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      1 /*	$NetBSD: sleeptab.h,v 1.3 2023/10/15 10:27:11 riastradh Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 2002, 2006, 2007, 2008, 2009, 2019, 2020
      5  *     The NetBSD Foundation, Inc.
      6  * All rights reserved.
      7  *
      8  * This code is derived from software contributed to The NetBSD Foundation
      9  * by Jason R. Thorpe and Andrew Doran.
     10  *
     11  * Redistribution and use in source and binary forms, with or without
     12  * modification, are permitted provided that the following conditions
     13  * are met:
     14  * 1. Redistributions of source code must retain the above copyright
     15  *    notice, this list of conditions and the following disclaimer.
     16  * 2. Redistributions in binary form must reproduce the above copyright
     17  *    notice, this list of conditions and the following disclaimer in the
     18  *    documentation and/or other materials provided with the distribution.
     19  *
     20  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     22  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     23  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     24  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     25  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     26  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     27  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     28  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     29  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     30  * POSSIBILITY OF SUCH DAMAGE.
     31  */
     32 
     33 #ifndef	_SYS_SLEEPTAB_H_
     34 #define	_SYS_SLEEPTAB_H_
     35 
     36 #include <sys/wchan.h>
     37 
     38 struct syncobj;
     39 
     40 #define	SLEEPTAB_HASH_SHIFT	7
     41 #define	SLEEPTAB_HASH_SIZE	(1 << SLEEPTAB_HASH_SHIFT)
     42 #define	SLEEPTAB_HASH_MASK	(SLEEPTAB_HASH_SIZE - 1)
     43 #define	SLEEPTAB_HASH(wchan)	(((uintptr_t)(wchan) >> 8) & SLEEPTAB_HASH_MASK)
     44 
     45 LIST_HEAD(sleepq, lwp);
     46 
     47 typedef struct sleeptab {
     48 	sleepq_t	st_queue[SLEEPTAB_HASH_SIZE];
     49 } sleeptab_t;
     50 
     51 void	sleeptab_init(sleeptab_t *);
     52 
     53 extern sleeptab_t	sleeptab;
     54 
     55 #ifdef _KERNEL
     56 /*
     57  * Find the correct sleep queue for the specified wait channel.  This
     58  * acquires and holds the per-queue interlock.
     59  */
     60 static __inline sleepq_t *
     61 sleeptab_lookup(sleeptab_t *st, wchan_t wchan, kmutex_t **mp)
     62 {
     63 	extern sleepqlock_t sleepq_locks[SLEEPTAB_HASH_SIZE];
     64 	sleepq_t *sq;
     65 	u_int hash;
     66 
     67 	hash = SLEEPTAB_HASH(wchan);
     68 	sq = &st->st_queue[hash];
     69 	*mp = &sleepq_locks[hash].lock;
     70 	mutex_spin_enter(*mp);
     71 	return sq;
     72 }
     73 
     74 static __inline kmutex_t *
     75 sleepq_hashlock(wchan_t wchan)
     76 {
     77 	extern sleepqlock_t sleepq_locks[SLEEPTAB_HASH_SIZE];
     78 	kmutex_t *mp;
     79 
     80 	mp = &sleepq_locks[SLEEPTAB_HASH(wchan)].lock;
     81 	mutex_spin_enter(mp);
     82 	return mp;
     83 }
     84 
     85 #define sleepq_destroy(a) __nothing
     86 
     87 #endif
     88 
     89 /*
     90  * Turnstiles, specialized sleep queues for use by kernel locks.
     91  */
     92 
     93 typedef struct turnstile {
     94 	LIST_ENTRY(turnstile)	ts_chain;	/* link on hash chain */
     95 	struct turnstile	*ts_free;	/* turnstile free list */
     96 	wchan_t			ts_obj;		/* lock object */
     97 	sleepq_t		ts_sleepq[2];	/* sleep queues */
     98 	u_int			ts_waiters[2];	/* count of waiters */
     99 
    100 	/* priority inheritance */
    101 	pri_t			ts_eprio;
    102 	lwp_t			*ts_inheritor;
    103 	SLIST_ENTRY(turnstile)	ts_pichain;
    104 } turnstile_t;
    105 
    106 LIST_HEAD(tschain, turnstile);
    107 
    108 typedef struct tschain tschain_t;
    109 
    110 #define	TS_READER_Q	0		/* reader sleep queue */
    111 #define	TS_WRITER_Q	1		/* writer sleep queue */
    112 
    113 #define	TS_WAITERS(ts, q)						\
    114 	(ts)->ts_waiters[(q)]
    115 
    116 #define	TS_ALL_WAITERS(ts)						\
    117 	((ts)->ts_waiters[TS_READER_Q] +				\
    118 	 (ts)->ts_waiters[TS_WRITER_Q])
    119 
    120 #define	TS_FIRST(ts, q)	(LIST_FIRST(&(ts)->ts_sleepq[(q)]))
    121 
    122 #ifdef	_KERNEL
    123 
    124 void	turnstile_init(void);
    125 turnstile_t	*turnstile_lookup(wchan_t);
    126 void	turnstile_ctor(turnstile_t *);
    127 void	turnstile_exit(wchan_t);
    128 void	turnstile_block(turnstile_t *, int, wchan_t, const struct syncobj *);
    129 void	turnstile_wakeup(turnstile_t *, int, int, lwp_t *);
    130 void	turnstile_print(volatile void *, void (*)(const char *, ...)
    131     __printflike(1, 2));
    132 void	turnstile_unsleep(lwp_t *, bool);
    133 void	turnstile_changepri(lwp_t *, pri_t);
    134 
    135 extern struct pool turnstile_pool;
    136 extern turnstile_t turnstile0;
    137 
    138 #endif	/* _KERNEL */
    139 
    140 #endif	/* _SYS_SLEEPTAB_H_ */
    141