xref: /f-stack/lib/ff_kern_timeout.c (revision 2317ada5)

/*-
 * Copyright (c) 1982, 1986, 1991, 1993
 *  The Regents of the University of California.  All rights reserved.
 * (c) UNIX System Laboratories, Inc.
 * All or some portions of this file are derived from material licensed
 * to the University of California by American Telephone and Telegraph
 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
 * the permission of UNIX System Laboratories, Inc.
 *
 * Copyright (c) 2010 Kip Macy. All rights reserved.
 * Copyright (c) 2013 Patrick Kelsey. All rights reserved.
 * Copyright (C) 2017-2021 THL A29 Limited, a Tencent company.
 * All rights reserved.
 *
 * 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.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 *
 *  From: @(#)kern_clock.c  8.5 (Berkeley) 1/21/94
 *
 * Derived in part from libplebnet's pn_kern_timeout.c and libuinet's uinet_timecounter.c.
 *
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "opt_callout_profiling.h"
#include "opt_ddb.h"
#if defined(__arm__)
#include "opt_timer.h"
#endif
#include "opt_rss.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/callout.h>
#include <sys/file.h>
#include <sys/interrupt.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sdt.h>
#include <sys/sleepqueue.h>
#include <sys/sysctl.h>
#include <sys/smp.h>
#include <sys/timetc.h>

SDT_PROVIDER_DEFINE(callout_execute);
SDT_PROBE_DEFINE1(callout_execute, , , callout__start, "struct callout *");
SDT_PROBE_DEFINE1(callout_execute, , , callout__end, "struct callout *");

#ifdef CALLOUT_PROFILING
static int avg_depth;
SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0,
    "Average number of items examined per softclock call. Units = 1/1000");
static int avg_gcalls;
SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0,
    "Average number of Giant callouts made per softclock call. Units = 1/1000");
static int avg_lockcalls;
SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls, CTLFLAG_RD, &avg_lockcalls, 0,
    "Average number of lock callouts made per softclock call. Units = 1/1000");
static int avg_mpcalls;
SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0,
    "Average number of MP callouts made per softclock call. Units = 1/1000");
#endif

static int ncallout;
SYSCTL_INT(_kern, OID_AUTO, ncallout, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &ncallout, 0,
    "Number of entries in callwheel and size of timeout() preallocation");

#ifdef RSS
static int pin_default_swi = 1;
static int pin_pcpu_swi = 1;
#else
static int pin_default_swi = 0;
static int pin_pcpu_swi = 0;
#endif

SYSCTL_INT(_kern, OID_AUTO, pin_default_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &pin_default_swi,
    0, "Pin the default (non-per-cpu) swi (shared with PCPU 0 swi)");
SYSCTL_INT(_kern, OID_AUTO, pin_pcpu_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &pin_pcpu_swi,
    0, "Pin the per-CPU swis (except PCPU 0, which is also default");

#define sleepq_lock(w) do {} while(0)
#define sleepq_release(w) do {} while(0)
#define sleepq_add(a, b, c, d, e) do {} while(0)
#define sleepq_wait(w, p) do {} while(0)

#define    CC_HASH_SHIFT    8

/*
 * TODO:
 *    allocate more timeout table slots when table overflows.
 */
u_int callwheelsize, callwheelmask;

/*
 * The callout cpu exec entities represent informations necessary for
 * describing the state of callouts currently running on the CPU and the ones
 * necessary for migrating callouts to the new callout cpu. In particular,
 * the first entry of the array cc_exec_entity holds informations for callout
 * running in SWI thread context, while the second one holds informations
 * for callout running directly from hardware interrupt context.
 * The cached informations are very important for deferring migration when
 * the migrating callout is already running.
 */
struct cc_exec {
    struct callout *cc_curr;
    void (*cc_drain)(void *);
    bool cc_cancel;
    bool cc_waiting;
};

/*
 * There is one struct callout_cpu per cpu, holding all relevant
 * state for the callout processing thread on the individual CPU.
 */
struct callout_cpu {
    struct mtx_padalign cc_lock;
    struct cc_exec cc_exec_entity[2];
    struct callout *cc_next;
    struct callout *cc_callout;
    struct callout_list *cc_callwheel;
    struct callout_tailq cc_expireq;
    struct callout_slist cc_callfree;
    int cc_softticks;
    void *cc_cookie;
    u_int cc_bucket;
    u_int cc_inited;
    char cc_ktr_event_name[20];
};

#define callout_migrating(c)    ((c)->c_iflags & CALLOUT_DFRMIGRATION)

#define cc_exec_curr(cc, dir)        cc->cc_exec_entity[dir].cc_curr
#define cc_exec_drain(cc, dir)       cc->cc_exec_entity[dir].cc_drain
#define cc_exec_next(cc)             cc->cc_next
#define cc_exec_cancel(cc, dir)      cc->cc_exec_entity[dir].cc_cancel
#define cc_exec_waiting(cc, dir)     cc->cc_exec_entity[dir].cc_waiting
struct callout_cpu cc_cpu;
#define CC_CPU(cpu)    &cc_cpu
#define CC_SELF()      &cc_cpu
#define CC_LOCK(cc)           mtx_lock_spin(&(cc)->cc_lock)
#define CC_UNLOCK(cc)         mtx_unlock_spin(&(cc)->cc_lock)
#define CC_LOCK_ASSERT(cc)    mtx_assert(&(cc)->cc_lock, MA_OWNED)

static int timeout_cpu;

static void callout_cpu_init(struct callout_cpu *cc, int cpu);
static void softclock_call_cc(struct callout *c, struct callout_cpu *cc,
#ifdef CALLOUT_PROFILING
    int *mpcalls, int *lockcalls, int *gcalls,
#endif
    int direct);

static MALLOC_DEFINE(M_CALLOUT, "callout", "Callout datastructures");

/**
 * Locked by cc_lock:
 *   cc_curr         - If a callout is in progress, it is cc_curr.
 *                     If cc_curr is non-NULL, threads waiting in
 *                     callout_drain() will be woken up as soon as the
 *                     relevant callout completes.
 *   cc_cancel       - Changing to 1 with both callout_lock and cc_lock held
 *                     guarantees that the current callout will not run.
 *                     The softclock() function sets this to 0 before it
 *                     drops callout_lock to acquire c_lock, and it calls
 *                     the handler only if curr_cancelled is still 0 after
 *                     cc_lock is successfully acquired.
 *   cc_waiting      - If a thread is waiting in callout_drain(), then
 *                     callout_wait is nonzero.  Set only when
 *                     cc_curr is non-NULL.
 */

/*
 * Resets the execution entity tied to a specific callout cpu.
 */
static void
cc_cce_cleanup(struct callout_cpu *cc, int direct)
{
    cc_exec_curr(cc, direct) = NULL;
    cc_exec_cancel(cc, direct) = false;
    cc_exec_waiting(cc, direct) = false;
}

/*
 * Checks if migration is requested by a specific callout cpu.
 */
static int
cc_cce_migrating(struct callout_cpu *cc, int direct)
{
    return (0);
}

/*
 * Kernel low level callwheel initialization
 * called on cpu0 during kernel startup.
 */
static void
callout_callwheel_init(void *dummy)
{
    struct callout_cpu *cc;

    /*
     * Calculate the size of the callout wheel and the preallocated
     * timeout() structures.
     * XXX: Clip callout to result of previous function of maxusers
     * maximum 384.  This is still huge, but acceptable.
     */
    memset(CC_CPU(0), 0, sizeof(cc_cpu));
    ncallout = imin(16 + maxproc + maxfiles, 18508);
    TUNABLE_INT_FETCH("kern.ncallout", &ncallout);

    /*
     * Calculate callout wheel size, should be next power of two higher
     * than 'ncallout'.
     */
    callwheelsize = 1 << fls(ncallout);
    callwheelmask = callwheelsize - 1;

    /*
     * Fetch whether we're pinning the swi's or not.
     */
    TUNABLE_INT_FETCH("kern.pin_default_swi", &pin_default_swi);
    TUNABLE_INT_FETCH("kern.pin_pcpu_swi", &pin_pcpu_swi);

    /*
     * Only cpu0 handles timeout(9) and receives a preallocation.
     *
     * XXX: Once all timeout(9) consumers are converted this can
     * be removed.
     */
    timeout_cpu = PCPU_GET(cpuid);
    cc = CC_CPU(timeout_cpu);
    cc->cc_callout = malloc(ncallout * sizeof(struct callout),
        M_CALLOUT, M_WAITOK);
    callout_cpu_init(cc, timeout_cpu);
}
SYSINIT(callwheel_init, SI_SUB_CPU, SI_ORDER_ANY, callout_callwheel_init, NULL);

/*
 * Initialize the per-cpu callout structures.
 */
static void
callout_cpu_init(struct callout_cpu *cc, int cpu)
{
    struct callout *c;
    int i;

    mtx_init(&cc->cc_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE);
    SLIST_INIT(&cc->cc_callfree);
    cc->cc_inited = 1;
    cc->cc_callwheel = malloc(sizeof(struct callout_list) * callwheelsize,
        M_CALLOUT, M_WAITOK);
    for (i = 0; i < callwheelsize; i++)
        LIST_INIT(&cc->cc_callwheel[i]);
    TAILQ_INIT(&cc->cc_expireq);
    for (i = 0; i < 2; i++)
        cc_cce_cleanup(cc, i);
    snprintf(cc->cc_ktr_event_name, sizeof(cc->cc_ktr_event_name),
        "callwheel cpu %d", cpu);
    if (cc->cc_callout == NULL)    /* Only cpu0 handles timeout(9) */
        return;
    for (i = 0; i < ncallout; i++) {
        c = &cc->cc_callout[i];
        callout_init(c, 0);
        c->c_iflags = CALLOUT_LOCAL_ALLOC;
        SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle);
    }
}

static inline u_int
callout_get_bucket(int to_ticks)
{
    return (to_ticks & callwheelmask);
}

void
callout_tick(void)
{
    struct callout_cpu *cc;
    int need_softclock;
    int bucket;

    /*
     * Process callouts at a very low cpu priority, so we don't keep the
     * relatively high clock interrupt priority any longer than necessary.
     */
    need_softclock = 0;
    cc = CC_SELF();
    mtx_lock(&cc->cc_lock);
    for (; (cc->cc_softticks - ticks) < 0; cc->cc_softticks++) {
        bucket = cc->cc_softticks & callwheelmask;
        if (!LIST_EMPTY(&cc->cc_callwheel[bucket])) {
            need_softclock = 1;
            break;
        }
    }
    mtx_unlock(&cc->cc_lock);
    /*
     * swi_sched acquires the thread lock, so we don't want to call it
     * with cc_lock held; incorrect locking order.
     */
    if (need_softclock)
        softclock(cc);
}

static struct callout_cpu *
callout_lock(struct callout *c)
{
    struct callout_cpu *cc;
    int cpu;

    for (;;) {
        cpu = c->c_cpu;
        cc = CC_CPU(cpu);
        CC_LOCK(cc);
        if (cpu == c->c_cpu)
            break;
        CC_UNLOCK(cc);
    }
    return (cc);
}

static void
callout_cc_add(struct callout *c, struct callout_cpu *cc,
    int to_ticks, void (*func)(void *), void *arg, int cpu, int flags)
{
    int bucket;

    CC_LOCK_ASSERT(cc);

    c->c_arg = arg;
    c->c_iflags |= CALLOUT_PENDING;
    c->c_iflags &= ~CALLOUT_PROCESSED;
    c->c_flags |= CALLOUT_ACTIVE;
    if (flags & C_DIRECT_EXEC)
        c->c_iflags |= CALLOUT_DIRECT;
    c->c_func = func;
    c->c_time = ticks + to_ticks;
    bucket = callout_get_bucket(c->c_time);
    LIST_INSERT_HEAD(&cc->cc_callwheel[bucket], c, c_links.le);
    if (cc->cc_bucket == bucket)
        cc_exec_next(cc) = c;
}

static void
callout_cc_del(struct callout *c, struct callout_cpu *cc)
{

    if ((c->c_iflags & CALLOUT_LOCAL_ALLOC) == 0)
        return;
    c->c_func = NULL;
    SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle);
}

static void
softclock_call_cc(struct callout *c, struct callout_cpu *cc,
#ifdef CALLOUT_PROFILING
    int *mpcalls, int *lockcalls, int *gcalls,
#endif
    int direct)
{
    struct rm_priotracker tracker;
    void (*c_func)(void *);
    void *c_arg;
    struct lock_class *class;
    struct lock_object *c_lock;
    uintptr_t lock_status;
    int c_iflags;
#if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING)
    sbintime_t sbt1, sbt2;
    struct timespec ts2;
    static sbintime_t maxdt = 2 * SBT_1MS;    /* 2 msec */
    static timeout_t *lastfunc;
#endif

    KASSERT((c->c_iflags & CALLOUT_PENDING) == CALLOUT_PENDING,
        ("softclock_call_cc: pend %p %x", c, c->c_iflags));
    KASSERT((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE,
        ("softclock_call_cc: act %p %x", c, c->c_flags));
    class = (c->c_lock != NULL) ? LOCK_CLASS(c->c_lock) : NULL;
    lock_status = 0;
    if (c->c_flags & CALLOUT_SHAREDLOCK) {
        if (class == &lock_class_rm)
            lock_status = (uintptr_t)&tracker;
        else
            lock_status = 1;
    }
    c_lock = c->c_lock;
    c_func = c->c_func;
    c_arg = c->c_arg;
    c_iflags = c->c_iflags;
    if (c->c_iflags & CALLOUT_LOCAL_ALLOC)
        c->c_iflags = CALLOUT_LOCAL_ALLOC;
    else
        c->c_iflags &= ~CALLOUT_PENDING;

    cc_exec_curr(cc, direct) = c;
    cc_exec_cancel(cc, direct) = false;
    cc_exec_drain(cc, direct) = NULL;
    CC_UNLOCK(cc);
    if (c_lock != NULL) {
        class->lc_lock(c_lock, lock_status);
        /*
         * The callout may have been cancelled
         * while we switched locks.
         */
        if (cc_exec_cancel(cc, direct)) {
            class->lc_unlock(c_lock);
            goto skip;
        }
        /* The callout cannot be stopped now. */
        cc_exec_cancel(cc, direct) = true;
        if (c_lock == &Giant.lock_object) {
#ifdef CALLOUT_PROFILING
            (*gcalls)++;
#endif
            CTR3(KTR_CALLOUT, "callout giant %p func %p arg %p",
                c, c_func, c_arg);
        } else {
#ifdef CALLOUT_PROFILING
            (*lockcalls)++;
#endif
            CTR3(KTR_CALLOUT, "callout lock %p func %p arg %p",
                c, c_func, c_arg);
        }
    } else {
#ifdef CALLOUT_PROFILING
        (*mpcalls)++;
#endif
        CTR3(KTR_CALLOUT, "callout %p func %p arg %p",
            c, c_func, c_arg);
    }
    KTR_STATE3(KTR_SCHED, "callout", cc->cc_ktr_event_name, "running",
        "func:%p", c_func, "arg:%p", c_arg, "direct:%d", direct);
#if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING)
    sbt1 = sbinuptime();
#endif
    THREAD_NO_SLEEPING();
    SDT_PROBE1(callout_execute, , , callout__start, c);
    c_func(c_arg);
    SDT_PROBE1(callout_execute, , , callout__end, c);
    THREAD_SLEEPING_OK();
#if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING)
    sbt2 = sbinuptime();
    sbt2 -= sbt1;
    if (sbt2 > maxdt) {
        if (lastfunc != c_func || sbt2 > maxdt * 2) {
            ts2 = sbttots(sbt2);
            printf(
        "Expensive timeout(9) function: %p(%p) %jd.%09ld s\n",
                c_func, c_arg, (intmax_t)ts2.tv_sec, ts2.tv_nsec);
        }
        maxdt = sbt2;
        lastfunc = c_func;
    }
#endif
    KTR_STATE0(KTR_SCHED, "callout", cc->cc_ktr_event_name, "idle");
    CTR1(KTR_CALLOUT, "callout %p finished", c);
    if ((c_iflags & CALLOUT_RETURNUNLOCKED) == 0)
        class->lc_unlock(c_lock);
skip:
    CC_LOCK(cc);
    KASSERT(cc_exec_curr(cc, direct) == c, ("mishandled cc_curr"));
    cc_exec_curr(cc, direct) = NULL;
    if (cc_exec_drain(cc, direct)) {
        void (*drain)(void *);

        drain = cc_exec_drain(cc, direct);
        cc_exec_drain(cc, direct) = NULL;
        CC_UNLOCK(cc);
        drain(c_arg);
        CC_LOCK(cc);
    }
    if (cc_exec_waiting(cc, direct)) {
        /*
         * There is someone waiting for the
         * callout to complete.
         * If the callout was scheduled for
         * migration just cancel it.
         */
        if (cc_cce_migrating(cc, direct)) {
            cc_cce_cleanup(cc, direct);

            /*
             * It should be assert here that the callout is not
             * destroyed but that is not easy.
             */
            c->c_iflags &= ~CALLOUT_DFRMIGRATION;
        }
        cc_exec_waiting(cc, direct) = false;
        CC_UNLOCK(cc);
        wakeup(&cc_exec_waiting(cc, direct));
        CC_LOCK(cc);
    } else if (cc_cce_migrating(cc, direct)) {
        KASSERT((c_iflags & CALLOUT_LOCAL_ALLOC) == 0,
            ("Migrating legacy callout %p", c));
        panic("migration should not happen");
    }
    /*
     * If the current callout is locally allocated (from
     * timeout(9)) then put it on the freelist.
     *
     * Note: we need to check the cached copy of c_iflags because
     * if it was not local, then it's not safe to deref the
     * callout pointer.
     */
    KASSERT((c_iflags & CALLOUT_LOCAL_ALLOC) == 0 ||
        c->c_iflags == CALLOUT_LOCAL_ALLOC,
        ("corrupted callout"));
    if (c_iflags & CALLOUT_LOCAL_ALLOC)
        callout_cc_del(c, cc);
}

/*
 * The callout mechanism is based on the work of Adam M. Costello and
 * George Varghese, published in a technical report entitled "Redesigning
 * the BSD Callout and Timer Facilities" and modified slightly for inclusion
 * in FreeBSD by Justin T. Gibbs.  The original work on the data structures
 * used in this implementation was published by G. Varghese and T. Lauck in
 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for
 * the Efficient Implementation of a Timer Facility" in the Proceedings of
 * the 11th ACM Annual Symposium on Operating Systems Principles,
 * Austin, Texas Nov 1987.
 */

/*
 * Software (low priority) clock interrupt.
 * Run periodic events from timeout queue.
 */
void
softclock(void *arg)
{
    struct callout *c;
    struct callout_cpu *cc;
    struct callout_list *sc;
    int curticks;
#ifdef CALLOUT_PROFILING
    int depth = 0, gcalls = 0, mpcalls = 0, lockcalls = 0;
#endif

    cc = (struct callout_cpu *)arg;
    CC_LOCK(cc);

    while (cc->cc_softticks != ticks) {
        /*
         * cc_softticks may be modified by hard clock, so cache
         * it while we work on a given bucket.
         */
        curticks = cc->cc_softticks;
        cc->cc_softticks++;
        sc = &cc->cc_callwheel[curticks & callwheelmask];
        c = LIST_FIRST(sc);
        while (c) {
#ifdef CALLOUT_PROFILING
            depth++;
#endif
            if (c->c_time != curticks) {
                c = LIST_NEXT(c, c_links.le);
            } else {
                cc_exec_next(cc) =
                    LIST_NEXT(c, c_links.le);
                cc->cc_bucket = callout_get_bucket(curticks);
                LIST_REMOVE(c, c_links.le);
                softclock_call_cc(c, cc,
#ifdef CALLOUT_PROFILING
                    &mpcalls, &lockcalls, &gcalls,
#endif
                    1);
                c = cc_exec_next(cc);
                cc_exec_next(cc) = NULL;
            }
        }
    }

#ifdef CALLOUT_PROFILING
    avg_depth += (depth * 1000 - avg_depth) >> 8;
    avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8;
    avg_lockcalls += (lockcalls * 1000 - avg_lockcalls) >> 8;
    avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8;
#endif
    CC_UNLOCK(cc);
}

#if 0
/*
 * timeout --
 *    Execute a function after a specified length of time.
 *
 * untimeout --
 *    Cancel previous timeout function call.
 *
 * callout_handle_init --
 *    Initialize a handle so that using it with untimeout is benign.
 *
 *    See AT&T BCI Driver Reference Manual for specification.  This
 *    implementation differs from that one in that although an
 *    identification value is returned from timeout, the original
 *    arguments to timeout as well as the identifier are used to
 *    identify entries for untimeout.
 */
struct callout_handle
timeout(timeout_t *ftn, void *arg, int to_ticks)
{
    struct callout_cpu *cc;
    struct callout *new;
    struct callout_handle handle;

    cc = CC_CPU(timeout_cpu);
    CC_LOCK(cc);
    /* Fill in the next free callout structure. */
    new = SLIST_FIRST(&cc->cc_callfree);
    if (new == NULL)
        /* XXX Attempt to malloc first */
        panic("timeout table full");
    SLIST_REMOVE_HEAD(&cc->cc_callfree, c_links.sle);
    callout_reset(new, to_ticks, ftn, arg);
    handle.callout = new;
    CC_UNLOCK(cc);

    return (handle);
}

void
untimeout(timeout_t *ftn, void *arg, struct callout_handle handle)
{
    struct callout_cpu *cc;

    /*
     * Check for a handle that was initialized
     * by callout_handle_init, but never used
     * for a real timeout.
     */
    if (handle.callout == NULL)
        return;

    cc = callout_lock(handle.callout);
    if (handle.callout->c_func == ftn && handle.callout->c_arg == arg)
        callout_stop(handle.callout);
    CC_UNLOCK(cc);
}

void
callout_handle_init(struct callout_handle *handle)
{
    handle->callout = NULL;
}
#endif

/*
 * New interface; clients allocate their own callout structures.
 *
 * callout_reset() - establish or change a timeout
 * callout_stop() - disestablish a timeout
 * callout_init() - initialize a callout structure so that it can
 *    safely be passed to callout_reset() and callout_stop()
 *
 * <sys/callout.h> defines three convenience macros:
 *
 * callout_active() - returns truth if callout has not been stopped,
 *    drained, or deactivated since the last time the callout was
 *    reset.
 * callout_pending() - returns truth if callout is still waiting for timeout
 * callout_deactivate() - marks the callout as having been serviced
 */
int
callout_reset_tick_on(struct callout *c, int to_ticks,
    void (*ftn)(void *), void *arg, int cpu, int flags)
{
    struct callout_cpu *cc;
    int cancelled, direct;
    int ignore_cpu=0;

    cancelled = 0;
    if (cpu == -1) {
        ignore_cpu = 1;
    } else if ((cpu >= MAXCPU) ||
           ((CC_CPU(cpu))->cc_inited == 0)) {
        /* Invalid CPU spec */
        panic("Invalid CPU in callout %d", cpu);
    }

    /*
     * This flag used to be added by callout_cc_add, but the
     * first time you call this we could end up with the
     * wrong direct flag if we don't do it before we add.
     */
    if (flags & C_DIRECT_EXEC) {
        direct = 1;
    } else {
        direct = 0;
    }
    KASSERT(!direct || c->c_lock == NULL,
        ("%s: direct callout %p has lock", __func__, c));
    cc = callout_lock(c);
    /*
     * Don't allow migration of pre-allocated callouts lest they
     * become unbalanced or handle the case where the user does
     * not care.
     */
    if ((c->c_iflags & CALLOUT_LOCAL_ALLOC) ||
        ignore_cpu) {
        cpu = c->c_cpu;
    }

    if (cc_exec_curr(cc, direct) == c) {
        /*
         * We're being asked to reschedule a callout which is
         * currently in progress.  If there is a lock then we
         * can cancel the callout if it has not really started.
         */
        if (c->c_lock != NULL && !cc_exec_cancel(cc, direct))
            cancelled = cc_exec_cancel(cc, direct) = true;
        if (cc_exec_waiting(cc, direct)) {
            /*
             * Someone has called callout_drain to kill this
             * callout.  Don't reschedule.
             */
            CTR4(KTR_CALLOUT, "%s %p func %p arg %p",
                cancelled ? "cancelled" : "failed to cancel",
                c, c->c_func, c->c_arg);
            CC_UNLOCK(cc);
            return (cancelled);
        }
    }
    if (c->c_iflags & CALLOUT_PENDING) {
        if ((c->c_iflags & CALLOUT_PROCESSED) == 0) {
            if (cc_exec_next(cc) == c)
                cc_exec_next(cc) = LIST_NEXT(c, c_links.le);
            LIST_REMOVE(c, c_links.le);
        } else {
            TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe);
        }
        cancelled = 1;
        c->c_iflags &= ~ CALLOUT_PENDING;
        c->c_flags &= ~ CALLOUT_ACTIVE;
    }

    if (to_ticks <= 0)
        to_ticks = 1;

    callout_cc_add(c, cc, to_ticks, ftn, arg, cpu, flags);
    CTR5(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d",
        cancelled ? "re" : "", c, c->c_func, c->c_arg, to_ticks);
    CC_UNLOCK(cc);

    return (cancelled);
}

/*
 * Common idioms that can be optimized in the future.
 */
int
callout_schedule_on(struct callout *c, int to_ticks, int cpu)
{
    return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, cpu);
}

int
callout_schedule(struct callout *c, int to_ticks)
{
    return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, c->c_cpu);
}

int
_callout_stop_safe(struct callout *c, int flags, void (*drain)(void *))
{
    struct callout_cpu *cc, *old_cc;
    struct lock_class *class;
    int direct, sq_locked, use_lock;
    int cancelled, not_on_a_list;

    if ((flags & CS_DRAIN) != 0)
        WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, c->c_lock,
            "calling %s", __func__);

    /*
     * Some old subsystems don't hold Giant while running a callout_stop(),
     * so just discard this check for the moment.
     */
    if ((flags & CS_DRAIN) == 0 && c->c_lock != NULL) {
        if (c->c_lock == &Giant.lock_object)
            use_lock = mtx_owned(&Giant);
        else {
            use_lock = 1;
            class = LOCK_CLASS(c->c_lock);
            class->lc_assert(c->c_lock, LA_XLOCKED);
        }
    } else
        use_lock = 0;
    if (c->c_iflags & CALLOUT_DIRECT) {
        direct = 1;
    } else {
        direct = 0;
    }
    sq_locked = 0;
    old_cc = NULL;
again:
    cc = callout_lock(c);

    if ((c->c_iflags & (CALLOUT_DFRMIGRATION | CALLOUT_PENDING)) ==
        (CALLOUT_DFRMIGRATION | CALLOUT_PENDING) &&
        ((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE)) {
        /*
         * Special case where this slipped in while we
         * were migrating *as* the callout is about to
         * execute. The caller probably holds the lock
         * the callout wants.
         *
         * Get rid of the migration first. Then set
         * the flag that tells this code *not* to
         * try to remove it from any lists (its not
         * on one yet). When the callout wheel runs,
         * it will ignore this callout.
         */
        c->c_iflags &= ~CALLOUT_PENDING;
        c->c_flags &= ~CALLOUT_ACTIVE;
        not_on_a_list = 1;
    } else {
        not_on_a_list = 0;
    }

    /*
     * If the callout was migrating while the callout cpu lock was
     * dropped,  just drop the sleepqueue lock and check the states
     * again.
     */
    if (sq_locked != 0 && cc != old_cc) {
        panic("migration should not happen");
    }

    /*
     * If the callout is running, try to stop it or drain it.
     */
    if (cc_exec_curr(cc, direct) == c) {
        /*
         * Succeed we to stop it or not, we must clear the
         * active flag - this is what API users expect.
         */
        c->c_flags &= ~CALLOUT_ACTIVE;

        if ((flags & CS_DRAIN) != 0) {
            /*
             * The current callout is running (or just
             * about to run) and blocking is allowed, so
             * just wait for the current invocation to
             * finish.
             */
            while (cc_exec_curr(cc, direct) == c) {
                /*
                 * Use direct calls to sleepqueue interface
                 * instead of cv/msleep in order to avoid
                 * a LOR between cc_lock and sleepqueue
                 * chain spinlocks.  This piece of code
                 * emulates a msleep_spin() call actually.
                 *
                 * If we already have the sleepqueue chain
                 * locked, then we can safely block.  If we
                 * don't already have it locked, however,
                 * we have to drop the cc_lock to lock
                 * it.  This opens several races, so we
                 * restart at the beginning once we have
                 * both locks.  If nothing has changed, then
                 * we will end up back here with sq_locked
                 * set.
                 */
                if (!sq_locked) {
                    CC_UNLOCK(cc);
                    sleepq_lock(
                        &cc_exec_waiting(cc, direct));
                    sq_locked = 1;
                    old_cc = cc;
                    goto again;
                }

                /*
                 * Migration could be cancelled here, but
                 * as long as it is still not sure when it
                 * will be packed up, just let softclock()
                 * take care of it.
                 */
                cc_exec_waiting(cc, direct) = true;
                DROP_GIANT();
                CC_UNLOCK(cc);
                sleepq_add(
                    &cc_exec_waiting(cc, direct),
                    &cc->cc_lock.lock_object, "codrain",
                    SLEEPQ_SLEEP, 0);
                sleepq_wait(
                    &cc_exec_waiting(cc, direct),
                         0);
                sq_locked = 0;
                old_cc = NULL;

                /* Reacquire locks previously released. */
                PICKUP_GIANT();
                CC_LOCK(cc);
            }
        } else if (use_lock &&
               !cc_exec_cancel(cc, direct) && (drain == NULL)) {

            /*
             * The current callout is waiting for its
             * lock which we hold.  Cancel the callout
             * and return.  After our caller drops the
             * lock, the callout will be skipped in
             * softclock(). This *only* works with a
             * callout_stop() *not* callout_drain() or
             * callout_async_drain().
             */
            cc_exec_cancel(cc, direct) = true;
            CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p",
                c, c->c_func, c->c_arg);
            KASSERT(!cc_cce_migrating(cc, direct),
                ("callout wrongly scheduled for migration"));
            if (callout_migrating(c)) {
                c->c_iflags &= ~CALLOUT_DFRMIGRATION;
            }
            CC_UNLOCK(cc);
            KASSERT(!sq_locked, ("sleepqueue chain locked"));
            return (1);
        } else if (callout_migrating(c)) {
            /*
             * The callout is currently being serviced
             * and the "next" callout is scheduled at
             * its completion with a migration. We remove
             * the migration flag so it *won't* get rescheduled,
             * but we can't stop the one thats running so
             * we return 0.
             */
            c->c_iflags &= ~CALLOUT_DFRMIGRATION;
            CTR3(KTR_CALLOUT, "postponing stop %p func %p arg %p",
                c, c->c_func, c->c_arg);
             if (drain) {
                cc_exec_drain(cc, direct) = drain;
            }
            CC_UNLOCK(cc);
            return ((flags & CS_EXECUTING) != 0);
        }
        CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
            c, c->c_func, c->c_arg);
        if (drain) {
            cc_exec_drain(cc, direct) = drain;
        }
        KASSERT(!sq_locked, ("sleepqueue chain still locked"));
        cancelled = ((flags & CS_EXECUTING) != 0);
    } else
        cancelled = 1;

    if (sq_locked)
        sleepq_release(&cc_exec_waiting(cc, direct));

    if ((c->c_iflags & CALLOUT_PENDING) == 0) {
        CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
            c, c->c_func, c->c_arg);
        /*
         * For not scheduled and not executing callout return
         * negative value.
         */
        if (cc_exec_curr(cc, direct) != c)
            cancelled = -1;
        CC_UNLOCK(cc);
        return (cancelled);
    }

    c->c_iflags &= ~CALLOUT_PENDING;
    c->c_flags &= ~CALLOUT_ACTIVE;

    CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p",
        c, c->c_func, c->c_arg);
    if (not_on_a_list == 0) {
        if ((c->c_iflags & CALLOUT_PROCESSED) == 0) {
            if (cc_exec_next(cc) == c)
                cc_exec_next(cc) = LIST_NEXT(c, c_links.le);
            LIST_REMOVE(c, c_links.le);
        } else {
            TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe);
        }
    }
    callout_cc_del(c, cc);
    CC_UNLOCK(cc);
    return (cancelled);
}

void
callout_init(struct callout *c, int mpsafe)
{
    bzero(c, sizeof *c);
    if (mpsafe) {
        c->c_lock = NULL;
        c->c_iflags = CALLOUT_RETURNUNLOCKED;
    } else {
        c->c_lock = &Giant.lock_object;
        c->c_iflags = 0;
    }
    c->c_cpu = timeout_cpu;
}

void
_callout_init_lock(struct callout *c, struct lock_object *lock, int flags)
{
    bzero(c, sizeof *c);
    c->c_lock = lock;
    KASSERT((flags & ~(CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK)) == 0,
        ("callout_init_lock: bad flags %d", flags));
    KASSERT(lock != NULL || (flags & CALLOUT_RETURNUNLOCKED) == 0,
        ("callout_init_lock: CALLOUT_RETURNUNLOCKED with no lock"));
    KASSERT(lock == NULL || !(LOCK_CLASS(lock)->lc_flags &
        (LC_SPINLOCK | LC_SLEEPABLE)), ("%s: invalid lock class",
        __func__));
    c->c_iflags = flags & (CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK);
    c->c_cpu = timeout_cpu;
}

#ifdef APM_FIXUP_CALLTODO
/*
 * Adjust the kernel calltodo timeout list.  This routine is used after
 * an APM resume to recalculate the calltodo timer list values with the
 * number of hz's we have been sleeping.  The next hardclock() will detect
 * that there are fired timers and run softclock() to execute them.
 *
 * Please note, I have not done an exhaustive analysis of what code this
 * might break.  I am motivated to have my select()'s and alarm()'s that
 * have expired during suspend firing upon resume so that the applications
 * which set the timer can do the maintanence the timer was for as close
 * as possible to the originally intended time.  Testing this code for a
 * week showed that resuming from a suspend resulted in 22 to 25 timers
 * firing, which seemed independent on whether the suspend was 2 hours or
 * 2 days.  Your milage may vary.   - Ken Key <[email protected]>
 */
void
adjust_timeout_calltodo(struct timeval *time_change)
{
    register struct callout *p;
    unsigned long delta_ticks;

    /*
     * How many ticks were we asleep?
     * (stolen from tvtohz()).
     */

    /* Don't do anything */
    if (time_change->tv_sec < 0)
        return;
    else if (time_change->tv_sec <= LONG_MAX / 1000000)
        delta_ticks = howmany(time_change->tv_sec * 1000000 +
            time_change->tv_usec, tick) + 1;
    else if (time_change->tv_sec <= LONG_MAX / hz)
        delta_ticks = time_change->tv_sec * hz +
            howmany(time_change->tv_usec, tick) + 1;
    else
        delta_ticks = LONG_MAX;

    if (delta_ticks > INT_MAX)
        delta_ticks = INT_MAX;

    /*
     * Now rip through the timer calltodo list looking for timers
     * to expire.
     */

    /* don't collide with softclock() */
    CC_LOCK(cc);
    for (p = calltodo.c_next; p != NULL; p = p->c_next) {
        p->c_time -= delta_ticks;

        /* Break if the timer had more time on it than delta_ticks */
        if (p->c_time > 0)
            break;

        /* take back the ticks the timer didn't use (p->c_time <= 0) */
        delta_ticks = -p->c_time;
    }
    CC_UNLOCK(cc);

    return;
}
#endif /* APM_FIXUP_CALLTODO */

static int
flssbt(sbintime_t sbt)
{

    sbt += (uint64_t)sbt >> 1;
    if (sizeof(long) >= sizeof(sbintime_t))
        return (flsl(sbt));
    if (sbt >= SBT_1S)
        return (flsl(((uint64_t)sbt) >> 32) + 32);
    return (flsl(sbt));
}

/*
 * Dump immediate statistic snapshot of the scheduled callouts.
 */
static int
sysctl_kern_callout_stat(SYSCTL_HANDLER_ARGS)
{
    struct callout *tmp;
    struct callout_cpu *cc;
    struct callout_list *sc;
    int st, maxt, tick, now;
    sbintime_t medt;
    int ct[64], ccpbk[32];
    int error, val, i, count, tcum, pcum, maxc, c, medc;

    val = 0;
    error = sysctl_handle_int(oidp, &val, 0, req);
    if (error != 0 || req->newptr == NULL)
        return (error);
    count = maxc = 0;
    st = maxt = 0;
    bzero(ccpbk, sizeof(ccpbk));
    bzero(ct, sizeof(ct));
    now = ticks;

    cc = CC_CPU(timeout_cpu);
    CC_LOCK(cc);
    for (i = 0; i < callwheelsize; i++) {
        sc = &cc->cc_callwheel[i];
        c = 0;
        LIST_FOREACH(tmp, sc, c_links.le) {
            c++;
            tick = tmp->c_time - now;
            if (tick < 0)
                tick = 0;
            st += tick*(1000/hz);
            if (tick > maxt)
                maxt = tick;
            ct[flssbt(tick)]++;
        }
        if (c > maxc)
            maxc = c;
        ccpbk[fls(c + c / 2)]++;
        count += c;
    }
    CC_UNLOCK(cc);

    for (i = 0, tcum = 0; i < 64 && tcum < count / 2; i++)
        tcum += ct[i];
    medt = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0;
    for (i = 0, c = 0; i < 32 && c < count / 2; i++)
        c += ccpbk[i];
    medc = (i >= 2) ? (1 << (i - 2)) : 0;

    printf("Scheduled callouts statistic snapshot:\n");
    printf("  Callouts: %6d  Buckets: %6d*%-3d  Bucket size: 0.%06ds\n",
        count, callwheelsize, mp_ncpus, 1000000 >> CC_HASH_SHIFT);
    printf("  C/Bk: med %5d         avg %6d.%06jd  max %6d\n",
        medc,
        count / callwheelsize / mp_ncpus,
        (uint64_t)count * 1000000 / callwheelsize / mp_ncpus % 1000000,
        maxc);
    printf("  Time: med %5jd.%06jds avg %6d.%06ds max %ds\n",
        medt / SBT_1S, (medt & 0xffffffff) * 1000000 >> 32,
        st / count / 1000, (st / count) % 1000, maxt);
    printf("  Distribution:       \tbuckets\t   time\t   tcum\n");
    for (i = 0, tcum = pcum = 0; i < 64; i++) {
        if (ct[i] == 0)
            continue;
        sbintime_t t;
        t = (i != 0) ? (((sbintime_t)1) << (i - 1)) : 0;
        tcum += ct[i];
        printf("  %10jd.%06jds\t 2**%d\t%7d\t%7d\n",
            t / SBT_1S, (t & 0xffffffff) * 1000000 >> 32,
            i - 1 - (32 - CC_HASH_SHIFT), ct[i], tcum);
    }
    return (error);
}
SYSCTL_PROC(_kern, OID_AUTO, callout_stat,
    CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
    0, 0, sysctl_kern_callout_stat, "I",
    "Dump immediate statistic snapshot of the scheduled callouts");

#ifdef FSTACK
void ff_hardclock(void);

void
ff_hardclock(void)
{
    atomic_add_int(&ticks, 1);
    callout_tick();
    tc_ticktock(1);
    cpu_tick_calibration();

#ifdef DEVICE_POLLING
    hardclock_device_poll();    /* this is very short and quick */
#endif /* DEVICE_POLLING */
}

static unsigned int
ff_tc_get_timecount(struct timecounter *tc)
{
    uint64_t ns;
    ns = ff_get_tsc_ns();
    return ((ns * tc->tc_frequency) / ff_NSEC_PER_SEC);
}

static struct timecounter ff_timecounter = {
    ff_tc_get_timecount, 0, ~0u, 100, "ff_clock", 1
};

static void
ff_tc_init(void)
{
    ff_timecounter.tc_frequency = hz;
    tc_init(&ff_timecounter);
}
SYSINIT(ff_tc, SI_SUB_SMP, SI_ORDER_ANY, ff_tc_init, NULL);
#endif