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      1 /*	$NetBSD: rcupdate.h,v 1.8 2021/12/19 11:49:11 riastradh Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2018 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Taylor R. Campbell.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #ifndef _LINUX_RCUPDATE_H_
     33 #define _LINUX_RCUPDATE_H_
     34 
     35 #include <sys/atomic.h>
     36 #include <sys/cdefs.h>
     37 #include <sys/systm.h>
     38 
     39 #include <linux/bug.h>
     40 
     41 #define	__rcu
     42 
     43 #define	RCU_INIT_POINTER(P, V)	((P) = (V))
     44 
     45 #define	rcu_assign_pointer(P,V)	atomic_store_release(&(P), (V))
     46 #define	rcu_dereference(P)	atomic_load_consume(&(P))
     47 #define	rcu_access_pointer(P) 	atomic_load_relaxed(&(P))
     48 
     49 #define	rcu_dereference_raw	rcu_dereference
     50 
     51 #define	rcu_dereference_protected(P, C) ({				      \
     52 	WARN_ON(!(C));							      \
     53 	(P);								      \
     54 })
     55 
     56 #define	rcu_replace_pointer(PTRP, NEWPTR, C) ({				      \
     57 	__typeof__(PTRP) __rrp_ptrp = (PTRP);				      \
     58 	__typeof__(PTRP) __rrp_oldptr =					      \
     59 		rcu_dereference_protected(__rrp_ptrp, C);		      \
     60 	rcu_assign_pointer(__rrp_ptrp, NEWPTR);				      \
     61 	__rrp_oldptr;							      \
     62 })
     63 
     64 
     65 /* kill_dependency */
     66 #define	rcu_pointer_handoff(P)	(P)
     67 
     68 struct rcu_head {
     69 	union {
     70 		void		(*callback)(struct rcu_head *);
     71 		void		*obj;
     72 	}		rcuh_u;
     73 	struct rcu_head	*rcuh_next;
     74 };
     75 
     76 #define	_kfree_rcu		linux__kfree_rcu
     77 #define	call_rcu		linux_call_rcu
     78 #define	cond_synchronize_rcu	linux_cond_synchronize_rcu
     79 #define	destroy_rcu_head	linux_destroy_rcu_head
     80 #define	init_rcu_head		linux_init_rcu_head
     81 #define	get_state_synchronize_rcu linux_get_state_synchronize_rcu
     82 #define	rcu_barrier		linux_rcu_barrier
     83 #define	synchronize_rcu		linux_synchronize_rcu
     84 #define	synchronize_rcu_expedited linux_synchronize_rcu_expedited
     85 
     86 int	linux_rcu_gc_init(void);
     87 void	linux_rcu_gc_fini(void);
     88 
     89 void	init_rcu_head(struct rcu_head *);
     90 void	destroy_rcu_head(struct rcu_head *);
     91 
     92 void	call_rcu(struct rcu_head *, void (*)(struct rcu_head *));
     93 void	rcu_barrier(void);
     94 void	synchronize_rcu(void);
     95 void	synchronize_rcu_expedited(void);
     96 
     97 unsigned long get_state_synchronize_rcu(void);
     98 void	cond_synchronize_rcu(unsigned long);
     99 
    100 void	_kfree_rcu(struct rcu_head *, void *);
    101 
    102 static inline void
    103 rcu_read_lock(void)
    104 {
    105 
    106 	kpreempt_disable();	/* implies __insn_barrier */
    107 }
    108 
    109 static inline void
    110 rcu_read_unlock(void)
    111 {
    112 
    113 	kpreempt_enable();	/* implies __insn_barrier */
    114 }
    115 
    116 #define	kfree_rcu(P, F)							      \
    117 	_kfree_rcu(&(P)->F, (P))
    118 
    119 #endif  /* _LINUX_RCUPDATE_H_ */
    120