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Diffstat (limited to 'nuttx/sched/sched_unlock.c')
-rw-r--r-- | nuttx/sched/sched_unlock.c | 130 |
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; +} |