42e7abd5db
This adds a dedicated counter updated with atomics when INVARIANTS is used. As a side effect one can reliably determine the lock is held for reading by at least one thread, but it's still not possible to find out whether curthread has the lock in said mode. This should be good enough in practice. Problem spotted by avg.
85 lines
2.6 KiB
C
85 lines
2.6 KiB
C
/*-
|
|
* SPDX-License-Identifier: BSD-3-Clause
|
|
*
|
|
* Copyright (c) 2007 Stephan Uphoff <ups@FreeBSD.org>
|
|
* 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.
|
|
* 3. Neither the name of the author nor the names of any co-contributors
|
|
* may be used to endorse or promote products derived from this software
|
|
* without specific prior written permission.
|
|
*
|
|
* 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.
|
|
*
|
|
* $FreeBSD$
|
|
*/
|
|
|
|
#ifndef _SYS__RMLOCK_H_
|
|
#define _SYS__RMLOCK_H_
|
|
|
|
/*
|
|
* Mostly reader/occasional writer lock.
|
|
*/
|
|
|
|
LIST_HEAD(rmpriolist,rm_priotracker);
|
|
|
|
struct rm_queue {
|
|
struct rm_queue *volatile rmq_next;
|
|
struct rm_queue *volatile rmq_prev;
|
|
};
|
|
|
|
struct rmlock {
|
|
struct lock_object lock_object;
|
|
volatile cpuset_t rm_writecpus;
|
|
LIST_HEAD(,rm_priotracker) rm_activeReaders;
|
|
union {
|
|
struct lock_object _rm_wlock_object;
|
|
struct mtx _rm_lock_mtx;
|
|
struct sx _rm_lock_sx;
|
|
} _rm_lock;
|
|
};
|
|
|
|
#define rm_wlock_object _rm_lock._rm_wlock_object
|
|
#define rm_lock_mtx _rm_lock._rm_lock_mtx
|
|
#define rm_lock_sx _rm_lock._rm_lock_sx
|
|
|
|
struct rm_priotracker {
|
|
struct rm_queue rmp_cpuQueue; /* Must be first */
|
|
struct rmlock *rmp_rmlock;
|
|
struct thread *rmp_thread;
|
|
int rmp_flags;
|
|
LIST_ENTRY(rm_priotracker) rmp_qentry;
|
|
};
|
|
|
|
#include <sys/_mutex.h>
|
|
|
|
struct rmslock_pcpu;
|
|
|
|
struct rmslock {
|
|
struct mtx mtx;
|
|
struct thread *owner;
|
|
struct rmslock_pcpu *pcpu;
|
|
int writers;
|
|
int readers;
|
|
int debug_readers;
|
|
};
|
|
|
|
#endif /* !_SYS__RMLOCK_H_ */
|