/usr/include/spinlock/clh.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.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 | /*
* 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_CLH_H
#define _CK_SPINLOCK_CLH_H
#include <ck_cc.h>
#include <ck_limits.h>
#include <ck_pr.h>
#include <stdbool.h>
#include <stddef.h>
#ifndef CK_F_SPINLOCK_CLH
#define CK_F_SPINLOCK_CLH
struct ck_spinlock_clh {
unsigned int wait;
struct ck_spinlock_clh *previous;
};
typedef struct ck_spinlock_clh ck_spinlock_clh_t;
CK_CC_INLINE static void
ck_spinlock_clh_init(struct ck_spinlock_clh **lock, struct ck_spinlock_clh *unowned)
{
ck_pr_store_ptr(&unowned->previous, NULL);
ck_pr_store_uint(&unowned->wait, false);
ck_pr_store_ptr(lock, unowned);
ck_pr_fence_store();
return;
}
CK_CC_INLINE static bool
ck_spinlock_clh_locked(struct ck_spinlock_clh **queue)
{
struct ck_spinlock_clh *head;
ck_pr_fence_load();
head = ck_pr_load_ptr(queue);
ck_pr_fence_load();
return ck_pr_load_uint(&head->wait);
}
CK_CC_INLINE static void
ck_spinlock_clh_lock(struct ck_spinlock_clh **queue, struct ck_spinlock_clh *thread)
{
struct ck_spinlock_clh *previous;
/* Indicate to the next thread on queue that they will have to block. */
thread->wait = true;
ck_pr_fence_store_atomic();
/* Mark current request as last request. Save reference to previous request. */
previous = ck_pr_fas_ptr(queue, thread);
thread->previous = previous;
/* Wait until previous thread is done with lock. */
ck_pr_fence_load();
while (ck_pr_load_uint(&previous->wait) == true)
ck_pr_stall();
ck_pr_fence_load();
return;
}
CK_CC_INLINE static void
ck_spinlock_clh_unlock(struct ck_spinlock_clh **thread)
{
struct ck_spinlock_clh *previous;
/*
* If there are waiters, they are spinning on the current node wait
* flag. The flag is cleared so that the successor may complete an
* acquisition. If the caller is pre-empted then the predecessor field
* may be updated by a successor's lock operation. In order to avoid
* this, save a copy of the predecessor before setting the flag.
*/
previous = thread[0]->previous;
/* We have to pay this cost anyways, use it as a compiler barrier too. */
ck_pr_fence_release();
ck_pr_store_uint(&(*thread)->wait, false);
/*
* Predecessor is guaranteed not to be spinning on previous request,
* so update caller to use previous structure. This allows successor
* all the time in the world to successfully read updated wait flag.
*/
*thread = previous;
return;
}
#endif /* CK_F_SPINLOCK_CLH */
#endif /* _CK_SPINLOCK_CLH_H */
|