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/* $NetBSD: psref.h,v 1.4 2019/05/17 03:34:27 ozaki-r Exp $ */
/*-
* Copyright (c) 2016 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Taylor R. Campbell.
*
* 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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 _SYS_PSREF_H
#define _SYS_PSREF_H
#ifdef _KERNEL_OPT
#include "opt_psref_debug.h"
#endif
#include <sys/types.h>
#include <sys/queue.h>
struct cpu_info;
struct lwp;
struct psref;
struct psref_class;
struct psref_target;
/*
* struct psref_target
*
* Bookkeeping for an object to which users can acquire passive
* references. This is compact so that it can easily be embedded
* into many multitudes of objects, e.g. IP packet flows.
*
* prt_draining is false on initialization, and may be written
* only once, to make it true, when someone has prevented new
* references from being created and wants to drain the target in
* order to destroy it.
*/
struct psref_target {
struct psref_class *prt_class;
bool prt_draining;
};
/*
* struct psref
*
* Bookkeeping for a single passive reference. There should only
* be a few of these per CPU in the system at once, no matter how
* many targets are stored, so these are a bit larger than struct
* psref_target. The contents of struct psref may be read and
* written only on the local CPU.
*/
struct psref {
SLIST_ENTRY(psref) psref_entry;
void *psref_debug; /* For debugging */
const struct psref_target *psref_target;
struct lwp *psref_lwp;
struct cpu_info *psref_cpu;
};
#ifdef _KERNEL
void psref_init(void);
struct psref_class *
psref_class_create(const char *, int);
void psref_class_destroy(struct psref_class *);
void psref_target_init(struct psref_target *, struct psref_class *);
void psref_target_destroy(struct psref_target *, struct psref_class *);
void psref_acquire(struct psref *, const struct psref_target *,
struct psref_class *);
void psref_release(struct psref *, const struct psref_target *,
struct psref_class *);
void psref_copy(struct psref *, const struct psref *,
struct psref_class *);
/* For use only in assertions. */
bool psref_held(const struct psref_target *, struct psref_class *);
#ifdef PSREF_DEBUG
void psref_debug_barrier(void);
void psref_debug_init_lwp(struct lwp *);
#define PSREF_DEBUG_BARRIER() psref_debug_barrier()
#define PSREF_DEBUG_INIT_LWP(l) psref_debug_init_lwp((l))
#define PSREF_DEBUG_FILL_RETURN_ADDRESS0(psref, addr) do { \
(psref)->psref_debug = (addr); \
} while (0)
#define PSREF_DEBUG_FILL_RETURN_ADDRESS(psref) do { \
PSREF_DEBUG_FILL_RETURN_ADDRESS0(psref, __builtin_return_address(0));\
} while (0)
#else
#define PSREF_DEBUG_BARRIER() __nothing
#define PSREF_DEBUG_INIT_LWP(l) __nothing
#define PSREF_DEBUG_FILL_RETURN_ADDRESS0(psref, addr) __nothing
#define PSREF_DEBUG_FILL_RETURN_ADDRESS(psref) __nothing
#endif /* PSREF_DEBUG */
#endif /* _KERNEL */
#endif /* _SYS_PSREF_H */
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