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131 lines
4.7 KiB
131 lines
4.7 KiB
/************************************************************************ |
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* sched/sched_unlock.c |
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* |
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* Copyright (C) 2007, 2009 Gregory Nutt. All rights reserved. |
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* Author: Gregory Nutt <gnutt@nuttx.org> |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in |
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* the documentation and/or other materials provided with the |
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* distribution. |
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* 3. Neither the name NuttX nor the names of its contributors may be |
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* used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS |
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE |
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, |
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, |
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS |
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED |
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN |
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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* POSSIBILITY OF SUCH DAMAGE. |
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* |
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************************************************************************/ |
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/************************************************************************ |
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* Included Files |
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************************************************************************/ |
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#include <nuttx/config.h> |
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#include <nuttx/arch.h> |
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#include "os_internal.h" |
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/************************************************************************ |
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* Definitions |
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************************************************************************/ |
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/************************************************************************ |
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* Private Type Declarations |
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************************************************************************/ |
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/************************************************************************ |
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* Global Variables |
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************************************************************************/ |
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/************************************************************************ |
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* Private Variables |
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************************************************************************/ |
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/************************************************************************ |
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* Private Function Prototypes |
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************************************************************************/ |
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/************************************************************************ |
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* Private Functionss |
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************************************************************************/ |
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/************************************************************************ |
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* Public Functions |
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************************************************************************/ |
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/************************************************************************ |
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* Name: sched_unlock |
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* |
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* Description: |
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* This function decrements the preemption lock count. Typically this |
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* is paired with sched_lock() and concludes a critical section of |
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* code. Preemption will not be unlocked until sched_unlock() has |
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* been called as many times as sched_lock(). When the lockcount is |
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* decremented to zero, any tasks that were eligible to preempt the |
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* current task will execute. |
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* |
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************************************************************************/ |
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int sched_unlock(void) |
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{ |
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_TCB *rtcb = (_TCB*)g_readytorun.head; |
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/* Check for some special cases: (1) rtcb may be NULL only during |
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* early boot-up phases, and (2) sched_unlock() should have no |
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* effect if called from the interrupt level. |
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*/ |
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if (rtcb && !up_interrupt_context()) |
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{ |
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/* Prevent context switches throughout the following */ |
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irqstate_t flags = irqsave(); |
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/* Decrement the preemption lock counter */ |
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if (rtcb->lockcount) |
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{ |
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rtcb->lockcount--; |
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} |
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/* Check if the lock counter has decremented to zero. If so, |
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* then pre-emption has been re-enabled. |
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*/ |
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if (rtcb->lockcount <= 0) |
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{ |
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rtcb->lockcount = 0; |
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/* Release any ready-to-run tasks that have collected in |
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* g_pendingtasks. |
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*/ |
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if (g_pendingtasks.head) |
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{ |
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up_release_pending(); |
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} |
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} |
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irqrestore(flags); |
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} |
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return OK; |
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}
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