diff options
Diffstat (limited to 'freebsd/kern/kern_timeout.c')
| -rw-r--r-- | freebsd/kern/kern_timeout.c | 927 |
1 files changed, 927 insertions, 0 deletions
diff --git a/freebsd/kern/kern_timeout.c b/freebsd/kern/kern_timeout.c new file mode 100644 index 00000000..536ca3f3 --- /dev/null +++ b/freebsd/kern/kern_timeout.c @@ -0,0 +1,927 @@ +#include <freebsd/machine/rtems-bsd-config.h> + +/*- + * 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. + * 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 + */ + +#include <freebsd/sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <freebsd/local/opt_kdtrace.h> + +#include <freebsd/sys/param.h> +#include <freebsd/sys/systm.h> +#include <freebsd/sys/bus.h> +#include <freebsd/sys/callout.h> +#include <freebsd/sys/condvar.h> +#include <freebsd/sys/interrupt.h> +#include <freebsd/sys/kernel.h> +#include <freebsd/sys/ktr.h> +#include <freebsd/sys/lock.h> +#include <freebsd/sys/malloc.h> +#include <freebsd/sys/mutex.h> +#include <freebsd/sys/proc.h> +#include <freebsd/sys/sdt.h> +#include <freebsd/sys/sleepqueue.h> +#include <freebsd/sys/sysctl.h> +#include <freebsd/sys/smp.h> + +#ifdef __rtems__ +int ncallout = 16; +#endif /* __rtems__ */ +SDT_PROVIDER_DEFINE(callout_execute); +SDT_PROBE_DEFINE(callout_execute, kernel, , callout_start); +SDT_PROBE_ARGTYPE(callout_execute, kernel, , callout_start, 0, + "struct callout *"); +SDT_PROBE_DEFINE(callout_execute, kernel, , callout_end); +SDT_PROBE_ARGTYPE(callout_execute, kernel, , callout_end, 0, + "struct callout *"); + +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"); +/* + * TODO: + * allocate more timeout table slots when table overflows. + */ +int callwheelsize, callwheelbits, callwheelmask; + +/* + * There is one struct callout_cpu per cpu, holding all relevant + * state for the callout processing thread on the individual CPU. + * In particular: + * cc_ticks is incremented once per tick in callout_cpu(). + * It tracks the global 'ticks' but in a way that the individual + * threads should not worry about races in the order in which + * hardclock() and hardclock_cpu() run on the various CPUs. + * cc_softclock is advanced in callout_cpu() to point to the + * first entry in cc_callwheel that may need handling. In turn, + * a softclock() is scheduled so it can serve the various entries i + * such that cc_softclock <= i <= cc_ticks . + * XXX maybe cc_softclock and cc_ticks should be volatile ? + * + * cc_ticks is also used in callout_reset_cpu() to determine + * when the callout should be served. + */ +struct callout_cpu { + struct mtx cc_lock; + struct callout *cc_callout; + struct callout_tailq *cc_callwheel; + struct callout_list cc_callfree; + struct callout *cc_next; + struct callout *cc_curr; + void *cc_cookie; + int cc_ticks; + int cc_softticks; + int cc_cancel; + int cc_waiting; +}; + +#ifdef SMP +struct callout_cpu cc_cpu[MAXCPU]; +#define CC_CPU(cpu) (&cc_cpu[(cpu)]) +#define CC_SELF() CC_CPU(PCPU_GET(cpuid)) +#else +struct callout_cpu cc_cpu; +#define CC_CPU(cpu) &cc_cpu +#define CC_SELF() &cc_cpu +#endif +#define CC_LOCK(cc) mtx_lock_spin(&(cc)->cc_lock) +#define CC_UNLOCK(cc) mtx_unlock_spin(&(cc)->cc_lock) + +static int timeout_cpu; + +MALLOC_DEFINE(M_CALLOUT, "callout", "Callout datastructures"); + +/** + * Locked by cc_lock: + * cc_curr - If a callout is in progress, it is curr_callout. + * If curr_callout 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 c_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 + * c_lock is successfully acquired. + * cc_waiting - If a thread is waiting in callout_drain(), then + * callout_wait is nonzero. Set only when + * curr_callout is non-NULL. + */ + +/* + * kern_timeout_callwheel_alloc() - kernel low level callwheel initialization + * + * This code is called very early in the kernel initialization sequence, + * and may be called more then once. + */ +caddr_t +kern_timeout_callwheel_alloc(caddr_t v) +{ + struct callout_cpu *cc; + + timeout_cpu = PCPU_GET(cpuid); + cc = CC_CPU(timeout_cpu); + /* + * Calculate callout wheel size + */ + for (callwheelsize = 1, callwheelbits = 0; + callwheelsize < ncallout; + callwheelsize <<= 1, ++callwheelbits) + ; + callwheelmask = callwheelsize - 1; + + cc->cc_callout = (struct callout *)v; + v = (caddr_t)(cc->cc_callout + ncallout); + cc->cc_callwheel = (struct callout_tailq *)v; + v = (caddr_t)(cc->cc_callwheel + callwheelsize); + return(v); +} + +static void +callout_cpu_init(struct callout_cpu *cc) +{ + struct callout *c; + int i; + + mtx_init(&cc->cc_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE); + SLIST_INIT(&cc->cc_callfree); + for (i = 0; i < callwheelsize; i++) { + TAILQ_INIT(&cc->cc_callwheel[i]); + } + if (cc->cc_callout == NULL) + return; + for (i = 0; i < ncallout; i++) { + c = &cc->cc_callout[i]; + callout_init(c, 0); + c->c_flags = CALLOUT_LOCAL_ALLOC; + SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); + } +} + +/* + * kern_timeout_callwheel_init() - initialize previously reserved callwheel + * space. + * + * This code is called just once, after the space reserved for the + * callout wheel has been finalized. + */ +void +kern_timeout_callwheel_init(void) +{ + callout_cpu_init(CC_CPU(timeout_cpu)); +} + +/* + * Start standard softclock thread. + */ +void *softclock_ih; + +static void +start_softclock(void *dummy) +{ + struct callout_cpu *cc; +#ifdef SMP + int cpu; +#endif + + cc = CC_CPU(timeout_cpu); + if (swi_add(&clk_intr_event, "clock", softclock, cc, SWI_CLOCK, + INTR_MPSAFE, &softclock_ih)) + panic("died while creating standard software ithreads"); + cc->cc_cookie = softclock_ih; +#ifdef SMP + for (cpu = 0; cpu <= mp_maxid; cpu++) { + if (cpu == timeout_cpu) + continue; + if (CPU_ABSENT(cpu)) + continue; + cc = CC_CPU(cpu); + if (swi_add(NULL, "clock", softclock, cc, SWI_CLOCK, + INTR_MPSAFE, &cc->cc_cookie)) + panic("died while creating standard software ithreads"); + cc->cc_callout = NULL; /* Only cpu0 handles timeout(). */ + cc->cc_callwheel = malloc( + sizeof(struct callout_tailq) * callwheelsize, M_CALLOUT, + M_WAITOK); + callout_cpu_init(cc); + } +#endif +} + +SYSINIT(start_softclock, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softclock, NULL); + +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_spin_flags(&cc->cc_lock, MTX_QUIET); + cc->cc_ticks++; + for (; (cc->cc_softticks - cc->cc_ticks) <= 0; cc->cc_softticks++) { + bucket = cc->cc_softticks & callwheelmask; + if (!TAILQ_EMPTY(&cc->cc_callwheel[bucket])) { + need_softclock = 1; + break; + } + } + mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET); + /* + * swi_sched acquires the thread lock, so we don't want to call it + * with cc_lock held; incorrect locking order. + */ + if (need_softclock) + swi_sched(cc->cc_cookie, 0); +} + +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); +} + +/* + * 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_cpu *cc; + struct callout *c; + struct callout_tailq *bucket; + int curticks; + int steps; /* #steps since we last allowed interrupts */ + int depth; + int mpcalls; + int lockcalls; + int gcalls; +#ifdef DIAGNOSTIC + struct bintime bt1, bt2; + struct timespec ts2; + static uint64_t maxdt = 36893488147419102LL; /* 2 msec */ + static timeout_t *lastfunc; +#endif + +#ifndef MAX_SOFTCLOCK_STEPS +#define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */ +#endif /* MAX_SOFTCLOCK_STEPS */ + + mpcalls = 0; + lockcalls = 0; + gcalls = 0; + depth = 0; + steps = 0; + cc = (struct callout_cpu *)arg; + CC_LOCK(cc); + while (cc->cc_softticks - 1 != cc->cc_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++; + bucket = &cc->cc_callwheel[curticks & callwheelmask]; + c = TAILQ_FIRST(bucket); + while (c) { + depth++; + if (c->c_time != curticks) { + c = TAILQ_NEXT(c, c_links.tqe); + ++steps; + if (steps >= MAX_SOFTCLOCK_STEPS) { + cc->cc_next = c; + /* Give interrupts a chance. */ + CC_UNLOCK(cc); + ; /* nothing */ + CC_LOCK(cc); + c = cc->cc_next; + steps = 0; + } + } else { + void (*c_func)(void *); + void *c_arg; + struct lock_class *class; + struct lock_object *c_lock; + int c_flags, sharedlock; + + cc->cc_next = TAILQ_NEXT(c, c_links.tqe); + TAILQ_REMOVE(bucket, c, c_links.tqe); + class = (c->c_lock != NULL) ? + LOCK_CLASS(c->c_lock) : NULL; + sharedlock = (c->c_flags & CALLOUT_SHAREDLOCK) ? + 0 : 1; + c_lock = c->c_lock; + c_func = c->c_func; + c_arg = c->c_arg; + c_flags = c->c_flags; + if (c->c_flags & CALLOUT_LOCAL_ALLOC) { + c->c_flags = CALLOUT_LOCAL_ALLOC; + } else { + c->c_flags = + (c->c_flags & ~CALLOUT_PENDING); + } + cc->cc_curr = c; + cc->cc_cancel = 0; + CC_UNLOCK(cc); + if (c_lock != NULL) { + class->lc_lock(c_lock, sharedlock); + /* + * The callout may have been cancelled + * while we switched locks. + */ + if (cc->cc_cancel) { + class->lc_unlock(c_lock); + goto skip; + } + /* The callout cannot be stopped now. */ + cc->cc_cancel = 1; + + if (c_lock == &Giant.lock_object) { + gcalls++; + CTR3(KTR_CALLOUT, + "callout %p func %p arg %p", + c, c_func, c_arg); + } else { + lockcalls++; + CTR3(KTR_CALLOUT, "callout lock" + " %p func %p arg %p", + c, c_func, c_arg); + } + } else { + mpcalls++; + CTR3(KTR_CALLOUT, + "callout mpsafe %p func %p arg %p", + c, c_func, c_arg); + } +#ifdef DIAGNOSTIC + binuptime(&bt1); +#endif +#ifndef __rtems__ + THREAD_NO_SLEEPING(); + SDT_PROBE(callout_execute, kernel, , + callout_start, c, 0, 0, 0, 0); +#endif /* __rtems__ */ + c_func(c_arg); +#ifndef __rtems__ + SDT_PROBE(callout_execute, kernel, , + callout_end, c, 0, 0, 0, 0); + THREAD_SLEEPING_OK(); +#endif /* __rtems__ */ +#ifdef DIAGNOSTIC + binuptime(&bt2); + bintime_sub(&bt2, &bt1); + if (bt2.frac > maxdt) { + if (lastfunc != c_func || + bt2.frac > maxdt * 2) { + bintime2timespec(&bt2, &ts2); + printf( + "Expensive timeout(9) function: %p(%p) %jd.%09ld s\n", + c_func, c_arg, + (intmax_t)ts2.tv_sec, + ts2.tv_nsec); + } + maxdt = bt2.frac; + lastfunc = c_func; + } +#endif + CTR1(KTR_CALLOUT, "callout %p finished", c); + if ((c_flags & CALLOUT_RETURNUNLOCKED) == 0) + class->lc_unlock(c_lock); + skip: + CC_LOCK(cc); + /* + * 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_flags because if it was not + * local, then it's not safe to deref the + * callout pointer. + */ + if (c_flags & CALLOUT_LOCAL_ALLOC) { + KASSERT(c->c_flags == + CALLOUT_LOCAL_ALLOC, + ("corrupted callout")); + c->c_func = NULL; + SLIST_INSERT_HEAD(&cc->cc_callfree, c, + c_links.sle); + } + cc->cc_curr = NULL; + if (cc->cc_waiting) { + /* + * There is someone waiting + * for the callout to complete. + */ + cc->cc_waiting = 0; + CC_UNLOCK(cc); + wakeup(&cc->cc_waiting); + CC_LOCK(cc); + } + steps = 0; + c = cc->cc_next; + } + } + } + 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; + cc->cc_next = NULL; + CC_UNLOCK(cc); +} + +/* + * 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_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(ftn, arg, handle) + 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; +} + +/* + * 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_on(struct callout *c, int to_ticks, void (*ftn)(void *), + void *arg, int cpu) +{ + struct callout_cpu *cc; + int cancelled = 0; + + /* + * Don't allow migration of pre-allocated callouts lest they + * become unbalanced. + */ + if (c->c_flags & CALLOUT_LOCAL_ALLOC) + cpu = c->c_cpu; +retry: + cc = callout_lock(c); + if (cc->cc_curr == 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->cc_cancel) + cancelled = cc->cc_cancel = 1; + if (cc->cc_waiting) { + /* + * 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_flags & CALLOUT_PENDING) { + if (cc->cc_next == c) { + cc->cc_next = TAILQ_NEXT(c, c_links.tqe); + } + TAILQ_REMOVE(&cc->cc_callwheel[c->c_time & callwheelmask], c, + c_links.tqe); + + cancelled = 1; + c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); + } + /* + * If the lock must migrate we have to check the state again as + * we can't hold both the new and old locks simultaneously. + */ + if (c->c_cpu != cpu) { + c->c_cpu = cpu; + CC_UNLOCK(cc); + goto retry; + } + + 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 = cc->cc_ticks + to_ticks; + TAILQ_INSERT_TAIL(&cc->cc_callwheel[c->c_time & callwheelmask], + c, c_links.tqe); + 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(c, safe) + struct callout *c; + int safe; +{ + struct callout_cpu *cc; + struct lock_class *class; +#ifndef __rtems__ + int use_lock, sq_locked; +#else /* __rtems__ */ + int use_lock; +#endif /* __rtems__ */ + + /* + * Some old subsystems don't hold Giant while running a callout_stop(), + * so just discard this check for the moment. + */ + if (!safe && 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; + +#ifndef __rtems__ + sq_locked = 0; +again: +#endif /* __rtems__ */ + cc = callout_lock(c); + /* + * If the callout isn't pending, it's not on the queue, so + * don't attempt to remove it from the queue. We can try to + * stop it by other means however. + */ + if (!(c->c_flags & CALLOUT_PENDING)) { + c->c_flags &= ~CALLOUT_ACTIVE; + + /* + * If it wasn't on the queue and it isn't the current + * callout, then we can't stop it, so just bail. + */ + if (cc->cc_curr != c) { + CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", + c, c->c_func, c->c_arg); + CC_UNLOCK(cc); +#ifndef __rtems__ + if (sq_locked) + sleepq_release(&cc->cc_waiting); +#endif /* __rtems__ */ + return (0); + } + + if (safe) { + /* + * 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->cc_curr == c) { +#ifndef __rtems__ + + /* + * 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->cc_waiting); + sq_locked = 1; + goto again; + } + cc->cc_waiting = 1; + DROP_GIANT(); + CC_UNLOCK(cc); + sleepq_add(&cc->cc_waiting, + &cc->cc_lock.lock_object, "codrain", + SLEEPQ_SLEEP, 0); + sleepq_wait(&cc->cc_waiting, 0); + sq_locked = 0; + + /* Reacquire locks previously released. */ + PICKUP_GIANT(); + CC_LOCK(cc); +#else /* __rtems__ */ + BSD_ASSERT(0); +#endif /* __rtems__ */ + } + } else if (use_lock && !cc->cc_cancel) { + /* + * 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(). + */ + cc->cc_cancel = 1; + CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", + c, c->c_func, c->c_arg); + CC_UNLOCK(cc); + KASSERT(!sq_locked, ("sleepqueue chain locked")); + return (1); + } + CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p", + c, c->c_func, c->c_arg); + CC_UNLOCK(cc); + KASSERT(!sq_locked, ("sleepqueue chain still locked")); + return (0); + } +#ifndef __rtems__ + if (sq_locked) + sleepq_release(&cc->cc_waiting); +#endif /* __rtems__ */ + + c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING); + + if (cc->cc_next == c) { + cc->cc_next = TAILQ_NEXT(c, c_links.tqe); + } + TAILQ_REMOVE(&cc->cc_callwheel[c->c_time & callwheelmask], c, + c_links.tqe); + + CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", + c, c->c_func, c->c_arg); + + if (c->c_flags & CALLOUT_LOCAL_ALLOC) { + c->c_func = NULL; + SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); + } + CC_UNLOCK(cc); + return (1); +} + +void +callout_init(c, mpsafe) + struct callout *c; + int mpsafe; +{ + bzero(c, sizeof *c); + if (mpsafe) { + c->c_lock = NULL; + c->c_flags = CALLOUT_RETURNUNLOCKED; + } else { + c->c_lock = &Giant.lock_object; + c->c_flags = 0; + } + c->c_cpu = timeout_cpu; +} + +void +_callout_init_lock(c, lock, flags) + 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_flags = 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 independant on whether the suspend was 2 hours or + * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu> + */ +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() */ + 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 */ |