Correct an error in named application priority when SCHED_RR is enabled

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@4928 42af7a65-404d-4744-a932-0658087f49c3

2 files changed, 56 insertions, 17 deletions

diff --git a/apps/ChangeLog.txt b/apps/ChangeLog.txt
index 6aa705545..f2578c473 100755
--- a/apps/ChangeLog.txt
+++ b/apps/ChangeLog.txt
@@ -242,3 +242,9 @@
 	* apps/nshlib/nsh_fscmds.c:  Add the 'mv' command
 
 6.20 2012-xx-xx Gregory Nutt <gnutt@nuttx.org>
+
+	* namedapp/exec_namedapp.c - Correct an error when round robin scheduling
+	  is enabled.  The priority of the new, named application was erroneously
+	  being set to the priority of the parent thread; losing its configured
+	  priority.  Reported by Mike Smith.
+
diff --git a/apps/namedapp/exec_namedapp.c b/apps/namedapp/exec_namedapp.c
index 75e5b83d0..264fca7b9 100644
--- a/apps/namedapp/exec_namedapp.c
+++ b/apps/namedapp/exec_namedapp.c
@@ -122,33 +122,66 @@ int namedapp_isavail(FAR const char *appname)
  *   Execute the application with name 'appname', providing the arguments
  *   in the argv[] array.
  *
+ * Returned Value:
+ *   On success, the task ID of the named application is returned.  On
+ *   failure, -1 (ERROR) is returned an the errno value is set appropriately.
+ *
  ****************************************************************************/
 
 int exec_namedapp(FAR const char *appname, FAR const char **argv)
 {
-  int i;
-  
-  if ((i = namedapp_isavail(appname)) >= 0)
+  pid_t pid;
+  int index;
+
+  /* Verify that an application with this name exists */
+
+  index = namedapp_isavail(appname);
+  if (index >= 0)
     {
-#ifndef CONFIG_CUSTOM_STACK
-      i = task_create(namedapps[i].name, namedapps[i].priority, 
-                      namedapps[i].stacksize, namedapps[i].main, 
-                      (argv) ? &argv[1] : (const char **)NULL);
-#else
-      i = task_create(namedapps[i].name, namedapps[i].priority, namedapps[i].main,
-                      (argv) ? &argv[1] : (const char **)NULL);
-#endif
+      /* Disable pre-emption.  This means that although we start the named
+       * application here, it will not actually run until pre-emption is
+       * re-enabled below.
+       */
+
+      sched_lock();
+
+      /* Start the named application task */
+
+      pid = TASK_CREATE(namedapps[index].name, namedapps[index].priority, 
+                        namedapps[index].stacksize, namedapps[index].main, 
+                        (argv) ? &argv[1] : (const char **)NULL);
+
+      /* If robin robin scheduling is enabled, then set the scheduling policy
+       * of the new task to SCHED_RR before it has a chance to run.
+       */
 
 #if CONFIG_RR_INTERVAL > 0
-      if (i > 0)
+      if (pid > 0)
         {
           struct sched_param param;
-    
-          sched_getparam(0, &param);
-          sched_setscheduler(i, SCHED_RR, &param);
+
+          /* Pre-emption is disabled so the task creation and the
+           * following operation will be atomic.  The priority of the
+           * new task cannot yet have changed from its initial value.
+           */
+
+          param.sched_priority = namedapps[index].priority;
+          sched_setscheduler(pid, SCHED_RR, &param);
         }
 #endif
+      /* Now let the named application run */
+
+      sched_unlock();
+
+      /* Return the task ID of the new task if the task was sucessfully
+       * started.  Otherwise, pid will be ERROR (and the errno value will
+       * be set appropriately).
+       */
+
+      return pid;
     }
-  
-  return i;
+
+  /* Return ERROR with errno set appropriately */
+
+  return ERROR;
 }