133 lines
2.8 KiB
C
133 lines
2.8 KiB
C
/**
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* \file lock.h
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* License details are found in the file LICENSE.
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* \brief
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* Declare functions implementing spin lock.
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* \author Taku Shimosawa <shimosawa@is.s.u-tokyo.ac.jp> \par
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* Copyright (C) 2011 - 2012 Taku Shimosawa
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*/
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/*
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* HISTORY
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*/
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#ifndef __HEADER_GENERIC_IHK_LOCK
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#define __HEADER_GENERIC_IHK_LOCK
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#include <arch-lock.h>
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#ifndef ARCH_MCS_LOCK
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/* An architecture independent implementation of the
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* Mellor-Crummey Scott (MCS) lock */
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typedef struct mcs_lock_node {
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#ifndef SPIN_LOCK_IN_MCS
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unsigned long locked;
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struct mcs_lock_node *next;
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#endif
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unsigned long irqsave;
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#ifdef SPIN_LOCK_IN_MCS
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ihk_spinlock_t spinlock;
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#endif
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#ifndef ENABLE_UBSAN
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} __aligned(64) mcs_lock_node_t;
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#else
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} mcs_lock_node_t;
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#endif
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typedef mcs_lock_node_t mcs_lock_t;
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static void mcs_lock_init(struct mcs_lock_node *node)
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{
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#ifdef SPIN_LOCK_IN_MCS
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ihk_mc_spinlock_init(&node->spinlock);
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#else
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node->locked = 0;
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node->next = NULL;
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#endif // SPIN_LOCK_IN_MCS
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}
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static void __mcs_lock_lock(struct mcs_lock_node *lock,
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struct mcs_lock_node *node)
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{
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#ifdef SPIN_LOCK_IN_MCS
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ihk_mc_spinlock_lock_noirq(&lock->spinlock);
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#else
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struct mcs_lock_node *pred;
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node->next = NULL;
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node->locked = 0;
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__atomic_exchange(&(lock->next), &node, &pred, __ATOMIC_SEQ_CST);
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if (pred) {
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node->locked = 1;
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pred->next = node;
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while (node->locked != 0) {
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cpu_pause();
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}
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}
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#endif // SPIN_LOCK_IN_MCS
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}
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static void __mcs_lock_unlock(struct mcs_lock_node *lock,
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struct mcs_lock_node *node)
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{
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#ifdef SPIN_LOCK_IN_MCS
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ihk_mc_spinlock_unlock_noirq(&lock->spinlock);
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#else
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if (node->next == NULL) {
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struct mcs_lock_node *desired = NULL;
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struct mcs_lock_node *expected = node;
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if (__atomic_compare_exchange(&(lock->next), &expected, &desired, 0,
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__ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST)) {
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return;
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}
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while (node->next == NULL) {
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cpu_pause();
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}
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}
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node->next->locked = 0;
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#endif // SPIN_LOCK_IN_MCS
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}
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static void mcs_lock_lock_noirq(struct mcs_lock_node *lock,
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struct mcs_lock_node *node)
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{
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preempt_disable();
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__mcs_lock_lock(lock, node);
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}
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static void mcs_lock_unlock_noirq(struct mcs_lock_node *lock,
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struct mcs_lock_node *node)
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{
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__mcs_lock_unlock(lock, node);
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preempt_enable();
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}
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static void mcs_lock_lock(struct mcs_lock_node *lock,
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struct mcs_lock_node *node)
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{
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node->irqsave = cpu_disable_interrupt_save();
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mcs_lock_lock_noirq(lock, node);
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}
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static void mcs_lock_unlock(struct mcs_lock_node *lock,
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struct mcs_lock_node *node)
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{
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mcs_lock_unlock_noirq(lock, node);
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cpu_restore_interrupt(node->irqsave);
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}
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#endif // ARCH_MCS_LOCK
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#ifndef IHK_STATIC_SPINLOCK_FUNCS
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void ihk_mc_spinlock_init(ihk_spinlock_t *);
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void ihk_mc_spinlock_lock(ihk_spinlock_t *, unsigned long *);
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void ihk_mc_spinlock_unlock(ihk_spinlock_t *, unsigned long *);
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#endif
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#endif
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