1 files changed, 130 insertions, 0 deletions
diff --git a/nuttx/sched/sched_unlock.c b/nuttx/sched/sched_unlock.c
new file mode 100644
index 000000000..9a52e8358
--- /dev/null
+++ b/nuttx/sched/sched_unlock.c
@@ -0,0 +1,130 @@
+/************************************************************************
+ * sched/sched_unlock.c
+ *
+ *   Copyright (C) 2007, 2009 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 <nuttx/arch.h>
+
+#include "os_internal.h"
+
+/************************************************************************
+ * Definitions
+ ************************************************************************/
+
+/************************************************************************
+ * Private Type Declarations
+ ************************************************************************/
+
+/************************************************************************
+ * Global Variables
+ ************************************************************************/
+
+/************************************************************************
+ * Private Variables
+ ************************************************************************/
+
+/************************************************************************
+ * Private Function Prototypes
+ ************************************************************************/
+
+/************************************************************************
+ * Private Functionss
+ ************************************************************************/
+
+/************************************************************************
+ * Public Functions
+ ************************************************************************/
+
+/************************************************************************
+ * Name:  sched_unlock
+ *
+ * Description:
+ *   This function decrements the preemption lock count.  Typically this
+ *   is paired with sched_lock() and concludes a critical section of
+ *   code.  Preemption will not be unlocked until sched_unlock() has
+ *   been called as many times as sched_lock().  When the lockcount is
+ *   decremented to zero, any tasks that were eligible to preempt the
+ *   current task will execute.
+ *
+ ************************************************************************/
+
+int sched_unlock(void)
+{
+  _TCB *rtcb = (_TCB*)g_readytorun.head;
+
+  /* Check for some special cases:  (1) rtcb may be NULL only during
+   * early boot-up phases, and (2) sched_unlock() should have no
+   * effect if called from the interrupt level.
+   */
+
+  if (rtcb && !up_interrupt_context())
+    {
+      /* Prevent context switches throughout the following */
+
+      irqstate_t flags = irqsave();
+
+      /* Decrement the preemption lock counter */
+
+      if (rtcb->lockcount)
+        {
+          rtcb->lockcount--;
+        }
+
+      /* Check if the lock counter has decremented to zero.  If so,
+       * then pre-emption has been re-enabled.
+       */
+
+      if (rtcb->lockcount <= 0)
+        {
+          rtcb->lockcount = 0;
+
+          /* Release any ready-to-run tasks that have collected in
+           * g_pendingtasks.
+           */
+
+         if (g_pendingtasks.head)
+           {
+             up_release_pending();
+           }
+        }
+
+      irqrestore(flags);
+    }
+  return OK;
+}