/usr/include/spinlock/cas.h is in libck-dev 0.3.5-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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* Copyright 2010-2014 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 <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)
{
ck_pr_store_uint(&lock->value, false);
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);
if (value == false)
ck_pr_fence_acquire();
return !value;
}
CK_CC_INLINE static bool
ck_spinlock_cas_locked(struct ck_spinlock_cas *lock)
{
ck_pr_fence_load();
return ck_pr_load_uint(&lock->value);
}
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_acquire();
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_acquire();
return;
}
CK_CC_INLINE static void
ck_spinlock_cas_unlock(struct ck_spinlock_cas *lock)
{
/* Set lock state to unlocked. */
ck_pr_fence_release();
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 */
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