You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
134 lines
3.9 KiB
134 lines
3.9 KiB
/*
|
|
* Copyright 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_TFLOCK_TICKET_H
|
|
#define _CK_TFLOCK_TICKET_H
|
|
|
|
/*
|
|
* This is an implementation of task-fair locks derived from the work
|
|
* described in:
|
|
* John M. Mellor-Crummey and Michael L. Scott. 1991.
|
|
* Scalable reader-writer synchronization for shared-memory
|
|
* multiprocessors. SIGPLAN Not. 26, 7 (April 1991), 106-113.
|
|
*/
|
|
|
|
#include <ck_cc.h>
|
|
#include <ck_pr.h>
|
|
|
|
struct ck_tflock_ticket {
|
|
uint32_t request;
|
|
uint32_t completion;
|
|
};
|
|
typedef struct ck_tflock_ticket ck_tflock_ticket_t;
|
|
|
|
#define CK_TFLOCK_TICKET_INITIALIZER { 0, 0 }
|
|
|
|
#define CK_TFLOCK_TICKET_RC_INCR 0x10000U /* Read-side increment. */
|
|
#define CK_TFLOCK_TICKET_WC_INCR 0x1U /* Write-side increment. */
|
|
#define CK_TFLOCK_TICKET_W_MASK 0xffffU /* Write-side mask. */
|
|
#define CK_TFLOCK_TICKET_WC_TOPMSK 0x8000U /* Write clear mask for overflow. */
|
|
#define CK_TFLOCK_TICKET_RC_TOPMSK 0x80000000U /* Read clear mask for overflow. */
|
|
|
|
CK_CC_INLINE static uint32_t
|
|
ck_tflock_ticket_fca_32(uint32_t *target, uint32_t mask, uint32_t delta)
|
|
{
|
|
uint32_t snapshot = ck_pr_load_32(target);
|
|
uint32_t goal;
|
|
|
|
for (;;) {
|
|
goal = (snapshot & ~mask) + delta;
|
|
if (ck_pr_cas_32_value(target, snapshot, goal, &snapshot) == true)
|
|
break;
|
|
|
|
ck_pr_stall();
|
|
}
|
|
|
|
return snapshot;
|
|
}
|
|
|
|
CK_CC_INLINE static void
|
|
ck_tflock_ticket_init(struct ck_tflock_ticket *pf)
|
|
{
|
|
|
|
pf->request = pf->completion = 0;
|
|
return;
|
|
}
|
|
|
|
CK_CC_INLINE static void
|
|
ck_tflock_ticket_write_lock(struct ck_tflock_ticket *lock)
|
|
{
|
|
uint32_t previous;
|
|
|
|
previous = ck_tflock_ticket_fca_32(&lock->request, CK_TFLOCK_TICKET_WC_TOPMSK,
|
|
CK_TFLOCK_TICKET_WC_INCR);
|
|
ck_pr_fence_atomic_load();
|
|
while (ck_pr_load_32(&lock->completion) != previous)
|
|
ck_pr_stall();
|
|
|
|
ck_pr_fence_acquire();
|
|
return;
|
|
}
|
|
|
|
CK_CC_INLINE static void
|
|
ck_tflock_ticket_write_unlock(struct ck_tflock_ticket *lock)
|
|
{
|
|
|
|
ck_pr_fence_release();
|
|
ck_tflock_ticket_fca_32(&lock->completion, CK_TFLOCK_TICKET_WC_TOPMSK,
|
|
CK_TFLOCK_TICKET_WC_INCR);
|
|
return;
|
|
}
|
|
|
|
CK_CC_INLINE static void
|
|
ck_tflock_ticket_read_lock(struct ck_tflock_ticket *lock)
|
|
{
|
|
uint32_t previous;
|
|
|
|
previous = ck_tflock_ticket_fca_32(&lock->request, CK_TFLOCK_TICKET_RC_TOPMSK,
|
|
CK_TFLOCK_TICKET_RC_INCR) & CK_TFLOCK_TICKET_W_MASK;
|
|
|
|
ck_pr_fence_atomic_load();
|
|
|
|
while ((ck_pr_load_uint(&lock->completion) & CK_TFLOCK_TICKET_W_MASK) != previous)
|
|
ck_pr_stall();
|
|
|
|
ck_pr_fence_acquire();
|
|
return;
|
|
}
|
|
|
|
CK_CC_INLINE static void
|
|
ck_tflock_ticket_read_unlock(struct ck_tflock_ticket *lock)
|
|
{
|
|
|
|
ck_pr_fence_release();
|
|
ck_tflock_ticket_fca_32(&lock->completion, CK_TFLOCK_TICKET_RC_TOPMSK,
|
|
CK_TFLOCK_TICKET_RC_INCR);
|
|
return;
|
|
}
|
|
|
|
#endif /* _CK_TFLOCK_TICKET_H */
|
|
|