565 lines
16 KiB
C
565 lines
16 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1991, 1993
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/callout.h>
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#include <sys/condvar.h>
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#include <sys/kernel.h>
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#include <sys/ktr.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/sysctl.h>
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static int avg_depth;
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SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0,
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"Average number of items examined per softclock call. Units = 1/1000");
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static int avg_gcalls;
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SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0,
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"Average number of Giant callouts made per softclock call. Units = 1/1000");
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static int avg_mpcalls;
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SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0,
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"Average number of MP callouts made per softclock call. Units = 1/1000");
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/*
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* TODO:
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* allocate more timeout table slots when table overflows.
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*/
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/* Exported to machdep.c and/or kern_clock.c. */
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struct callout *callout;
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struct callout_list callfree;
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int callwheelsize, callwheelbits, callwheelmask;
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struct callout_tailq *callwheel;
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int softticks; /* Like ticks, but for softclock(). */
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struct mtx callout_lock;
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#ifdef DIAGNOSTIC
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struct mtx dont_sleep_in_callout;
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#endif
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static struct callout *nextsoftcheck; /* Next callout to be checked. */
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/**
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* Locked by callout_lock:
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* curr_callout - If a callout is in progress, it is curr_callout.
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* If curr_callout is non-NULL, threads waiting on
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* callout_wait will be woken up as soon as the
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* relevant callout completes.
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* wakeup_ctr - Incremented every time a thread wants to wait
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* for a callout to complete. Modified only when
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* curr_callout is non-NULL.
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* wakeup_needed - If a thread is waiting on callout_wait, then
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* wakeup_needed is nonzero. Increased only when
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* cutt_callout is non-NULL.
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*/
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static struct callout *curr_callout;
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static int wakeup_ctr;
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static int wakeup_needed;
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/**
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* Locked by callout_wait_lock:
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* callout_wait - If wakeup_needed is set, callout_wait will be
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* triggered after the current callout finishes.
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* wakeup_done_ctr - Set to the current value of wakeup_ctr after
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* callout_wait is triggered.
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*/
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static struct mtx callout_wait_lock;
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static struct cv callout_wait;
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static int wakeup_done_ctr;
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/*
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* kern_timeout_callwheel_alloc() - kernel low level callwheel initialization
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*
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* This code is called very early in the kernel initialization sequence,
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* and may be called more then once.
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*/
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caddr_t
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kern_timeout_callwheel_alloc(caddr_t v)
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{
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/*
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* Calculate callout wheel size
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*/
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for (callwheelsize = 1, callwheelbits = 0;
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callwheelsize < ncallout;
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callwheelsize <<= 1, ++callwheelbits)
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;
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callwheelmask = callwheelsize - 1;
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callout = (struct callout *)v;
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v = (caddr_t)(callout + ncallout);
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callwheel = (struct callout_tailq *)v;
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v = (caddr_t)(callwheel + callwheelsize);
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return(v);
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}
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/*
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* kern_timeout_callwheel_init() - initialize previously reserved callwheel
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* space.
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*
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* This code is called just once, after the space reserved for the
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* callout wheel has been finalized.
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*/
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void
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kern_timeout_callwheel_init(void)
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{
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int i;
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SLIST_INIT(&callfree);
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for (i = 0; i < ncallout; i++) {
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callout_init(&callout[i], 0);
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callout[i].c_flags = CALLOUT_LOCAL_ALLOC;
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SLIST_INSERT_HEAD(&callfree, &callout[i], c_links.sle);
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}
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for (i = 0; i < callwheelsize; i++) {
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TAILQ_INIT(&callwheel[i]);
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}
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mtx_init(&callout_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE);
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#ifdef DIAGNOSTIC
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mtx_init(&dont_sleep_in_callout, "dont_sleep_in_callout", NULL, MTX_DEF);
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#endif
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mtx_init(&callout_wait_lock, "callout_wait_lock", NULL, MTX_DEF);
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cv_init(&callout_wait, "callout_wait");
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}
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/*
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* The callout mechanism is based on the work of Adam M. Costello and
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* George Varghese, published in a technical report entitled "Redesigning
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* the BSD Callout and Timer Facilities" and modified slightly for inclusion
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* in FreeBSD by Justin T. Gibbs. The original work on the data structures
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* used in this implementation was published by G. Varghese and T. Lauck in
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* the paper "Hashed and Hierarchical Timing Wheels: Data Structures for
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* the Efficient Implementation of a Timer Facility" in the Proceedings of
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* the 11th ACM Annual Symposium on Operating Systems Principles,
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* Austin, Texas Nov 1987.
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*/
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/*
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* Software (low priority) clock interrupt.
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* Run periodic events from timeout queue.
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*/
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void
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softclock(void *dummy)
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{
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struct callout *c;
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struct callout_tailq *bucket;
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int curticks;
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int steps; /* #steps since we last allowed interrupts */
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int depth;
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int mpcalls;
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int gcalls;
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int wakeup_cookie;
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#ifdef DIAGNOSTIC
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struct bintime bt1, bt2;
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struct timespec ts2;
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static uint64_t maxdt = 36893488147419102LL; /* 2 msec */
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static timeout_t *lastfunc;
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#endif
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#ifndef MAX_SOFTCLOCK_STEPS
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#define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */
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#endif /* MAX_SOFTCLOCK_STEPS */
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mpcalls = 0;
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gcalls = 0;
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depth = 0;
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steps = 0;
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mtx_lock_spin(&callout_lock);
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while (softticks != ticks) {
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softticks++;
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/*
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* softticks may be modified by hard clock, so cache
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* it while we work on a given bucket.
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*/
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curticks = softticks;
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bucket = &callwheel[curticks & callwheelmask];
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c = TAILQ_FIRST(bucket);
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while (c) {
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depth++;
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if (c->c_time != curticks) {
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c = TAILQ_NEXT(c, c_links.tqe);
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++steps;
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if (steps >= MAX_SOFTCLOCK_STEPS) {
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nextsoftcheck = c;
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/* Give interrupts a chance. */
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mtx_unlock_spin(&callout_lock);
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; /* nothing */
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mtx_lock_spin(&callout_lock);
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c = nextsoftcheck;
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steps = 0;
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}
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} else {
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void (*c_func)(void *);
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void *c_arg;
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int c_flags;
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nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
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TAILQ_REMOVE(bucket, c, c_links.tqe);
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c_func = c->c_func;
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c_arg = c->c_arg;
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c_flags = c->c_flags;
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c->c_func = NULL;
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if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
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c->c_flags = CALLOUT_LOCAL_ALLOC;
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SLIST_INSERT_HEAD(&callfree, c,
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c_links.sle);
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} else {
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c->c_flags =
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(c->c_flags & ~CALLOUT_PENDING);
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}
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curr_callout = c;
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mtx_unlock_spin(&callout_lock);
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if (!(c_flags & CALLOUT_MPSAFE)) {
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mtx_lock(&Giant);
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gcalls++;
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CTR1(KTR_CALLOUT, "callout %p", c_func);
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} else {
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mpcalls++;
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CTR1(KTR_CALLOUT, "callout mpsafe %p",
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c_func);
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}
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#ifdef DIAGNOSTIC
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binuptime(&bt1);
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mtx_lock(&dont_sleep_in_callout);
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#endif
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c_func(c_arg);
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#ifdef DIAGNOSTIC
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mtx_unlock(&dont_sleep_in_callout);
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binuptime(&bt2);
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bintime_sub(&bt2, &bt1);
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if (bt2.frac > maxdt) {
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if (lastfunc != c_func ||
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bt2.frac > maxdt * 2) {
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bintime2timespec(&bt2, &ts2);
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printf(
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"Expensive timeout(9) function: %p(%p) %jd.%09ld s\n",
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c_func, c_arg,
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(intmax_t)ts2.tv_sec,
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ts2.tv_nsec);
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}
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maxdt = bt2.frac;
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lastfunc = c_func;
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}
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#endif
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if (!(c_flags & CALLOUT_MPSAFE))
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mtx_unlock(&Giant);
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mtx_lock_spin(&callout_lock);
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curr_callout = NULL;
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if (wakeup_needed) {
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/*
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* There might be someone waiting
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* for the callout to complete.
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*/
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wakeup_cookie = wakeup_ctr;
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mtx_unlock_spin(&callout_lock);
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mtx_lock(&callout_wait_lock);
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cv_broadcast(&callout_wait);
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wakeup_done_ctr = wakeup_cookie;
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mtx_unlock(&callout_wait_lock);
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mtx_lock_spin(&callout_lock);
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wakeup_needed = 0;
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}
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steps = 0;
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c = nextsoftcheck;
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}
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}
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}
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avg_depth += (depth * 1000 - avg_depth) >> 8;
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avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8;
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avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8;
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nextsoftcheck = NULL;
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mtx_unlock_spin(&callout_lock);
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}
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/*
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* timeout --
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* Execute a function after a specified length of time.
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*
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* untimeout --
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* Cancel previous timeout function call.
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*
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* callout_handle_init --
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* Initialize a handle so that using it with untimeout is benign.
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*
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* See AT&T BCI Driver Reference Manual for specification. This
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* implementation differs from that one in that although an
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* identification value is returned from timeout, the original
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* arguments to timeout as well as the identifier are used to
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* identify entries for untimeout.
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*/
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struct callout_handle
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timeout(ftn, arg, to_ticks)
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timeout_t *ftn;
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void *arg;
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int to_ticks;
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{
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struct callout *new;
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struct callout_handle handle;
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mtx_lock_spin(&callout_lock);
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/* Fill in the next free callout structure. */
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new = SLIST_FIRST(&callfree);
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if (new == NULL)
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/* XXX Attempt to malloc first */
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panic("timeout table full");
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SLIST_REMOVE_HEAD(&callfree, c_links.sle);
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callout_reset(new, to_ticks, ftn, arg);
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handle.callout = new;
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mtx_unlock_spin(&callout_lock);
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return (handle);
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}
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void
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untimeout(ftn, arg, handle)
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timeout_t *ftn;
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void *arg;
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struct callout_handle handle;
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{
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/*
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* Check for a handle that was initialized
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* by callout_handle_init, but never used
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* for a real timeout.
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*/
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if (handle.callout == NULL)
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return;
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mtx_lock_spin(&callout_lock);
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if (handle.callout->c_func == ftn && handle.callout->c_arg == arg)
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callout_stop(handle.callout);
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mtx_unlock_spin(&callout_lock);
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}
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void
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callout_handle_init(struct callout_handle *handle)
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{
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handle->callout = NULL;
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}
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/*
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* New interface; clients allocate their own callout structures.
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*
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* callout_reset() - establish or change a timeout
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* callout_stop() - disestablish a timeout
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* callout_init() - initialize a callout structure so that it can
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* safely be passed to callout_reset() and callout_stop()
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*
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* <sys/callout.h> defines three convenience macros:
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*
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* callout_active() - returns truth if callout has not been serviced
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* callout_pending() - returns truth if callout is still waiting for timeout
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* callout_deactivate() - marks the callout as having been serviced
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*/
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void
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callout_reset(c, to_ticks, ftn, arg)
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struct callout *c;
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int to_ticks;
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void (*ftn)(void *);
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void *arg;
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{
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mtx_lock_spin(&callout_lock);
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if (c == curr_callout && wakeup_needed) {
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/*
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* We're being asked to reschedule a callout which is
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* currently in progress, and someone has called
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* callout_drain to kill that callout. Don't reschedule.
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*/
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mtx_unlock_spin(&callout_lock);
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return;
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}
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if (c->c_flags & CALLOUT_PENDING) {
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if (nextsoftcheck == c) {
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nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
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}
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TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c,
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c_links.tqe);
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/*
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* Part of the normal "stop a pending callout" process
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* is to clear the CALLOUT_ACTIVE and CALLOUT_PENDING
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* flags. We're not going to bother doing that here,
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* because we're going to be setting those flags ten lines
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* after this point, and we're holding callout_lock
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* between now and then.
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*/
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}
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/*
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* We could unlock callout_lock here and lock it again before the
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* TAILQ_INSERT_TAIL, but there's no point since doing this setup
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* doesn't take much time.
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*/
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if (to_ticks <= 0)
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to_ticks = 1;
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c->c_arg = arg;
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c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING);
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c->c_func = ftn;
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c->c_time = ticks + to_ticks;
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TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask],
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c, c_links.tqe);
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mtx_unlock_spin(&callout_lock);
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}
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int
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_callout_stop_safe(c, safe)
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struct callout *c;
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int safe;
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{
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int wakeup_cookie;
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mtx_lock_spin(&callout_lock);
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/*
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* Don't attempt to delete a callout that's not on the queue.
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*/
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if (!(c->c_flags & CALLOUT_PENDING)) {
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c->c_flags &= ~CALLOUT_ACTIVE;
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if (c == curr_callout && safe) {
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/* We need to wait until the callout is finished. */
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wakeup_needed = 1;
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wakeup_cookie = wakeup_ctr++;
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mtx_unlock_spin(&callout_lock);
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mtx_lock(&callout_wait_lock);
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/*
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* Check to make sure that softclock() didn't
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* do the wakeup in between our dropping
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* callout_lock and picking up callout_wait_lock
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*/
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if (wakeup_cookie - wakeup_done_ctr > 0)
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cv_wait(&callout_wait, &callout_wait_lock);
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mtx_unlock(&callout_wait_lock);
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} else
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mtx_unlock_spin(&callout_lock);
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return (0);
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}
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c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
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if (nextsoftcheck == c) {
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nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
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}
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TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe);
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c->c_func = NULL;
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if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
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SLIST_INSERT_HEAD(&callfree, c, c_links.sle);
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}
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mtx_unlock_spin(&callout_lock);
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return (1);
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}
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void
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callout_init(c, mpsafe)
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struct callout *c;
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int mpsafe;
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{
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bzero(c, sizeof *c);
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if (mpsafe)
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c->c_flags |= CALLOUT_MPSAFE;
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}
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#ifdef APM_FIXUP_CALLTODO
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/*
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|
* Adjust the kernel calltodo timeout list. This routine is used after
|
|
* an APM resume to recalculate the calltodo timer list values with the
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|
* number of hz's we have been sleeping. The next hardclock() will detect
|
|
* that there are fired timers and run softclock() to execute them.
|
|
*
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|
* 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 independant on whether the suspend was 2 hours or
|
|
* 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu>
|
|
*/
|
|
void
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|
adjust_timeout_calltodo(time_change)
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|
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 = (time_change->tv_sec * 1000000 +
|
|
time_change->tv_usec + (tick - 1)) / tick + 1;
|
|
else if (time_change->tv_sec <= LONG_MAX / hz)
|
|
delta_ticks = time_change->tv_sec * hz +
|
|
(time_change->tv_usec + (tick - 1)) / 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() */
|
|
mtx_lock_spin(&callout_lock);
|
|
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;
|
|
}
|
|
mtx_unlock_spin(&callout_lock);
|
|
|
|
return;
|
|
}
|
|
#endif /* APM_FIXUP_CALLTODO */
|