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Diffstat (limited to 'include/spinlock/cas.h')
| -rw-r--r-- | include/spinlock/cas.h | 119 |
1 files changed, 119 insertions, 0 deletions
diff --git a/include/spinlock/cas.h b/include/spinlock/cas.h new file mode 100644 index 0000000..ff6d723 --- /dev/null +++ b/include/spinlock/cas.h @@ -0,0 +1,119 @@ +/* + * Copyright 2010-2015 Samy Al Bahra. + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#ifndef CK_SPINLOCK_CAS_H +#define CK_SPINLOCK_CAS_H + +#include <ck_backoff.h> +#include <ck_cc.h> +#include <ck_elide.h> +#include <ck_pr.h> +#include <ck_stdbool.h> + +#ifndef CK_F_SPINLOCK_CAS +#define CK_F_SPINLOCK_CAS +/* + * This is a simple CACAS (TATAS) spinlock implementation. + */ +struct ck_spinlock_cas { + unsigned int value; +}; +typedef struct ck_spinlock_cas ck_spinlock_cas_t; + +#define CK_SPINLOCK_CAS_INITIALIZER {false} + +CK_CC_INLINE static void +ck_spinlock_cas_init(struct ck_spinlock_cas *lock) +{ + + lock->value = false; + ck_pr_barrier(); + return; +} + +CK_CC_INLINE static bool +ck_spinlock_cas_trylock(struct ck_spinlock_cas *lock) +{ + unsigned int value; + + value = ck_pr_fas_uint(&lock->value, true); + ck_pr_fence_lock(); + return !value; +} + +CK_CC_INLINE static bool +ck_spinlock_cas_locked(struct ck_spinlock_cas *lock) +{ + bool r = ck_pr_load_uint(&lock->value); + + ck_pr_fence_acquire(); + return r; +} + +CK_CC_INLINE static void +ck_spinlock_cas_lock(struct ck_spinlock_cas *lock) +{ + + while (ck_pr_cas_uint(&lock->value, false, true) == false) { + while (ck_pr_load_uint(&lock->value) == true) + ck_pr_stall(); + } + + ck_pr_fence_lock(); + return; +} + +CK_CC_INLINE static void +ck_spinlock_cas_lock_eb(struct ck_spinlock_cas *lock) +{ + ck_backoff_t backoff = CK_BACKOFF_INITIALIZER; + + while (ck_pr_cas_uint(&lock->value, false, true) == false) + ck_backoff_eb(&backoff); + + ck_pr_fence_lock(); + return; +} + +CK_CC_INLINE static void +ck_spinlock_cas_unlock(struct ck_spinlock_cas *lock) +{ + + /* Set lock state to unlocked. */ + ck_pr_fence_unlock(); + ck_pr_store_uint(&lock->value, false); + return; +} + +CK_ELIDE_PROTOTYPE(ck_spinlock_cas, ck_spinlock_cas_t, + ck_spinlock_cas_locked, ck_spinlock_cas_lock, + ck_spinlock_cas_locked, ck_spinlock_cas_unlock) + +CK_ELIDE_TRYLOCK_PROTOTYPE(ck_spinlock_cas, ck_spinlock_cas_t, + ck_spinlock_cas_locked, ck_spinlock_cas_trylock) + +#endif /* CK_F_SPINLOCK_CAS */ +#endif /* CK_SPINLOCK_CAS_H */ |