/*- * 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. * * 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. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 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 * $FreeBSD$ */ #include #include #include #include #include #include /* * TODO: * allocate more timeout table slots when table overflows. */ /* Exported to machdep.c and/or kern_clock.c. */ struct callout *callout; struct callout_list callfree; int callwheelsize, callwheelbits, callwheelmask; struct callout_tailq *callwheel; int softticks; /* Like ticks, but for softclock(). */ struct mtx callout_lock; static struct callout *nextsoftcheck; /* Next callout to be checked. */ /* * 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 A. 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 *dummy) { register struct callout *c; register struct callout_tailq *bucket; register int curticks; register int steps; /* #steps since we last allowed interrupts */ #ifndef MAX_SOFTCLOCK_STEPS #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ #endif /* MAX_SOFTCLOCK_STEPS */ steps = 0; mtx_lock_spin(&callout_lock); while (softticks != ticks) { softticks++; /* * softticks may be modified by hard clock, so cache * it while we work on a given bucket. */ curticks = softticks; bucket = &callwheel[curticks & callwheelmask]; c = TAILQ_FIRST(bucket); while (c) { if (c->c_time != curticks) { c = TAILQ_NEXT(c, c_links.tqe); ++steps; if (steps >= MAX_SOFTCLOCK_STEPS) { nextsoftcheck = c; /* Give interrupts a chance. */ mtx_unlock_spin(&callout_lock); ; /* nothing */ mtx_lock_spin(&callout_lock); c = nextsoftcheck; steps = 0; } } else { void (*c_func)(void *); void *c_arg; int c_flags; nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); TAILQ_REMOVE(bucket, c, c_links.tqe); c_func = c->c_func; c_arg = c->c_arg; c_flags = c->c_flags; c->c_func = NULL; if (c->c_flags & CALLOUT_LOCAL_ALLOC) { c->c_flags = CALLOUT_LOCAL_ALLOC; SLIST_INSERT_HEAD(&callfree, c, c_links.sle); } else { c->c_flags = (c->c_flags & ~CALLOUT_PENDING); } mtx_unlock_spin(&callout_lock); if (!(c_flags & CALLOUT_MPSAFE)) mtx_lock(&Giant); c_func(c_arg); if (!(c_flags & CALLOUT_MPSAFE)) mtx_unlock(&Giant); mtx_lock_spin(&callout_lock); steps = 0; c = nextsoftcheck; } } } nextsoftcheck = NULL; mtx_unlock_spin(&callout_lock); } /* * 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(ftn, arg, to_ticks) timeout_t *ftn; void *arg; int to_ticks; { struct callout *new; struct callout_handle handle; mtx_lock_spin(&callout_lock); /* Fill in the next free callout structure. */ new = SLIST_FIRST(&callfree); if (new == NULL) /* XXX Attempt to malloc first */ panic("timeout table full"); SLIST_REMOVE_HEAD(&callfree, c_links.sle); callout_reset(new, to_ticks, ftn, arg); handle.callout = new; mtx_unlock_spin(&callout_lock); return (handle); } void untimeout(ftn, arg, handle) timeout_t *ftn; void *arg; struct callout_handle handle; { /* * Check for a handle that was initialized * by callout_handle_init, but never used * for a real timeout. */ if (handle.callout == NULL) return; mtx_lock_spin(&callout_lock); if (handle.callout->c_func == ftn && handle.callout->c_arg == arg) callout_stop(handle.callout); mtx_unlock_spin(&callout_lock); } void callout_handle_init(struct callout_handle *handle) { handle->callout = NULL; } /* * 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() * * defines three convenience macros: * * callout_active() - returns truth if callout has not been serviced * callout_pending() - returns truth if callout is still waiting for timeout * callout_deactivate() - marks the callout as having been serviced */ void callout_reset(c, to_ticks, ftn, arg) struct callout *c; int to_ticks; void (*ftn) __P((void *)); void *arg; { mtx_lock_spin(&callout_lock); if (c->c_flags & CALLOUT_PENDING) callout_stop(c); /* * We could unlock callout_lock here and lock it again before the * TAILQ_INSERT_TAIL, but there's no point since doing this setup * doesn't take much time. */ if (to_ticks <= 0) to_ticks = 1; c->c_arg = arg; c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); c->c_func = ftn; c->c_time = ticks + to_ticks; TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask], c, c_links.tqe); mtx_unlock_spin(&callout_lock); } void callout_stop(c) struct callout *c; { mtx_lock_spin(&callout_lock); /* * Don't attempt to delete a callout that's not on the queue. */ if (!(c->c_flags & CALLOUT_PENDING)) { c->c_flags &= ~CALLOUT_ACTIVE; mtx_unlock_spin(&callout_lock); return; } c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); if (nextsoftcheck == c) { nextsoftcheck = TAILQ_NEXT(c, c_links.tqe); } TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe); c->c_func = NULL; if (c->c_flags & CALLOUT_LOCAL_ALLOC) { SLIST_INSERT_HEAD(&callfree, c, c_links.sle); } mtx_unlock_spin(&callout_lock); } void callout_init(c, mpsafe) struct callout *c; int mpsafe; { bzero(c, sizeof *c); if (mpsafe) c->c_flags |= CALLOUT_MPSAFE; } #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 independant on whether the suspend was 2 hours or * 2 days. Your milage may vary. - Ken Key */ void adjust_timeout_calltodo(time_change) 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 */