Resync new repository with old repo r5166

git-svn-id: http://svn.code.sf.net/p/nuttx/code/trunk@5153 42af7a65-404d-4744-a932-0658087f49c3
2026-11-04 20:01:36 +08:00 · 2012-09-17 18:18:44 +00:00
commit 57623d42eb
5691 changed files with 1361853 additions and 0 deletions
@@ -0,0 +1,182 @@
+/****************************************************************************
+ * sched/sem_post.c
+ *
+ *   Copyright (C) 2007-2009, 2012 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 <limits.h>
+#include <semaphore.h>
+#include <sched.h>
+#include <nuttx/arch.h>
+
+#include "os_internal.h"
+#include "sem_internal.h"
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: sem_post
+ *
+ * Description:
+ *   When a task has finished with a semaphore, it will call sem_post().
+ *   This function unlocks the semaphore referenced by sem by performing the
+ *   semaphore unlock operation on that semaphore.
+ *
+ *   If the semaphore value resulting from this operation is positive, then
+ *   no tasks were blocked waiting for the semaphore to become unlocked; the
+ *   semaphore is simply incremented.
+ *
+ *   If the value of the semaphore resulting from this operation is zero,
+ *   then one of the tasks blocked waiting for the semaphore shall be
+ *   allowed to return successfully from its call to sem_wait().
+ *
+ * Parameters:
+ *   sem - Semaphore descriptor
+ *
+ * Return Value:
+ *   0 (OK) or -1 (ERROR) if unsuccessful
+ *
+ * Assumptions:
+ *   This function cannot be called from an interrupt handler.
+ *   It assumes the currently executing task is the one that
+ *   is performing the unlock.
+ *
+ ****************************************************************************/
+
+int sem_post(FAR sem_t *sem)
+{
+  FAR _TCB  *stcb = NULL;
+  int        ret = ERROR;
+  irqstate_t saved_state;
+
+  /* Make sure we were supplied with a valid semaphore. */
+
+  if (sem)
+    {
+      /* The following operations must be performed with interrupts
+       * disabled because sem_post() may be called from an interrupt
+       * handler.
+       */
+
+      saved_state = irqsave();
+
+      /* Perform the semaphore unlock operation. */
+
+      ASSERT(sem->semcount < SEM_VALUE_MAX);
+      sem_releaseholder(sem);
+      sem->semcount++;
+
+#ifdef CONFIG_PRIORITY_INHERITANCE
+      /* Don't let any unblocked tasks run until we complete any priority
+       * restoration steps.  Interrupts are disabled, but we do not want
+       * the head of the read-to-run list to be modified yet.
+       *
+       * NOTE: If this sched_lock is called from an interrupt handler, it
+       * will do nothing.
+       */
+
+      sched_lock();
+#endif
+      /* If the result of of semaphore unlock is non-positive, then
+       * there must be some task waiting for the semaphore.
+       */
+
+      if (sem->semcount <= 0)
+        {
+          /* Check if there are any tasks in the waiting for semaphore
+           * task list that are waiting for this semaphore. This is a
+           * prioritized list so the first one we encounter is the one
+           * that we want.
+           */
+
+          for (stcb = (FAR _TCB*)g_waitingforsemaphore.head;
+               (stcb && stcb->waitsem != sem);
+               stcb = stcb->flink);
+
+          if (stcb)
+            {
+              /* It is, let the task take the semaphore */
+
+              stcb->waitsem = NULL;
+
+              /* Restart the waiting task. */
+
+              up_unblock_task(stcb);
+            }
+        }
+
+      /* Check if we need to drop the priority of any threads holding
+       * this semaphore.  The priority could have been boosted while they
+       * held the semaphore.
+       */
+
+#ifdef CONFIG_PRIORITY_INHERITANCE
+      sem_restorebaseprio(stcb, sem);
+      sched_unlock();
+#endif
+      ret = OK;
+
+      /* Interrupts may now be enabled. */
+
+      irqrestore(saved_state);
+    }
+
+  return ret;
+}