Add CONFIG_SPINLOCK. Also need spinunlock() and spinlock_initialize()
This commit is contained in:
Gregory Nutt
parent
b022f1e9d8
commit
2c0ad2564f
@ -41,7 +41,9 @@
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sched.h>
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#include <stdint.h>
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#ifdef CONFIG_SPINLOCK
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/* The architecture specific spinlock.h header file must also provide the
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* following:
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@ -55,6 +57,18 @@
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#include <arch/spinlock.h>
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/****************************************************************************
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* Public Types
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****************************************************************************/
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struct spinlock_s
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{
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spinlock_t sp_lock; /* Indicates if the spinlock is locked or not. See the
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* values SP_LOCKED and SP_UNLOCKED. */
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uint8_t sp_cpu; /* CPU holding the lock */
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uint16_t sp_count; /* The count of references by this CPU on the lock */
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};
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/****************************************************************************
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* Public Function Prototypes
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****************************************************************************/
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@ -82,21 +96,60 @@
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spinlock_t up_testset(FAR spinlock_t *lock);
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/****************************************************************************
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* Name: spinlock
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* Name: spinlock_initialize
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*
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* Description:
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* Loop until the spinlock is successfully locked.
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* Initialize a spinlock object to its initial, unlocked state.
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*
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* Input Parameters:
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* lock - The address of spinlock object.
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* lock - A reference to the spinlock object to be initialized.
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*
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* Returned Value:
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* None. When the function returned, the spinlocked was successfully
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* locked by this CPU.
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* None.
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*
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****************************************************************************/
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#define spinlock(l) while (up_testset(l) == SP_LOCKED) (void)sched_yield()
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void spinlock_initialize(FAR struct spinlock_s *lock);
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#endif /* CONFIG_SIG_EVTHREAD && CONFIG_BUILD_FLAT */
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/****************************************************************************
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* Name: spinlock
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*
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* Description:
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* If this CPU does not already hold the spinlock, then loop until the
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* spinlock is successfully locked.
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*
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* Input Parameters:
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* lock - A reference to the spinlock object to lock.
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*
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* Returned Value:
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* None. When the function returns, the spinlock was successfully locked
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* by this CPU.
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*
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* Assumptions:
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* Not running at the interrupt level.
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*
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****************************************************************************/
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void spinlock(FAR struct spinlock_s *lock);
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/****************************************************************************
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* Name: spinunlock
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*
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* Description:
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* Release one count on a spinlock.
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*
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* Input Parameters:
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* lock - A reference to the spinlock object to unlock.
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*
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* Returned Value:
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* None.
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*
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* Assumptions:
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* Not running at the interrupt level.
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*
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****************************************************************************/
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void spinunlock(FAR struct spinlock_s *lock);
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#endif /* CONFIG_SPINLOCK */
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#endif /* __INCLUDE_NUTTX_SPINLOCK_H */
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@ -307,6 +307,11 @@ config RR_INTERVAL
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Round roben scheduling (SCHED_RR) is enabled by setting this
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interval to a positive, non-zero value.
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config SPINLOCK
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bool "Support Spinlocks"
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default n
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depends on EXPERIMENTAL
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config SCHED_SPORADIC
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bool "Support sporadic scheduling"
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default n
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@ -41,6 +41,10 @@ ifeq ($(CONFIG_PRIORITY_INHERITANCE),y)
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CSRCS += sem_initialize.c sem_holder.c
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endif
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ifeq ($(CONFIG_SPINLOCK),y)
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CSRCS += spinlock.c
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endif
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# Include semaphore build support
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DEPPATH += --dep-path semaphore
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227
sched/semaphore/spinlock.c
Normal file
227
sched/semaphore/spinlock.c
Normal file
@ -0,0 +1,227 @@
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/****************************************************************************
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* sched/semaphore/spinlock.c
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*
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* Copyright (C) 2016 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/spinlock.h>
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#include "sched/sched.h"
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#ifdef CONFIG_SPINLOCK
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#define IMPOSSIBLE_CPU 0xff
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/* REVISIT: What happens if a thread taks a spinlock while running on one
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* CPU, but is suspended, then reassigned to another CPU where it runs and
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* eventually calls spinunlock(). One solution might be to lock a thread to
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* a CPU if it holds a spinlock. That would assure that it never runs on
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* any other CPU and avoids such complexities.
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*/
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#undef CONFIG_SPINLOCK_LOCKDOWN /* Feature not yet available */
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: spinlock_initialize
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*
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* Description:
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* Initialize a spinlock object to its initial, unlocked state.
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*
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* Input Parameters:
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* lock - A reference to the spinlock object to be initialized.
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*
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* Returned Value:
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* None.
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*
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****************************************************************************/
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void spinlock_initialize(FAR struct spinlock_s *lock)
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{
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DEBUGASSERT(lock != NULL);
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lock->sp_lock = SP_UNLOCKED;
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lock->sp_cpu = IMPOSSIBLE_CPU;
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lock->sp_count = 0;
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}
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/****************************************************************************
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* Name: spinlock
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*
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* Description:
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* If this CPU does not already hold the spinlock, then loop until the
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* spinlock is successfully locked.
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*
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* Input Parameters:
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* lock - A reference to the spinlock object to lock.
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*
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* Returned Value:
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* None. When the function returns, the spinlock was successfully locked
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* by this CPU.
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*
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* Assumptions:
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* Not running at the interrupt level.
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*
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****************************************************************************/
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void spinlock(FAR struct spinlock_s *lock)
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{
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irqstate_t flags;
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uint8_t cpu = this_cpu();
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/* Disable interrupts (all CPUs) */
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flags = irqsave();
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/* Do we already hold the lock on this CPU? */
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if (lock->sp_cpu == cpu)
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{
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/* Yes... just increment the number of references we have on the lock */
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lock->sp_count++;
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DEBUGASSERT(lock->sp_lock = SP_LOCKED && lock->sp_count > 0);
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}
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else
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{
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#ifdef CONFIG_SPINLOCK_LOCKDOWN
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/* REVISIT: What happens if this thread is suspended, then reassigned
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* to another CPU where it runs and eventually calls spinunlock().
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* One solution might be to lock a thread to a CPU if it holds a
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* spinlock. That would assure that it never runs on any other CPU
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* and avoids such complexities.
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*/
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# warning Missing logic
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#endif
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/* Take the lock */
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while (up_testset(&lock->sp_lock) == SP_LOCKED)
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{
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irqrestore(flags);
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sched_yield();
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flags = irqsave();
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}
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/* Take one count on the lock */
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lock->sp_cpu = cpu;
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lock->sp_count = 1;
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}
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irqrestore(flags);
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}
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/****************************************************************************
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* Name: spinunlock
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*
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* Description:
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* Release one count on a spinlock.
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*
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* Input Parameters:
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* lock - A reference to the spinlock object to unlock.
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*
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* Returned Value:
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* None.
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*
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* Assumptions:
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* Not running at the interrupt level.
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*
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****************************************************************************/
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void spinunlock(FAR struct spinlock_s *lock)
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{
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irqstate_t flags;
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#ifdef CONFIG_SPINLOCK_LOCKDOWN
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uint8_t cpu = this_cpu();
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#endif
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/* Disable interrupts (all CPUs) */
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flags = irqsave();
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#ifdef CONFIG_SPINLOCK_LOCKDOWN
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/* REVISIT: What happens if this thread took the lock on a different CPU,
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* was suspended, then reassigned to this CPU where it runs and eventually
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* calls spinunlock(). One solution might be to lock a thread to a CPU if
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* it holds a spinlock. That would assure that it never runs on any other
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* CPU and avoids such complexities.
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*/
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DEBUGASSERT(lock != NULL && lock->sp-lock = SP_LOCKED &&
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lock->sp_cpu == this_cpu() && lock->sp_count > 0);
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/* Do we already hold the lock? */
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if (lock->sp_cpu == cpu)
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#else
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DEBUGASSERT(lock != NULL && lock->sp-lock = SP_LOCKED &&
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lock->sp_count > 0);
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#endif
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{
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/* Yes... just decrement the number of references we have on the lock */
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if (lock->sp_count <= 1)
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{
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/* The count must decremented to zero */
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lock->sp_count = 0;
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lock->sp_cpu = IMPOSSIBLE_CPU;
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lock->sp_lock = SP_UNLOCKED;
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}
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else
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{
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lock->sp_count--;
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}
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}
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irqrestore(flags);
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}
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#endif /* CONFIG_SPINLOCK */
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