forked from Archive/PX4-Autopilot
111 lines
4.2 KiB
C
111 lines
4.2 KiB
C
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/************************************************************************
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* sched/sched_lock.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 <sched.h>
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#include <assert.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_lock
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*
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* Description:
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* This function disables context switching by disabling addition of
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* new tasks to the g_readytorun task list. The task that calls this
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* function will be the only task that is allowed to run until it
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* either calls sched_unlock() (the appropriate number of times) or
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* until it blocks itself.
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*
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* Inputs
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* None
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*
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* Return Value:
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* OK on success; ERROR on failure
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*
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************************************************************************/
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int sched_lock(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_lock() 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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ASSERT(rtcb->lockcount < MAX_LOCK_COUNT);
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rtcb->lockcount++;
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}
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return OK;
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}
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