Repartition functionality in preparation for nested, pending reprioritization

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@1591 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 128 insertions, 0 deletions

diff --git a/nuttx/sched/sched_reprioritize.c b/nuttx/sched/sched_reprioritize.c
new file mode 100644
index 000000000..c9e165104
--- /dev/null
+++ b/nuttx/sched/sched_reprioritize.c
@@ -0,0 +1,128 @@
+/****************************************************************************
+ * sched/sched_reprioritize.c
+ *
+ *   Copyright (C) 2009 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * 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 <sys/types.h>
+#include <sched.h>
+#include <errno.h>
+
+#include "os_internal.h"
+
+#ifdef CONFIG_PRIORITY_INHERITANCE
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name:  sched_reprioritize
+ *
+ * Description:
+ *   This function sets the priority of a specified task.
+ *
+ *   NOTE: Setting a task's priority to the same value has a similar
+ *   effect to sched_yield() -- The task will be moved to  after all other
+ *   tasks with the same priority.
+ *
+ * Inputs:
+ *   tcb - the TCB of task to reprioritize.
+ *   sched_priority - The new task priority
+ *
+ * Return Value:
+ *   On success, sched_setparam() returns 0 (OK). On error, -1
+ *  (ERROR) is returned, and errno is set appropriately.
+ *
+ *  EINVAL The parameter 'param' is invalid or does not make
+ *         sense for the current scheduling policy.
+ *  EPERM  The calling task does not have appropriate privileges.
+ *  ESRCH  The task whose ID is pid could not be found.
+ *
+ * Assumptions:
+ *
+ ****************************************************************************/
+
+int sched_reprioritize(FAR _TCB *tcb, int sched_priority)
+{
+  /* This function is equivalent to sched_setpriority() BUT it also has the
+   * side effect of discarding all priority inheritance history.  This is
+   * done only on explicit, user-initiated reprioritization.
+   */
+
+  int ret = sched_setpriority(tcb, sched_priority);
+  if (ret == 0)
+    {
+       /* Reset the base_priority -- the priority that the thread would return
+        * to once it posts the semaphore.
+        */
+
+       tcb->base_priority  = (ubyte)sched_priority;
+
+       /* Discard any pending reprioritizations as well */
+
+#  if CONFIG_SEM_NNESTPRIO > 0
+       tcb->npend_reprio   = 0;
+#  endif
+    }
+  return ret;
+}
+#endif /* CONFIG_PRIORITY_INHERITANCE */