#include /*- * 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 __FBSDID("$FreeBSD$"); #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef SMP #include #endif #ifdef __rtems__ int ncallout = 16; #endif /* __rtems__ */ SDT_PROVIDER_DEFINE(callout_execute); SDT_PROBE_DEFINE(callout_execute, kernel, , callout_start, callout-start); SDT_PROBE_ARGTYPE(callout_execute, kernel, , callout_start, 0, "struct callout *"); SDT_PROBE_DEFINE(callout_execute, kernel, , callout_end, 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; /* * The callout cpu migration entity represents informations necessary for * describing the migrating callout to the new callout cpu. * The cached informations are very important for deferring migration when * the migrating callout is already running. */ struct cc_mig_ent { #ifdef SMP void (*ce_migration_func)(void *); void *ce_migration_arg; int ce_migration_cpu; int ce_migration_ticks; #endif }; /* * 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 cc_mig_ent cc_migrating_entity; 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 #define cc_migration_func cc_migrating_entity.ce_migration_func #define cc_migration_arg cc_migrating_entity.ce_migration_arg #define cc_migration_cpu cc_migrating_entity.ce_migration_cpu #define cc_migration_ticks cc_migrating_entity.ce_migration_ticks struct callout_cpu cc_cpu[MAXCPU]; #define CPUBLOCK 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) #define CC_LOCK_ASSERT(cc) mtx_assert(&(cc)->cc_lock, MA_OWNED) 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. */ /* * Resets the migration entity tied to a specific callout cpu. */ static void cc_cme_cleanup(struct callout_cpu *cc) { #ifdef SMP cc->cc_migration_cpu = CPUBLOCK; cc->cc_migration_ticks = 0; cc->cc_migration_func = NULL; cc->cc_migration_arg = NULL; #endif } /* * Checks if migration is requested by a specific callout cpu. */ static int cc_cme_migrating(struct callout_cpu *cc) { #ifdef SMP return (cc->cc_migration_cpu != CPUBLOCK); #else return (0); #endif } /* * 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. */ #ifdef __rtems__ static void rtems_bsd_timeout_init(void *); static void rtems_bsd_callout_timer(rtems_id id, void *arg) { rtems_status_code sc; (void) arg; sc = rtems_timer_reset(id); BSD_ASSERT(sc == RTEMS_SUCCESSFUL); callout_tick(); } static void callout_cpu_init(struct callout_cpu *); SYSINIT(rtems_bsd_timeout, SI_SUB_VM, SI_ORDER_FIRST, rtems_bsd_timeout_init, NULL); static void rtems_bsd_timeout_init(void *unused) #else /* __rtems__ */ caddr_t kern_timeout_callwheel_alloc(caddr_t v) #endif /* __rtems__ */ { struct callout_cpu *cc; #ifdef __rtems__ rtems_status_code sc; rtems_id id; caddr_t v; (void) unused; #endif /* __rtems__ */ 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; #ifdef __rtems__ v = malloc(ncallout * sizeof(*cc->cc_callout) + callwheelsize * sizeof(*cc->cc_callwheel), M_CALLOUT, M_ZERO | M_WAITOK); #endif /* __rtems__ */ 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); #ifndef __rtems__ return(v); #else /* __rtems__ */ callout_cpu_init(cc); sc = rtems_timer_create(rtems_build_name('_', 'C', 'L', 'O'), &id); BSD_ASSERT(sc == RTEMS_SUCCESSFUL); sc = rtems_timer_server_fire_after(id, 1, rtems_bsd_callout_timer, NULL); BSD_ASSERT(sc == RTEMS_SUCCESSFUL); #endif /* __rtems__ */ } 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]); } cc_cme_cleanup(cc); 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); } } #ifdef SMP /* * Switches the cpu tied to a specific callout. * The function expects a locked incoming callout cpu and returns with * locked outcoming callout cpu. */ static struct callout_cpu * callout_cpu_switch(struct callout *c, struct callout_cpu *cc, int new_cpu) { struct callout_cpu *new_cc; MPASS(c != NULL && cc != NULL); CC_LOCK_ASSERT(cc); /* * Avoid interrupts and preemption firing after the callout cpu * is blocked in order to avoid deadlocks as the new thread * may be willing to acquire the callout cpu lock. */ c->c_cpu = CPUBLOCK; spinlock_enter(); CC_UNLOCK(cc); new_cc = CC_CPU(new_cpu); CC_LOCK(new_cc); spinlock_exit(); c->c_cpu = new_cpu; return (new_cc); } #endif #ifndef __rtems__ /* * 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)); } #endif /* __rtems__ */ /* * 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 CPU_FOREACH(cpu) { if (cpu == timeout_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; #ifdef SMP if (cpu == CPUBLOCK) { while (c->c_cpu == CPUBLOCK) cpu_spinwait(); continue; } #endif 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) { CC_LOCK_ASSERT(cc); if (to_ticks <= 0) to_ticks = 1; c->c_arg = arg; c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING); c->c_func = func; c->c_time = cc->cc_ticks + to_ticks; TAILQ_INSERT_TAIL(&cc->cc_callwheel[c->c_time & callwheelmask], c, c_links.tqe); } static void callout_cc_del(struct callout *c, struct callout_cpu *cc) { if (cc->cc_next == c) cc->cc_next = TAILQ_NEXT(c, c_links.tqe); if (c->c_flags & CALLOUT_LOCAL_ALLOC) { c->c_func = NULL; SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle); } } static struct callout * softclock_call_cc(struct callout *c, struct callout_cpu *cc, int *mpcalls, int *lockcalls, int *gcalls) { void (*c_func)(void *); void *c_arg; struct lock_class *class; struct lock_object *c_lock; int c_flags, sharedlock; #ifdef SMP struct callout_cpu *new_cc; void (*new_func)(void *); void *new_arg; int new_cpu, new_ticks; #endif #ifdef DIAGNOSTIC struct bintime bt1, bt2; struct timespec ts2; static uint64_t maxdt = 36893488147419102LL; /* 2 msec */ static timeout_t *lastfunc; #endif cc->cc_next = TAILQ_NEXT(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 &= ~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. * If the callout was scheduled for * migration just cancel it. */ if (cc_cme_migrating(cc)) cc_cme_cleanup(cc); cc->cc_waiting = 0; CC_UNLOCK(cc); wakeup(&cc->cc_waiting); CC_LOCK(cc); } else if (cc_cme_migrating(cc)) { #ifdef SMP /* * If the callout was scheduled for * migration just perform it now. */ new_cpu = cc->cc_migration_cpu; new_ticks = cc->cc_migration_ticks; new_func = cc->cc_migration_func; new_arg = cc->cc_migration_arg; cc_cme_cleanup(cc); /* * Handle deferred callout stops */ if ((c->c_flags & CALLOUT_DFRMIGRATION) == 0) { CTR3(KTR_CALLOUT, "deferred cancelled %p func %p arg %p", c, new_func, new_arg); callout_cc_del(c, cc); goto nextc; } c->c_flags &= ~CALLOUT_DFRMIGRATION; /* * It should be assert here that the * callout is not destroyed but that * is not easy. */ new_cc = callout_cpu_switch(c, cc, new_cpu); callout_cc_add(c, new_cc, new_ticks, new_func, new_arg, new_cpu); CC_UNLOCK(new_cc); CC_LOCK(cc); #else panic("migration should not happen"); #endif } #ifdef SMP nextc: #endif return (cc->cc_next); } /* * 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; #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 != NULL) { 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 { TAILQ_REMOVE(bucket, c, c_links.tqe); c = softclock_call_cc(c, cc, &mpcalls, &lockcalls, &gcalls); steps = 0; } } } 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() * * 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; 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); } #ifdef SMP /* * If the callout must migrate try to perform it immediately. * If the callout is currently running, just defer the migration * to a more appropriate moment. */ if (c->c_cpu != cpu) { if (cc->cc_curr == c) { cc->cc_migration_cpu = cpu; cc->cc_migration_ticks = to_ticks; cc->cc_migration_func = ftn; cc->cc_migration_arg = arg; c->c_flags |= CALLOUT_DFRMIGRATION; CTR5(KTR_CALLOUT, "migration of %p func %p arg %p in %d to %u deferred", c, c->c_func, c->c_arg, to_ticks, cpu); CC_UNLOCK(cc); return (cancelled); } cc = callout_cpu_switch(c, cc, cpu); } #endif callout_cc_add(c, cc, to_ticks, ftn, arg, cpu); 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, *old_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; old_cc = NULL; again: #endif /* __rtems__ */ cc = callout_lock(c); #ifndef __rtems__ /* * 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) { #ifdef SMP CC_UNLOCK(cc); sleepq_release(&old_cc->cc_waiting); sq_locked = 0; old_cc = NULL; goto again; #else panic("migration should not happen"); #endif } #endif /* __rtems__ */ /* * 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; 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->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; old_cc = NULL; /* Reacquire locks previously released. */ PICKUP_GIANT(); CC_LOCK(cc); #else /* __rtems__ */ /* * On RTEMS the LOR problem above does not * exist since here we do not use * sleepq_set_timeout() and instead use the * RTEMS watchdog. */ cc->cc_waiting = 1; msleep_spin(&cc->cc_waiting, &cc->cc_lock, "codrain", 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); KASSERT(!cc_cme_migrating(cc), ("callout wrongly scheduled for migration")); CC_UNLOCK(cc); KASSERT(!sq_locked, ("sleepqueue chain locked")); return (1); } else if ((c->c_flags & CALLOUT_DFRMIGRATION) != 0) { c->c_flags &= ~CALLOUT_DFRMIGRATION; CTR3(KTR_CALLOUT, "postponing stop %p func %p arg %p", c, c->c_func, c->c_arg); CC_UNLOCK(cc); 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); CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p", c, c->c_func, c->c_arg); TAILQ_REMOVE(&cc->cc_callwheel[c->c_time & callwheelmask], c, c_links.tqe); callout_cc_del(c, cc); 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 */ 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 */