/*
* Copyright (c) 2012-2017 Richard Braun.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see .
*
*
* Spin locks.
*
* Critical sections built with spin locks run with preemption disabled.
*
* This module provides fair spin locks which guarantee time-bounded lock
* acquisition depending only on the number of contending processors.
*/
#ifndef _KERN_SPINLOCK_H
#define _KERN_SPINLOCK_H
#include
#include
#include
#include
#include
struct spinlock;
#define spinlock_assert_locked(lock) assert((lock)->value != SPINLOCK_UNLOCKED)
#ifdef SPINLOCK_TRACK_OWNER
static inline void
spinlock_transfer_owner(struct spinlock *lock, struct thread *owner)
{
assert(lock->owner == thread_self());
lock->owner = owner;
}
#else /* SPINLOCK_TRACK_OWNER */
#define spinlock_transfer_owner(lock, owner)
#endif /* SPINLOCK_TRACK_OWNER */
/*
* Initialize a spin lock.
*/
void spinlock_init(struct spinlock *lock);
/*
* Attempt to lock the given spin lock.
*
* Return 0 on success, ERROR_BUSY if the spin lock is already locked.
*
* Preemption is disabled on success.
*/
static inline int
spinlock_trylock(struct spinlock *lock)
{
int error;
thread_preempt_disable();
error = spinlock_lock_fast(lock);
if (unlikely(error)) {
thread_preempt_enable();
}
return error;
}
/*
* Lock a spin lock.
*
* If the spin lock is already locked, the calling thread spins until the
* spin lock is unlocked.
*
* A spin lock can only be locked once.
*
* This function disables preemption.
*/
static inline void
spinlock_lock(struct spinlock *lock)
{
thread_preempt_disable();
spinlock_lock_common(lock);
}
/*
* Unlock a spin lock.
*
* The spin lock must be locked, and must have been locked on the same
* processor it is unlocked on.
*
* This function may reenable preemption.
*/
static inline void
spinlock_unlock(struct spinlock *lock)
{
spinlock_unlock_common(lock);
thread_preempt_enable();
}
/*
* Versions of the spinlock functions that also disable interrupts during
* critical sections.
*/
/*
* Attempt to lock the given spin lock.
*
* Return 0 on success, ERROR_BUSY if the spin lock is already locked.
*
* Preemption and interrupts are disabled on success, in which case the
* flags passed by the caller are filled with the previous value of the
* CPU flags.
*/
static inline int
spinlock_trylock_intr_save(struct spinlock *lock, unsigned long *flags)
{
int error;
thread_preempt_disable_intr_save(flags);
error = spinlock_lock_fast(lock);
if (unlikely(error)) {
thread_preempt_enable_intr_restore(*flags);
}
return error;
}
/*
* Lock a spin lock.
*
* If the spin lock is already locked, the calling thread spins until the
* spin lock is unlocked.
*
* A spin lock can only be locked once.
*
* This function disables preemption and interrupts. The flags passed by
* the caller are filled with the previous value of the CPU flags.
*/
static inline void
spinlock_lock_intr_save(struct spinlock *lock, unsigned long *flags)
{
thread_preempt_disable_intr_save(flags);
spinlock_lock_common(lock);
}
/*
* Unlock a spin lock.
*
* The spin lock must be locked, and must have been locked on the same
* processor it is unlocked on.
*
* This function may reenable preemption and interrupts, using the given
* flags which must have been obtained with a lock or trylock operation.
*/
static inline void
spinlock_unlock_intr_restore(struct spinlock *lock, unsigned long flags)
{
spinlock_unlock_common(lock);
thread_preempt_enable_intr_restore(flags);
}
/*
* This init operation provides :
* - uncontended spinlock locking
*
* Contended locking may only occur after starting APs.
*/
INIT_OP_DECLARE(spinlock_setup);
#endif /* _KERN_SPINLOCK_H */