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rcupdate.h revision 1.2 
      1 /*	$NetBSD: rcupdate.h,v 1.2 2021/12/19 01:46:01 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 #define	__rcu
     40 
     41 #define	RCU_INIT_POINTER(P, V)	((P) = (V))
     42 
     43 #define	rcu_assign_pointer(P, V) do {					      \
     44 	__typeof__(*(P)) *__rcu_assign_pointer_tmp = (V);		      \
     45 	membar_exit();							      \
     46 	(P) = __rcu_assign_pointer_tmp;					      \
     47 } while (0)
     48 
     49 #define	rcu_dereference(P) ({						      \
     50 	__typeof__(*(P)) *__rcu_dereference_tmp = (P);			      \
     51 	membar_datadep_consumer();					      \
     52 	__rcu_dereference_tmp;						      \
     53 })
     54 
     55 #define	rcu_dereference_raw	rcu_dereference
     56 
     57 #define	rcu_dereference_protected(P, C) ({				      \
     58 	WARN_ON(!(C));							      \
     59 	(P);								      \
     60 })
     61 
     62 #define	rcu_access_pointer(P) ({					      \
     63 	__typeof__(*(P)) *__rcu_access_pointer_tmp = (P);		      \
     64 	__insn_barrier();						      \
     65 	__rcu_access_pointer_tmp;					      \
     66 })
     67 
     68 /* kill_dependency */
     69 #define	rcu_pointer_handoff(P)	(P)
     70 
     71 struct rcu_head {
     72 	union {
     73 		void		(*callback)(struct rcu_head *);
     74 		void		*obj;
     75 	}		rcuh_u;
     76 	struct rcu_head	*rcuh_next;
     77 };
     78 
     79 #define	_kfree_rcu		linux__kfree_rcu
     80 #define	call_rcu		linux_call_rcu
     81 #define	rcu_barrier		linux_rcu_barrier
     82 #define	synchronize_rcu		linux_synchronize_rcu
     83 
     84 int	linux_rcu_gc_init(void);
     85 void	linux_rcu_gc_fini(void);
     86 
     87 void	call_rcu(struct rcu_head *, void (*)(struct rcu_head *));
     88 void	rcu_barrier(void);
     89 void	synchronize_rcu(void);
     90 
     91 void	_kfree_rcu(struct rcu_head *, void *);
     92 
     93 static inline void
     94 rcu_read_lock(void)
     95 {
     96 
     97 	kpreempt_disable();	/* implies __insn_barrier */
     98 }
     99 
    100 static inline void
    101 rcu_read_unlock(void)
    102 {
    103 
    104 	kpreempt_enable();	/* implies __insn_barrier */
    105 }
    106 
    107 #define	kfree_rcu(P, F)							      \
    108 	_kfree_rcu(&(P)->F, (P))
    109 
    110 #endif  /* _LINUX_RCUPDATE_H_ */
    111