SMP: Forgot to add a file before the last commit
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Gregory Nutt
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/****************************************************************************
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* sched/irq/irq_csection.c
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*
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* Copyright (C) 2007-2008, 2010 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/spinlock.h>
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#include <arch/irq.h>
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#include "sched/sched.h"
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#include "irq/irq.h"
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#ifdef CONFIG_SMP
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/****************************************************************************
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* Public Data
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****************************************************************************/
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/* This is the spinlock that enforces critical sections when interrupts are
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* disabled.
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*/
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spinlock_t g_cpu_irqlock = SP_UNLOCKED;
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: enter_critical_section
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*
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* Description:
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* Take the CPU IRQ lock and disable interrupts on all CPUs. A thread-
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* specific counter is increment to indicate that the thread has IRQs
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* disabled and to support nested calls to enter_critical_section().
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*
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****************************************************************************/
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irqstate_t enter_critical_section(void)
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{
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FAR struct tcb_s *rtcb = this_task();
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/* Do we already have interrupts disabled? */
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if (rtcb->irqcount > 0)
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{
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/* Yes... make sure that the spinlock is set and increment the IRQ
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* lock count.
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*/
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DEBUGASSERT(g_cpu_irqlock == SP_LOCKED && rtcb->irqcount < INT16_MAX);
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rtcb->irqcount++;
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}
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else
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{
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/* NO.. Take the spinlock to get exclusive access and set the lock
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* count to 1.
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*/
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spin_lock(&g_cpu_irqlock);
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rtcb->irqcount = 1;
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}
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/* Then disable interrupts (if they have not already been disabeld) */
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return irqsave();
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}
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/****************************************************************************
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* Name: leave_critical_section
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*
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* Description:
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* Decrement the IRQ lock count and if it decrements to zero then release
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* the spinlock.
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*
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****************************************************************************/
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void leave_critical_section(irqstate_t flags)
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{
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FAR struct tcb_s *rtcb = this_task();
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DEBUGASSERT(rtcb->irqcount > 0);
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/* Will we still have interrupts disabled after decrementing the count? */
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if (rtcb->irqcount > 1)
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{
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/* Yes... make sure that the spinlock is set */
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DEBUGASSERT(g_cpu_irqlock == SP_LOCKED);
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rtcb->irqcount--;
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}
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else
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{
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/* NO.. Take the spinlock to get exclusive access. */
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rtcb->irqcount = 0;
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spin_unlock(g_cpu_irqlock);
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}
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/* Restore the previous interrupt state which may still be interrupts
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* disabled (but we don't have a mechanism to verify that now)
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*/
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irqrestore(flags);
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}
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#endif /* CONFIG_SMP */
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