/*-
* 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_kdtrace.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/callout.h>
#include <sys/condvar.h>
#include <sys/interrupt.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sdt.h>
#include <sys/sleepqueue.h>
#include <sys/sysctl.h>
#include <sys/smp.h>
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;
/*
* 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;
int cc_firsttick;
};
#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;
void (*callout_new_inserted)(int cpu, int ticks) = NULL;
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
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_firsttick = cc->cc_ticks = 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);
}
int
callout_tickstofirst(int limit)
{
struct callout_cpu *cc;
struct callout *c;
struct callout_tailq *sc;
int curticks;
int skip = 1;
cc = CC_SELF();
mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET);
curticks = cc->cc_ticks;
while( skip < ncallout && skip < limit ) {
sc = &cc->cc_callwheel[ (curticks+skip) & callwheelmask ];
/* search scanning ticks */
TAILQ_FOREACH( c, sc, c_links.tqe ){
if (c && (c->c_time <= curticks + ncallout)
&& (c->c_time > 0))
goto out;
}
skip++;
}
out:
cc->cc_firsttick = curticks + skip;
mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET);
return (skip);
}
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
THREAD_NO_SLEEPING();
SDT_PROBE(callout_execute, kernel, ,
callout_start, c, 0, 0, 0, 0);
c_func(c_arg);
SDT_PROBE(callout_execute, kernel, ,
callout_end, c, 0, 0, 0, 0);
THREAD_SLEEPING_OK();
#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 = ticks + to_ticks;
TAILQ_INSERT_TAIL(&cc->cc_callwheel[c->c_time & callwheelmask],
c, c_links.tqe);
if ((c->c_time - cc->cc_firsttick) < 0 &&
callout_new_inserted != NULL) {
cc->cc_firsttick = c->c_time;
(*callout_new_inserted)(cpu,
to_ticks + (ticks - cc->cc_ticks));
}
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;
int use_lock, sq_locked;
/*
* 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;
sq_locked = 0;
again:
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);
if (sq_locked)
sleepq_release(&cc->cc_waiting);
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) {
/*
* 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 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);
}
if (sq_locked)
sleepq_release(&cc->cc_waiting);
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 */
