/*      $NetBSD: sleeptab.h,v 1.3 2023/10/15 10:27:11 riastradh Exp $   */

/*-
 * Copyright (c) 2002, 2006, 2007, 2008, 2009, 2019, 2020
 *     The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jason R. Thorpe and Andrew Doran.
 *
 * 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_SLEEPTAB_H_
#define _SYS_SLEEPTAB_H_

#include <sys/wchan.h>

struct syncobj;

#define SLEEPTAB_HASH_SHIFT     7
#define SLEEPTAB_HASH_SIZE      (1 << SLEEPTAB_HASH_SHIFT)
#define SLEEPTAB_HASH_MASK      (SLEEPTAB_HASH_SIZE - 1)
#define SLEEPTAB_HASH(wchan)    (((uintptr_t)(wchan) >> 8) & SLEEPTAB_HASH_MASK)

LIST_HEAD(sleepq, lwp);

typedef struct sleeptab {
        sleepq_t        st_queue[SLEEPTAB_HASH_SIZE];
} sleeptab_t;

void    sleeptab_init(sleeptab_t *);

extern sleeptab_t       sleeptab;

#ifdef _KERNEL
/*
 * Find the correct sleep queue for the specified wait channel.  This
 * acquires and holds the per-queue interlock.
 */
static __inline sleepq_t *
sleeptab_lookup(sleeptab_t *st, wchan_t wchan, kmutex_t **mp)
{
        extern sleepqlock_t sleepq_locks[SLEEPTAB_HASH_SIZE];
        sleepq_t *sq;
        u_int hash;

        hash = SLEEPTAB_HASH(wchan);
        sq = &st->st_queue[hash];
        *mp = &sleepq_locks[hash].lock;
        mutex_spin_enter(*mp);
        return sq;
}

static __inline kmutex_t *
sleepq_hashlock(wchan_t wchan)
{
        extern sleepqlock_t sleepq_locks[SLEEPTAB_HASH_SIZE];
        kmutex_t *mp;

        mp = &sleepq_locks[SLEEPTAB_HASH(wchan)].lock;
        mutex_spin_enter(mp);
        return mp;
}

#define sleepq_destroy(a) __nothing

#endif

/*
 * Turnstiles, specialized sleep queues for use by kernel locks.
 */

typedef struct turnstile {
        LIST_ENTRY(turnstile)   ts_chain;       /* link on hash chain */
        struct turnstile        *ts_free;       /* turnstile free list */
        wchan_t                 ts_obj;         /* lock object */
        sleepq_t                ts_sleepq[2];   /* sleep queues */
        u_int                   ts_waiters[2];  /* count of waiters */

        /* priority inheritance */
        pri_t                   ts_eprio;
        lwp_t                   *ts_inheritor;
        SLIST_ENTRY(turnstile)  ts_pichain;
} turnstile_t;

LIST_HEAD(tschain, turnstile);

typedef struct tschain tschain_t;

#define TS_READER_Q     0               /* reader sleep queue */
#define TS_WRITER_Q     1               /* writer sleep queue */

#define TS_WAITERS(ts, q)                                               \
        (ts)->ts_waiters[(q)]

#define TS_ALL_WAITERS(ts)                                              \
        ((ts)->ts_waiters[TS_READER_Q] +                                \
         (ts)->ts_waiters[TS_WRITER_Q])

#define TS_FIRST(ts, q) (LIST_FIRST(&(ts)->ts_sleepq[(q)]))

#ifdef  _KERNEL

void    turnstile_init(void);
turnstile_t     *turnstile_lookup(wchan_t);
void    turnstile_ctor(turnstile_t *);
void    turnstile_exit(wchan_t);
void    turnstile_block(turnstile_t *, int, wchan_t, const struct syncobj *);
void    turnstile_wakeup(turnstile_t *, int, int, lwp_t *);
void    turnstile_print(volatile void *, void (*)(const char *, ...)
    __printflike(1, 2));
void    turnstile_unsleep(lwp_t *, bool);
void    turnstile_changepri(lwp_t *, pri_t);

extern struct pool turnstile_pool;
extern turnstile_t turnstile0;

#endif  /* _KERNEL */

#endif  /* _SYS_SLEEPTAB_H_ */