/* $NetBSD: kern_timeout.c,v 1.47 2013/09/14 20:53:48 martin Exp $ */ /*- * Copyright (c) 2003, 2006, 2007, 2008, 2009 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe, and by Andrew Doran. * * 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. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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. */ /* * Copyright (c) 2001 Thomas Nordin * Copyright (c) 2000-2001 Artur Grabowski * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED ``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 AUTHOR 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. */ #include __KERNEL_RCSID(0, "$NetBSD: kern_timeout.c,v 1.47 2013/09/14 20:53:48 martin Exp $"); /* * Timeouts are kept in a hierarchical timing wheel. The c_time is the * value of c_cpu->cc_ticks when the timeout should be called. There are * four levels with 256 buckets each. See 'Scheme 7' in "Hashed and * Hierarchical Timing Wheels: Efficient Data Structures for Implementing * a Timer Facility" by George Varghese and Tony Lauck. * * Some of the "math" in here is a bit tricky. We have to beware of * wrapping ints. * * We use the fact that any element added to the queue must be added with * a positive time. That means that any element `to' on the queue cannot * be scheduled to timeout further in time than INT_MAX, but c->c_time can * be positive or negative so comparing it with anything is dangerous. * The only way we can use the c->c_time value in any predictable way is * when we calculate how far in the future `to' will timeout - "c->c_time * - c->c_cpu->cc_ticks". The result will always be positive for future * timeouts and 0 or negative for due timeouts. */ #define _CALLOUT_PRIVATE #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef DDB #include #include #include #include #include #endif #define BUCKETS 1024 #define WHEELSIZE 256 #define WHEELMASK 255 #define WHEELBITS 8 #define MASKWHEEL(wheel, time) (((time) >> ((wheel)*WHEELBITS)) & WHEELMASK) #define BUCKET(cc, rel, abs) \ (((rel) <= (1 << (2*WHEELBITS))) \ ? ((rel) <= (1 << WHEELBITS)) \ ? &(cc)->cc_wheel[MASKWHEEL(0, (abs))] \ : &(cc)->cc_wheel[MASKWHEEL(1, (abs)) + WHEELSIZE] \ : ((rel) <= (1 << (3*WHEELBITS))) \ ? &(cc)->cc_wheel[MASKWHEEL(2, (abs)) + 2*WHEELSIZE] \ : &(cc)->cc_wheel[MASKWHEEL(3, (abs)) + 3*WHEELSIZE]) #define MOVEBUCKET(cc, wheel, time) \ CIRCQ_APPEND(&(cc)->cc_todo, \ &(cc)->cc_wheel[MASKWHEEL((wheel), (time)) + (wheel)*WHEELSIZE]) /* * Circular queue definitions. */ #define CIRCQ_INIT(list) \ do { \ (list)->cq_next_l = (list); \ (list)->cq_prev_l = (list); \ } while (/*CONSTCOND*/0) #define CIRCQ_INSERT(elem, list) \ do { \ (elem)->cq_prev_e = (list)->cq_prev_e; \ (elem)->cq_next_l = (list); \ (list)->cq_prev_l->cq_next_l = (elem); \ (list)->cq_prev_l = (elem); \ } while (/*CONSTCOND*/0) #define CIRCQ_APPEND(fst, snd) \ do { \ if (!CIRCQ_EMPTY(snd)) { \ (fst)->cq_prev_l->cq_next_l = (snd)->cq_next_l; \ (snd)->cq_next_l->cq_prev_l = (fst)->cq_prev_l; \ (snd)->cq_prev_l->cq_next_l = (fst); \ (fst)->cq_prev_l = (snd)->cq_prev_l; \ CIRCQ_INIT(snd); \ } \ } while (/*CONSTCOND*/0) #define CIRCQ_REMOVE(elem) \ do { \ (elem)->cq_next_l->cq_prev_e = (elem)->cq_prev_e; \ (elem)->cq_prev_l->cq_next_e = (elem)->cq_next_e; \ } while (/*CONSTCOND*/0) #define CIRCQ_FIRST(list) ((list)->cq_next_e) #define CIRCQ_NEXT(elem) ((elem)->cq_next_e) #define CIRCQ_LAST(elem,list) ((elem)->cq_next_l == (list)) #define CIRCQ_EMPTY(list) ((list)->cq_next_l == (list)) static void callout_softclock(void *); struct callout_cpu { kmutex_t *cc_lock; sleepq_t cc_sleepq; u_int cc_nwait; u_int cc_ticks; lwp_t *cc_lwp; callout_impl_t *cc_active; callout_impl_t *cc_cancel; struct evcnt cc_ev_late; struct evcnt cc_ev_block; struct callout_circq cc_todo; /* Worklist */ struct callout_circq cc_wheel[BUCKETS]; /* Queues of timeouts */ char cc_name1[12]; char cc_name2[12]; }; static struct callout_cpu callout_cpu0; static void *callout_sih; static inline kmutex_t * callout_lock(callout_impl_t *c) { struct callout_cpu *cc; kmutex_t *lock; for (;;) { cc = c->c_cpu; lock = cc->cc_lock; mutex_spin_enter(lock); if (__predict_true(cc == c->c_cpu)) return lock; mutex_spin_exit(lock); } } /* * callout_startup: * * Initialize the callout facility, called at system startup time. * Do just enough to allow callouts to be safely registered. */ void callout_startup(void) { struct callout_cpu *cc; int b; KASSERT(curcpu()->ci_data.cpu_callout == NULL); cc = &callout_cpu0; cc->cc_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_SCHED); CIRCQ_INIT(&cc->cc_todo); for (b = 0; b < BUCKETS; b++) CIRCQ_INIT(&cc->cc_wheel[b]); curcpu()->ci_data.cpu_callout = cc; } /* * callout_init_cpu: * * Per-CPU initialization. */ CTASSERT(sizeof(callout_impl_t) <= sizeof(callout_t)); void callout_init_cpu(struct cpu_info *ci) { struct callout_cpu *cc; int b; if ((cc = ci->ci_data.cpu_callout) == NULL) { cc = kmem_zalloc(sizeof(*cc), KM_SLEEP); if (cc == NULL) panic("callout_init_cpu (1)"); cc->cc_lock = mutex_obj_alloc(MUTEX_DEFAULT, IPL_SCHED); CIRCQ_INIT(&cc->cc_todo); for (b = 0; b < BUCKETS; b++) CIRCQ_INIT(&cc->cc_wheel[b]); } else { /* Boot CPU, one time only. */ callout_sih = softint_establish(SOFTINT_CLOCK | SOFTINT_MPSAFE, callout_softclock, NULL); if (callout_sih == NULL) panic("callout_init_cpu (2)"); } sleepq_init(&cc->cc_sleepq); snprintf(cc->cc_name1, sizeof(cc->cc_name1), "late/%u", cpu_index(ci)); evcnt_attach_dynamic(&cc->cc_ev_late, EVCNT_TYPE_MISC, NULL, "callout", cc->cc_name1); snprintf(cc->cc_name2, sizeof(cc->cc_name2), "wait/%u", cpu_index(ci)); evcnt_attach_dynamic(&cc->cc_ev_block, EVCNT_TYPE_MISC, NULL, "callout", cc->cc_name2); ci->ci_data.cpu_callout = cc; } /* * callout_init: * * Initialize a callout structure. This must be quick, so we fill * only the minimum number of fields. */ void callout_init(callout_t *cs, u_int flags) { callout_impl_t *c = (callout_impl_t *)cs; struct callout_cpu *cc; KASSERT((flags & ~CALLOUT_FLAGMASK) == 0); cc = curcpu()->ci_data.cpu_callout; c->c_func = NULL; c->c_magic = CALLOUT_MAGIC; if (__predict_true((flags & CALLOUT_MPSAFE) != 0 && cc != NULL)) { c->c_flags = flags; c->c_cpu = cc; return; } c->c_flags = flags | CALLOUT_BOUND; c->c_cpu = &callout_cpu0; } /* * callout_destroy: * * Destroy a callout structure. The callout must be stopped. */ void callout_destroy(callout_t *cs) { callout_impl_t *c = (callout_impl_t *)cs; /* * It's not necessary to lock in order to see the correct value * of c->c_flags. If the callout could potentially have been * running, the current thread should have stopped it. */ KASSERT((c->c_flags & CALLOUT_PENDING) == 0); KASSERT(c->c_cpu->cc_lwp == curlwp || c->c_cpu->cc_active != c); KASSERTMSG(c->c_magic == CALLOUT_MAGIC, "callout %p: c_magic (%#x) != CALLOUT_MAGIC (%#x)", c, c->c_magic, CALLOUT_MAGIC); c->c_magic = 0; } /* * callout_schedule_locked: * * Schedule a callout to run. The function and argument must * already be set in the callout structure. Must be called with * callout_lock. */ static void callout_schedule_locked(callout_impl_t *c, kmutex_t *lock, int to_ticks) { struct callout_cpu *cc, *occ; int old_time; KASSERT(to_ticks >= 0); KASSERT(c->c_func != NULL); /* Initialize the time here, it won't change. */ occ = c->c_cpu; c->c_flags &= ~(CALLOUT_FIRED | CALLOUT_INVOKING); /* * If this timeout is already scheduled and now is moved * earlier, reschedule it now. Otherwise leave it in place * and let it be rescheduled later. */ if ((c->c_flags & CALLOUT_PENDING) != 0) { /* Leave on existing CPU. */ old_time = c->c_time; c->c_time = to_ticks + occ->cc_ticks; if (c->c_time - old_time < 0) { CIRCQ_REMOVE(&c->c_list); CIRCQ_INSERT(&c->c_list, &occ->cc_todo); } mutex_spin_exit(lock); return; } cc = curcpu()->ci_data.cpu_callout; if ((c->c_flags & CALLOUT_BOUND) != 0 || cc == occ || !mutex_tryenter(cc->cc_lock)) { /* Leave on existing CPU. */ c->c_time = to_ticks + occ->cc_ticks; c->c_flags |= CALLOUT_PENDING; CIRCQ_INSERT(&c->c_list, &occ->cc_todo); } else { /* Move to this CPU. */ c->c_cpu = cc; c->c_time = to_ticks + cc->cc_ticks; c->c_flags |= CALLOUT_PENDING; CIRCQ_INSERT(&c->c_list, &cc->cc_todo); mutex_spin_exit(cc->cc_lock); } mutex_spin_exit(lock); } /* * callout_reset: * * Reset a callout structure with a new function and argument, and * schedule it to run. */ void callout_reset(callout_t *cs, int to_ticks, void (*func)(void *), void *arg) { callout_impl_t *c = (callout_impl_t *)cs; kmutex_t *lock; KASSERT(c->c_magic == CALLOUT_MAGIC); KASSERT(func != NULL); lock = callout_lock(c); c->c_func = func; c->c_arg = arg; callout_schedule_locked(c, lock, to_ticks); } /* * callout_schedule: * * Schedule a callout to run. The function and argument must * already be set in the callout structure. */ void callout_schedule(callout_t *cs, int to_ticks) { callout_impl_t *c = (callout_impl_t *)cs; kmutex_t *lock; KASSERT(c->c_magic == CALLOUT_MAGIC); lock = callout_lock(c); callout_schedule_locked(c, lock, to_ticks); } /* * callout_stop: * * Try to cancel a pending callout. It may be too late: the callout * could be running on another CPU. If called from interrupt context, * the callout could already be in progress at a lower priority. */ bool callout_stop(callout_t *cs) { callout_impl_t *c = (callout_impl_t *)cs; struct callout_cpu *cc; kmutex_t *lock; bool expired; KASSERT(c->c_magic == CALLOUT_MAGIC); lock = callout_lock(c); if ((c->c_flags & CALLOUT_PENDING) != 0) CIRCQ_REMOVE(&c->c_list); expired = ((c->c_flags & CALLOUT_FIRED) != 0); c->c_flags &= ~(CALLOUT_PENDING|CALLOUT_FIRED); cc = c->c_cpu; if (cc->cc_active == c) { /* * This is for non-MPSAFE callouts only. To synchronize * effectively we must be called with kernel_lock held. * It's also taken in callout_softclock. */ cc->cc_cancel = c; } mutex_spin_exit(lock); return expired; } /* * callout_halt: * * Cancel a pending callout. If in-flight, block until it completes. * May not be called from a hard interrupt handler. If the callout * can take locks, the caller of callout_halt() must not hold any of * those locks, otherwise the two could deadlock. If 'interlock' is * non-NULL and we must wait for the callout to complete, it will be * released and re-acquired before returning. */ bool callout_halt(callout_t *cs, void *interlock) { callout_impl_t *c = (callout_impl_t *)cs; struct callout_cpu *cc; struct lwp *l; kmutex_t *lock, *relock; bool expired; KASSERT(c->c_magic == CALLOUT_MAGIC); KASSERT(!cpu_intr_p()); lock = callout_lock(c); relock = NULL; expired = ((c->c_flags & CALLOUT_FIRED) != 0); if ((c->c_flags & CALLOUT_PENDING) != 0) CIRCQ_REMOVE(&c->c_list); c->c_flags &= ~(CALLOUT_PENDING|CALLOUT_FIRED); l = curlwp; for (;;) { cc = c->c_cpu; if (__predict_true(cc->cc_active != c || cc->cc_lwp == l)) break; if (interlock != NULL) { /* * Avoid potential scheduler lock order problems by * dropping the interlock without the callout lock * held. */ mutex_spin_exit(lock); mutex_exit(interlock); relock = interlock; interlock = NULL; } else { /* XXX Better to do priority inheritance. */ KASSERT(l->l_wchan == NULL); cc->cc_nwait++; cc->cc_ev_block.ev_count++; l->l_kpriority = true; sleepq_enter(&cc->cc_sleepq, l, cc->cc_lock); sleepq_enqueue(&cc->cc_sleepq, cc, "callout", &sleep_syncobj); sleepq_block(0, false); } lock = callout_lock(c); } mutex_spin_exit(lock); if (__predict_false(relock != NULL)) mutex_enter(relock); return expired; } #ifdef notyet /* * callout_bind: * * Bind a callout so that it will only execute on one CPU. * The callout must be stopped, and must be MPSAFE. * * XXX Disabled for now until it is decided how to handle * offlined CPUs. We may want weak+strong binding. */ void callout_bind(callout_t *cs, struct cpu_info *ci) { callout_impl_t *c = (callout_impl_t *)cs; struct callout_cpu *cc; kmutex_t *lock; KASSERT((c->c_flags & CALLOUT_PENDING) == 0); KASSERT(c->c_cpu->cc_active != c); KASSERT(c->c_magic == CALLOUT_MAGIC); KASSERT((c->c_flags & CALLOUT_MPSAFE) != 0); lock = callout_lock(c); cc = ci->ci_data.cpu_callout; c->c_flags |= CALLOUT_BOUND; if (c->c_cpu != cc) { /* * Assigning c_cpu effectively unlocks the callout * structure, as we don't hold the new CPU's lock. * Issue memory barrier to prevent accesses being * reordered. */ membar_exit(); c->c_cpu = cc; } mutex_spin_exit(lock); } #endif void callout_setfunc(callout_t *cs, void (*func)(void *), void *arg) { callout_impl_t *c = (callout_impl_t *)cs; kmutex_t *lock; KASSERT(c->c_magic == CALLOUT_MAGIC); KASSERT(func != NULL); lock = callout_lock(c); c->c_func = func; c->c_arg = arg; mutex_spin_exit(lock); } bool callout_expired(callout_t *cs) { callout_impl_t *c = (callout_impl_t *)cs; kmutex_t *lock; bool rv; KASSERT(c->c_magic == CALLOUT_MAGIC); lock = callout_lock(c); rv = ((c->c_flags & CALLOUT_FIRED) != 0); mutex_spin_exit(lock); return rv; } bool callout_active(callout_t *cs) { callout_impl_t *c = (callout_impl_t *)cs; kmutex_t *lock; bool rv; KASSERT(c->c_magic == CALLOUT_MAGIC); lock = callout_lock(c); rv = ((c->c_flags & (CALLOUT_PENDING|CALLOUT_FIRED)) != 0); mutex_spin_exit(lock); return rv; } bool callout_pending(callout_t *cs) { callout_impl_t *c = (callout_impl_t *)cs; kmutex_t *lock; bool rv; KASSERT(c->c_magic == CALLOUT_MAGIC); lock = callout_lock(c); rv = ((c->c_flags & CALLOUT_PENDING) != 0); mutex_spin_exit(lock); return rv; } bool callout_invoking(callout_t *cs) { callout_impl_t *c = (callout_impl_t *)cs; kmutex_t *lock; bool rv; KASSERT(c->c_magic == CALLOUT_MAGIC); lock = callout_lock(c); rv = ((c->c_flags & CALLOUT_INVOKING) != 0); mutex_spin_exit(lock); return rv; } void callout_ack(callout_t *cs) { callout_impl_t *c = (callout_impl_t *)cs; kmutex_t *lock; KASSERT(c->c_magic == CALLOUT_MAGIC); lock = callout_lock(c); c->c_flags &= ~CALLOUT_INVOKING; mutex_spin_exit(lock); } /* * callout_hardclock: * * Called from hardclock() once every tick. We schedule a soft * interrupt if there is work to be done. */ void callout_hardclock(void) { struct callout_cpu *cc; int needsoftclock, ticks; cc = curcpu()->ci_data.cpu_callout; mutex_spin_enter(cc->cc_lock); ticks = ++cc->cc_ticks; MOVEBUCKET(cc, 0, ticks); if (MASKWHEEL(0, ticks) == 0) { MOVEBUCKET(cc, 1, ticks); if (MASKWHEEL(1, ticks) == 0) { MOVEBUCKET(cc, 2, ticks); if (MASKWHEEL(2, ticks) == 0) MOVEBUCKET(cc, 3, ticks); } } needsoftclock = !CIRCQ_EMPTY(&cc->cc_todo); mutex_spin_exit(cc->cc_lock); if (needsoftclock) softint_schedule(callout_sih); } /* * callout_softclock: * * Soft interrupt handler, scheduled above if there is work to * be done. Callouts are made in soft interrupt context. */ static void callout_softclock(void *v) { callout_impl_t *c; struct callout_cpu *cc; void (*func)(void *); void *arg; int mpsafe, count, ticks, delta; lwp_t *l; l = curlwp; KASSERT(l->l_cpu == curcpu()); cc = l->l_cpu->ci_data.cpu_callout; mutex_spin_enter(cc->cc_lock); cc->cc_lwp = l; while (!CIRCQ_EMPTY(&cc->cc_todo)) { c = CIRCQ_FIRST(&cc->cc_todo); KASSERT(c->c_magic == CALLOUT_MAGIC); KASSERT(c->c_func != NULL); KASSERT(c->c_cpu == cc); KASSERT((c->c_flags & CALLOUT_PENDING) != 0); KASSERT((c->c_flags & CALLOUT_FIRED) == 0); CIRCQ_REMOVE(&c->c_list); /* If due run it, otherwise insert it into the right bucket. */ ticks = cc->cc_ticks; delta = c->c_time - ticks; if (delta > 0) { CIRCQ_INSERT(&c->c_list, BUCKET(cc, delta, c->c_time)); continue; } if (delta < 0) cc->cc_ev_late.ev_count++; c->c_flags = (c->c_flags & ~CALLOUT_PENDING) | (CALLOUT_FIRED | CALLOUT_INVOKING); mpsafe = (c->c_flags & CALLOUT_MPSAFE); func = c->c_func; arg = c->c_arg; cc->cc_active = c; mutex_spin_exit(cc->cc_lock); KASSERT(func != NULL); if (__predict_false(!mpsafe)) { KERNEL_LOCK(1, NULL); (*func)(arg); KERNEL_UNLOCK_ONE(NULL); } else (*func)(arg); mutex_spin_enter(cc->cc_lock); /* * We can't touch 'c' here because it might be * freed already. If LWPs waiting for callout * to complete, awaken them. */ cc->cc_active = NULL; if ((count = cc->cc_nwait) != 0) { cc->cc_nwait = 0; /* sleepq_wake() drops the lock. */ sleepq_wake(&cc->cc_sleepq, cc, count, cc->cc_lock); mutex_spin_enter(cc->cc_lock); } } cc->cc_lwp = NULL; mutex_spin_exit(cc->cc_lock); } #ifdef DDB static void db_show_callout_bucket(struct callout_cpu *cc, struct callout_circq *bucket) { callout_impl_t *c; db_expr_t offset; const char *name; static char question[] = "?"; int b; if (CIRCQ_EMPTY(bucket)) return; for (c = CIRCQ_FIRST(bucket); /*nothing*/; c = CIRCQ_NEXT(&c->c_list)) { db_find_sym_and_offset((db_addr_t)(intptr_t)c->c_func, &name, &offset); name = name ? name : question; b = (bucket - cc->cc_wheel); if (b < 0) b = -WHEELSIZE; db_printf("%9d %2d/%-4d %16lx %s\n", c->c_time - cc->cc_ticks, b / WHEELSIZE, b, (u_long)c->c_arg, name); if (CIRCQ_LAST(&c->c_list, bucket)) break; } } void db_show_callout(db_expr_t addr, bool haddr, db_expr_t count, const char *modif) { CPU_INFO_ITERATOR cii; struct callout_cpu *cc; struct cpu_info *ci; int b; db_printf("hardclock_ticks now: %d\n", hardclock_ticks); db_printf(" ticks wheel arg func\n"); /* * Don't lock the callwheel; all the other CPUs are paused * anyhow, and we might be called in a circumstance where * some other CPU was paused while holding the lock. */ for (CPU_INFO_FOREACH(cii, ci)) { cc = ci->ci_data.cpu_callout; db_show_callout_bucket(cc, &cc->cc_todo); } for (b = 0; b < BUCKETS; b++) { for (CPU_INFO_FOREACH(cii, ci)) { cc = ci->ci_data.cpu_callout; db_show_callout_bucket(cc, &cc->cc_wheel[b]); } } } #endif /* DDB */