
+   *
+   *   LPWORK: This is the ID of the low priority work queue that can be
+   *     used for any purpose.  if CONFIG_SCHED_LPWORK is not defined, then
+   *     there is only one kernel work queue and LPWORK == HPWORK.
+   *
+   * User Work Queue:
+   *   USRWORK:  In the kernel phase a a kernel build, there should be no
+   *     references to user-space work queues.  That would be an error. 
+   *     Otherwise, in a flat build, user applications will use the lower
+   *     priority work queue (if there is one).
+   */
+
+#  define HPWORK 0
+#  ifdef CONFIG_SCHED_LPWORK
+#    define LPWORK (HPWORK+1)
+#    define NWORKERS 2
+#  else
+#    define LPWORK HPWORK
+#    define NWORKERS 1
+#  endif
+
+#  ifndef CONFIG_NUTTX_KERNEL
+#    define USRWORK LPWORK
+#  endif
+
+#endif /* CONFIG_NUTTX_KERNEL && !__KERNEL__ */
 
 /****************************************************************************
  * Public Types
@@ -202,22 +312,50 @@ extern "C"
  * logic.
  */
 
+#ifdef CONFIG_NUTTX_KERNEL
+
+  /* Play some games in the kernel mode build to assure that different
+   * naming is used for the global work queue data structures.  This may
+   * not be necessary but it safer.
+   */
+
+#  ifdef __KERNEL__
+EXTERN struct wqueue_s g_kernelwork[NWORKERS];
+#    define g_work g_kernelwork
+#  else
+EXTERN struct wqueue_s g_usrwork[NWORKERS];
+#    define g_work g_usrwork
+#  endif
+
+#else /* CONFIG_NUTTX_KERNEL */
+
 EXTERN struct wqueue_s g_work[NWORKERS];
 
+#endif /* CONFIG_NUTTX_KERNEL */
+
 /****************************************************************************
  * Public Function Prototypes
  ****************************************************************************/
 
 /****************************************************************************
- * Name: work_hpthread and work_lpthread
+ * Name: work_hpthread, work_lpthread, and work_usrthread
  *
  * Description:
- *   These are the main worker threads that performs actions placed on the
- *   work lists.  One thread also performs periodic garbage collection (that
- *   is performed by the idle thread if CONFIG_SCHED_WORKQUEUE is not defined).
+ *   These are the worker threads that performs actions placed on the work
+ *   lists.
  *
- *   These entrypoints are referenced by OS internally and should not be
- *   accessed by application logic.
+ *   work_hpthread and work_lpthread:  These are the kernel mode work queues
+ *     (also build in the flat build).  One of these threads also performs
+ *     periodic garbage collection (that is otherwise performed by the idle
+ *     thread if CONFIG_SCHED_WORKQUEUE is not defined).
+ *
+ *     These worker threads are started by the OS during normal bringup.
+ *
+ *   work_usrthread:  This is a user mode work queue.  It must be started
+ *     by application code by calling work_usrstart().
+ *
+ *   All of these entrypoints are referenced by OS internally and should not
+ *   not be accessed by application logic.
  *
  * Input parameters:
  *   argc, argv (not used)
@@ -227,12 +365,37 @@ EXTERN struct wqueue_s g_work[NWORKERS];
  *
  ****************************************************************************/
 
+#ifdef CONFIG_SCHED_HPWORK
 int work_hpthread(int argc, char *argv[]);
+#endif
 
 #ifdef CONFIG_SCHED_LPWORK
 int work_lpthread(int argc, char *argv[]);
 #endif
 
+#ifdef CONFIG_SCHED_USRWORK
+int work_usrthread(int argc, char *argv[]);
+#endif
+
+/****************************************************************************
+ * Name: work_usrstart
+ *
+ * Description:
+ *   Start the user mode work queue.
+ *
+ * Input parameters:
+ *   None
+ *
+ * Returned Value:
+ *   The task ID of the worker thread is returned on success.  A negated
+ *   errno value is returned on failure.
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_SCHED_USRWORK
+int work_usrstart(void);
+#endif
+
 /****************************************************************************
  * Name: work_queue
  *
@@ -324,4 +487,5 @@ int work_signal(int qid);
 #endif
 
 #endif /* __ASSEMBLY__ */
+#endif /* CONFIG_SCHED_WORKQUEUE */
 #endif /* __INCLUDE_NUTTX_WQUEUE_H */
diff --git a/nuttx/libc/Kconfig b/nuttx/libc/Kconfig
index 3aee837c3..a549ced45 100644
--- a/nuttx/libc/Kconfig
+++ b/nuttx/libc/Kconfig
@@ -346,7 +346,118 @@ config ARCH_BZERO
 
 endif
 
-comment "Non-standard Helper Functions"
+comment "Non-standard Library Support"
+
+config SCHED_WORKQUEUE
+	bool "Enable worker thread"
+	default n
+	depends on !DISABLE_SIGNALS
+	---help---
+		Create a dedicated "worker" thread to handle delayed processing from interrupt
+		handlers.  This feature is required for some drivers but, if there are no
+		complaints, can be safely disabled.  The worker thread also performs
+		garbage collection -- completing any delayed memory deallocations from
+		interrupt handlers.  If the worker thread is disabled, then that clean up will
+		be performed by the IDLE thread instead (which runs at the lowest of priority
+		and may not be appropriate if memory reclamation is of high priority).
+
+if SCHED_WORKQUEUE
+
+config SCHED_HPWORK
+	bool "High priority (kernel) worker thread"
+	default y
+	---help---
+		If SCHED_WORKQUEUE is defined, then a single, high priority work queue is
+		created by default.  This high priority worker thread is intended to serve
+		as the "bottom half" for driver interrupt handling.
+
+if SCHED_HPWORK
+config SCHED_WORKPRIORITY
+	int "High priority worker thread priority"
+	default 192
+	---help---
+		The execution priority of the worker thread.  Default: 192
+
+config SCHED_WORKPERIOD
+	int "High priority worker thread period"
+	default 50000
+	---help---
+		How often the worker thread checks for work in units of microseconds.
+		Default: 50*1000 (50 MS).
+
+config SCHED_WORKSTACKSIZE
+	int "High priority worker thread stack size"
+	default 2048
+	depends on SCHED_WORKQUEUE
+	---help---
+		The stack size allocated for the worker thread.  Default: 2K.
+
+config SCHED_LPWORK
+	bool "Low priority (kernel) worker thread"
+	default n
+	---help---
+		If SCHED_WORKQUEUE is defined, then a single work queue is created by
+		default.  If SCHED_LPWORK is also defined then an additional, lower-
+		priority work queue will also be created.  This lower priority work
+		queue is better suited for more extended processing (such as file system
+		clean-up operations)
+
+if SCHED_LPWORK
+
+config SCHED_LPWORKPRIORITY
+	int "Low priority worker thread priority"
+	default 50
+	---help---
+		The execution priority of the lopwer priority worker thread.  Default: 192
+
+config SCHED_LPWORKPERIOD
+	int "Low priority worker thread period"
+	default 50000
+	---help---
+		How often the lower priority worker thread checks for work in units
+		of microseconds. Default: 50*1000 (50 MS).
+
+config SCHED_LPWORKSTACKSIZE
+	int "Low priority worker thread stack size"
+	default 2048
+	---help---
+		The stack size allocated for the lower priority worker thread.  Default: 2K.
+
+endif # SCHED_LPWORK
+endif # SCHED_HPWORK
+
+if NUTTX_KERNEL
+
+config SCHED_USRWORK
+	bool "User mode worker thread"
+	default n
+	---help---
+		User space work queues can also be made available for deferred processing in the NuttX kernel build.
+
+if SCHED_USRWORK
+
+config SCHED_LPWORKPRIORITY
+	int "User mode priority worker thread priority"
+	default 50
+	---help---
+		The execution priority of the lopwer priority worker thread.  Default: 192
+
+config SCHED_LPWORKPERIOD
+	int "User mode worker thread period"
+	default 50000
+	---help---
+		How often the lower priority worker thread checks for work in units
+		of microseconds. Default: 50*1000 (50 MS).
+
+config SCHED_LPWORKSTACKSIZE
+	int "User mode worker thread stack size"
+	default 2048
+	---help---
+		The stack size allocated for the lower priority worker thread.  Default: 2K.
+
+endif # SCHED_USRWORK
+endif # NUTTX_KERNEL
+endif # SCHED_WORKQUEUE
 
 config LIB_KBDCODEC
 	bool "Keyboard CODEC"
diff --git a/nuttx/libc/wqueue/Make.defs b/nuttx/libc/wqueue/Make.defs
index 1a13bcf78..fca63a8a6 100644
--- a/nuttx/libc/wqueue/Make.defs
+++ b/nuttx/libc/wqueue/Make.defs
@@ -39,6 +39,10 @@ ifeq ($(CONFIG_SCHED_WORKQUEUE),y)
 
 CSRCS += work_thread.c work_queue.c work_cancel.c work_signal.c
 
+ifeq ($(CONFIG_NUTTX_KERNEL),y)
+CSRCS += work_usrstart.c
+endif
+
 # Add the wqueue directory to the build
 
 DEPPATH += --dep-path wqueue
diff --git a/nuttx/libc/wqueue/work_thread.c b/nuttx/libc/wqueue/work_thread.c
index 32dff9c8c..febcd0ae8 100644
--- a/nuttx/libc/wqueue/work_thread.c
+++ b/nuttx/libc/wqueue/work_thread.c
@@ -65,10 +65,30 @@
  * Public Variables
  ****************************************************************************/
 
-/* The state of each work queue */
+/* The state of each work queue. */
+
+#ifdef CONFIG_NUTTX_KERNEL
+
+  /* Play some games in the kernel mode build to assure that different
+   * naming is used for the global work queue data structures.  This may
+   * not be necessary but it safer.
+   *
+   * In this case g_work is #define'd to be either g_kernelwork or
+   * g_usrwork in include/nuttx/wqueue.h
+   */
+
+#  ifdef __KERNEL__
+struct wqueue_s g_kernelwork[NWORKERS];
+#  else
+struct wqueue_s g_usrwork[NWORKERS];
+#  endif
+
+#else /* CONFIG_NUTTX_KERNEL */
 
 struct wqueue_s g_work[NWORKERS];
 
+#endif /* CONFIG_NUTTX_KERNEL */
+
 /****************************************************************************
  * Private Variables
  ****************************************************************************/
@@ -181,12 +201,24 @@ static void work_process(FAR struct wqueue_s *wqueue)
  * Public Functions
  ****************************************************************************/
 /****************************************************************************
- * Name: work_hpthread and work_lpthread
+ * Name: work_hpthread, work_lpthread, and work_usrthread
  *
  * Description:
- *   These are the main worker threads that performs actions placed on the
- *   work lists.  One thread also performs periodic garbage collection (that
- *   is performed by the idle thread if CONFIG_SCHED_WORKQUEUE is not defined).
+ *   These are the worker threads that performs actions placed on the work
+ *   lists.
+ *
+ *   work_hpthread and work_lpthread:  These are the kernel mode work queues
+ *     (also build in the flat build).  One of these threads also performs
+ *     periodic garbage collection (that is otherwise performed by the idle
+ *     thread if CONFIG_SCHED_WORKQUEUE is not defined).
+ *
+ *     These worker threads are started by the OS during normal bringup.
+ *
+ *   work_usrthread:  This is a user mode work queue.  It must be started
+ *     by application code by calling work_usrstart().
+ *
+ *   All of these entrypoints are referenced by OS internally and should not
+ *   not be accessed by application logic.
  *
  * Input parameters:
  *   argc, argv (not used)
@@ -196,6 +228,8 @@ static void work_process(FAR struct wqueue_s *wqueue)
  *
  ****************************************************************************/
 
+#ifdef CONFIG_SCHED_HPWORK
+
 int work_hpthread(int argc, char *argv[])
 {
   /* Loop forever */
@@ -224,6 +258,7 @@ int work_hpthread(int argc, char *argv[])
 }
 
 #ifdef CONFIG_SCHED_LPWORK
+
 int work_lpthread(int argc, char *argv[])
 {
   /* Loop forever */
@@ -250,5 +285,26 @@ int work_lpthread(int argc, char *argv[])
 }
 
 #endif /* CONFIG_SCHED_LPWORK */
+#endif /* CONFIG_SCHED_HPWORK */
+
+#ifdef CONFIG_SCHED_USRWORK
+
+int work_usrthread(int argc, char *argv[])
+{
+  /* Loop forever */
+
+  for (;;)
+    {
+      /* Then process queued work.  We need to keep interrupts disabled while
+       * we process items in the work list.
+       */
+
+      work_process(&g_work[USRWORK]);
+    }
+
+  return OK; /* To keep some compilers happy */
+}
+
+#endif /* CONFIG_SCHED_USRWORK */
 
 #endif /* CONFIG_SCHED_WORKQUEUE */
diff --git a/nuttx/libc/wqueue/work_usrstart.c b/nuttx/libc/wqueue/work_usrstart.c
new file mode 100644
index 000000000..b472afc8d
--- /dev/null
+++ b/nuttx/libc/wqueue/work_usrstart.c
@@ -0,0 +1,118 @@
+/****************************************************************************
+ * libc/wqueue/work_usrstart.c
+ *
+ *   Copyright (C) 2013 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sched.h>
+#include <errno.h>
+#include <assert.h>
+#include <debug.h>
+
+#include <nuttx/wqueue.h>
+
+#if defined(CONFIG_SCHED_WORKQUEUE) && defined(CONFIG_SCHED_USRWORK)
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+/****************************************************************************
+ * Name: work_usrstart
+ *
+ * Description:
+ *   Start the user mode work queue.
+ *
+ * Input parameters:
+ *   None
+ *
+ * Returned Value:
+ *   The task ID of the worker thread is returned on success.  A negated
+ *   errno value is returned on failure.
+ *
+ ****************************************************************************/
+
+int work_usrstart(void)
+{
+  int errcode;
+
+  DEBUGASSERT(g_usrwork[USRWORK] == NULL);
+
+  /* Start a lower priority worker thread for other, non-critical continuation
+   * tasks
+   */
+
+  svdbg("Starting user-mode worker thread\n");
+
+  g_usrwork[USRWORK].pid = TASK_CREATE("usrwork",
+                                       CONFIG_SCHED_USRWORKPRIORITY,
+                                       CONFIG_SCHED_USRWORKSTACKSIZE,
+                                       (main_t)work_usrthread,
+                                       (FAR char * const *)NULL);
+
+  errcode = errno;
+  ASSERT(g_usrwork[USRWORK].pid > 0);
+  if (g_usrwork[USRWORK].pid < 0)
+    {
+      sdbg("task_create failed: %d\n", errcode);
+      return -errcode;
+    }
+
+  return g_usrwork[USRWORK].pid;
+}
+
+#endif /* CONFIG_SCHED_WORKQUEUE && CONFIG_SCHED_USRWORK */
diff --git a/nuttx/sched/Kconfig b/nuttx/sched/Kconfig
index 61900f498..b7561ff58 100644
--- a/nuttx/sched/Kconfig
+++ b/nuttx/sched/Kconfig
@@ -245,74 +245,6 @@ config SDCLONE_DISABLE
 	desciptors by task_create() when a new task is started. If
 	set, all sockets will appear to be closed in the new task.
 
-config SCHED_WORKQUEUE
-	bool "Enable worker thread"
-	default n
-	depends on !DISABLE_SIGNALS
-	---help---
-		Create a dedicated "worker" thread to handle delayed processing from interrupt
-		handlers.  This feature is required for some drivers but, if there are no
-		complaints, can be safely disabled.  The worker thread also performs
-		garbage collection -- completing any delayed memory deallocations from
-		interrupt handlers.  If the worker thread is disabled, then that clean up will
-		be performed by the IDLE thread instead (which runs at the lowest of priority
-		and may not be appropriate if memory reclamation is of high priority).
-
-config SCHED_WORKPRIORITY
-	int "Worker thread priority"
-	default 192
-	depends on SCHED_WORKQUEUE
-	---help---
-		The execution priority of the worker thread.  Default: 192
-
-config SCHED_WORKPERIOD
-	int "Worker thread period"
-	default 50000
-	depends on SCHED_WORKQUEUE
-	---help---
-		How often the worker thread checks for work in units of microseconds.
-		Default: 50*1000 (50 MS).
-
-config SCHED_WORKSTACKSIZE
-	int "Worker thread stack size"
-	default 2048
-	depends on SCHED_WORKQUEUE
-	---help---
-		The stack size allocated for the worker thread.  Default: 2K.
-
-config SCHED_LPWORK
-	bool "Enable a lower priority worker thread"
-	default n
-	depends on SCHED_WORKQUEUE
-	---help---
-		If SCHED_WORKQUEUE is defined, then a single work queue is created by
-		default.  If SCHED_LPWORK is also defined then an additional, lower-
-		priority work queue will also be created.  This lower priority work
-		queue is better suited for more extended processing (such as file system
-		clean-up operations)
-
-config SCHED_LPWORKPRIORITY
-	int "Lower priority worker thread priority"
-	default 50
-	depends on SCHED_LPWORK
-	---help---
-		The execution priority of the lopwer priority worker thread.  Default: 192
-
-config SCHED_LPWORKPERIOD
-	int "Lower priority worker thread period"
-	default 50000
-	depends on SCHED_LPWORK
-	---help---
-		How often the lower priority worker thread checks for work in units
-		of microseconds. Default: 50*1000 (50 MS).
-
-config SCHED_LPWORKSTACKSIZE
-	int "Lower priority worker thread stack size"
-	default 2048
-	depends on SCHED_LPWORK
-	---help---
-		The stack size allocated for the lower priority worker thread.  Default: 2K.
-
 config SCHED_WAITPID
 	bool "Enable waitpid() API"
 	default n
diff --git a/nuttx/sched/os_bringup.c b/nuttx/sched/os_bringup.c
index 506de8dc3..2fcb9ff7b 100644
--- a/nuttx/sched/os_bringup.c
+++ b/nuttx/sched/os_bringup.c
@@ -62,11 +62,26 @@
  * Pre-processor Definitions
  ****************************************************************************/
 
-/* If NuttX is built as a separately compiled module, then the the header
+/* If NuttX is built as a separately compiled module, then the config.h header
  * file should contain the address of the user module entry point.  If not
  * then the default entry point is user_start.
  */
 
+/* Customize some strings */
+
+#ifdef CONFIG_SCHED_WORKQUEUE
+#  ifdef CONFIG_SCHED_HPWORK
+#    if defined(CONFIG_SCHED_LPWORK)
+#      define HPWORKNAME "hpwork"
+#      define LPWORKNAME "lpwork"
+#    elif defined(CONFIG_SCHED_USRWORK)
+#      define HPWORKNAME "knlwork"
+#    else
+#      define HPWORKNAME "work"
+#    endif
+#  endif
+#endif
+
 /****************************************************************************
  * Private Types
  ****************************************************************************/
@@ -147,9 +162,15 @@ int os_bringup(void)
    */
 
 #ifdef CONFIG_SCHED_WORKQUEUE
-  svdbg("Starting worker thread\n");
+#ifdef CONFIG_SCHED_HPWORK
 
-  g_work[HPWORK].pid = KERNEL_THREAD("work0", CONFIG_SCHED_WORKPRIORITY,
+#ifdef CONFIG_SCHED_LPWORK
+  svdbg("Starting high-priority kernel worker thread\n");
+#else
+  svdbg("Starting kernel worker thread\n");
+#endif
+
+  g_work[HPWORK].pid = KERNEL_THREAD(HPWORKNAME, CONFIG_SCHED_WORKPRIORITY,
                                      CONFIG_SCHED_WORKSTACKSIZE,
                                      (main_t)work_hpthread, (FAR char * const *)NULL);
   ASSERT(g_work[HPWORK].pid > 0);
@@ -159,14 +180,17 @@ int os_bringup(void)
    */
 
 #ifdef CONFIG_SCHED_LPWORK
-  svdbg("Starting worker thread\n");
 
-  g_work[LPWORK].pid = KERNEL_THREAD("work1", CONFIG_SCHED_LPWORKPRIORITY,
+  svdbg("Starting low-priority kernel worker thread\n");
+
+  g_work[LPWORK].pid = KERNEL_THREAD(LPWORKNAME, CONFIG_SCHED_LPWORKPRIORITY,
                                      CONFIG_SCHED_LPWORKSTACKSIZE,
                                      (main_t)work_lpthread, (FAR char * const *)NULL);
   ASSERT(g_work[LPWORK].pid > 0);
-#endif
-#endif
+
+#endif /* CONFIG_SCHED_LPWORK */
+#endif /* CONFIG_SCHED_HPWORK */
+#endif /* CONFIG_SCHED_WORKQUEUE */
 
   /* Once the operating system has been initialized, the system must be
    * started by spawning the user init thread of execution.  This is the
diff --git a/nuttx/syscall/syscall.csv b/nuttx/syscall/syscall.csv
index 6716e9d6a..5f68697ca 100644
--- a/nuttx/syscall/syscall.csv
+++ b/nuttx/syscall/syscall.csv
@@ -43,8 +43,8 @@
 "prctl","sys/prctl.h", "CONFIG_TASK_NAME_SIZE > 0","int","int","..." 
 "clock_systimer","nuttx/clock.h","!defined(CONFIG_DISABLE_CLOCK)","uint32_t"
 "poll","poll.h","!defined(CONFIG_DISABLE_POLL) && (CONFIG_NSOCKET_DESCRIPTORS > 0 || CONFIG_NFILE_DESCRIPTORS > 0)","int","FAR struct pollfd*","nfds_t","int"
-"posix_spawnp", defined(CONFIG_BINFMT_EXEPATH), "int","FAR pid_t *","FAR const char *","FAR const posix_spawn_file_actions_t *","FAR const posix_spawnattr_t *","FAR char *const []","FAR char *const []"
-"posix_spawn", !defined(CONFIG_BINFMT_EXEPATH), "int","FAR pid_t *","FAR const char *","FAR const posix_spawn_file_actions_t *","FAR const posix_spawnattr_t *","FAR char *const []","FAR char *const []"
+"posix_spawnp","spawn.h","defined(CONFIG_BINFMT_EXEPATH)","int","FAR pid_t *","FAR const char *","FAR const posix_spawn_file_actions_t *","FAR const posix_spawnattr_t *","FAR char *const []","FAR char *const []"
+"posix_spawn","spawn.h","!defined(CONFIG_BINFMT_EXEPATH)","int","FAR pid_t *","FAR const char *","FAR const posix_spawn_file_actions_t *","FAR const posix_spawnattr_t *","FAR char *const []","FAR char *const []"
 "pthread_barrier_destroy","pthread.h","!defined(CONFIG_DISABLE_PTHREAD)","int","FAR pthread_barrier_t*"
 "pthread_barrier_init","pthread.h","!defined(CONFIG_DISABLE_PTHREAD)","int","FAR pthread_barrier_t*","FAR const pthread_barrierattr_t*","unsigned int"
 "pthread_barrier_wait","pthread.h","!defined(CONFIG_DISABLE_PTHREAD)","int","FAR pthread_barrier_t*"