86fd19de7b
callout_stop, callout_drain, and callout_deactivate, but is not automatically cleared when a callout returns.
567 lines
16 KiB
C
567 lines
16 KiB
C
/*-
|
|
* 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 <sys/param.h>
|
|
#include <sys/systm.h>
|
|
#include <sys/callout.h>
|
|
#include <sys/condvar.h>
|
|
#include <sys/kernel.h>
|
|
#include <sys/ktr.h>
|
|
#include <sys/lock.h>
|
|
#include <sys/mutex.h>
|
|
#include <sys/sysctl.h>
|
|
|
|
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_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.
|
|
*/
|
|
|
|
/* Exported to machdep.c and/or kern_clock.c. */
|
|
struct callout *callout;
|
|
struct callout_list callfree;
|
|
int callwheelsize, callwheelbits, callwheelmask;
|
|
struct callout_tailq *callwheel;
|
|
int softticks; /* Like ticks, but for softclock(). */
|
|
struct mtx callout_lock;
|
|
#ifdef DIAGNOSTIC
|
|
struct mtx dont_sleep_in_callout;
|
|
#endif
|
|
|
|
static struct callout *nextsoftcheck; /* Next callout to be checked. */
|
|
|
|
/**
|
|
* Locked by callout_lock:
|
|
* curr_callout - If a callout is in progress, it is curr_callout.
|
|
* If curr_callout is non-NULL, threads waiting on
|
|
* callout_wait will be woken up as soon as the
|
|
* relevant callout completes.
|
|
* wakeup_ctr - Incremented every time a thread wants to wait
|
|
* for a callout to complete. Modified only when
|
|
* curr_callout is non-NULL.
|
|
* wakeup_needed - If a thread is waiting on callout_wait, then
|
|
* wakeup_needed is nonzero. Increased only when
|
|
* cutt_callout is non-NULL.
|
|
*/
|
|
static struct callout *curr_callout;
|
|
static int wakeup_ctr;
|
|
static int wakeup_needed;
|
|
|
|
/**
|
|
* Locked by callout_wait_lock:
|
|
* callout_wait - If wakeup_needed is set, callout_wait will be
|
|
* triggered after the current callout finishes.
|
|
* wakeup_done_ctr - Set to the current value of wakeup_ctr after
|
|
* callout_wait is triggered.
|
|
*/
|
|
static struct mtx callout_wait_lock;
|
|
static struct cv callout_wait;
|
|
static int wakeup_done_ctr;
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
/*
|
|
* Calculate callout wheel size
|
|
*/
|
|
for (callwheelsize = 1, callwheelbits = 0;
|
|
callwheelsize < ncallout;
|
|
callwheelsize <<= 1, ++callwheelbits)
|
|
;
|
|
callwheelmask = callwheelsize - 1;
|
|
|
|
callout = (struct callout *)v;
|
|
v = (caddr_t)(callout + ncallout);
|
|
callwheel = (struct callout_tailq *)v;
|
|
v = (caddr_t)(callwheel + callwheelsize);
|
|
return(v);
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
int i;
|
|
|
|
SLIST_INIT(&callfree);
|
|
for (i = 0; i < ncallout; i++) {
|
|
callout_init(&callout[i], 0);
|
|
callout[i].c_flags = CALLOUT_LOCAL_ALLOC;
|
|
SLIST_INSERT_HEAD(&callfree, &callout[i], c_links.sle);
|
|
}
|
|
for (i = 0; i < callwheelsize; i++) {
|
|
TAILQ_INIT(&callwheel[i]);
|
|
}
|
|
mtx_init(&callout_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE);
|
|
#ifdef DIAGNOSTIC
|
|
mtx_init(&dont_sleep_in_callout, "dont_sleep_in_callout", NULL, MTX_DEF);
|
|
#endif
|
|
mtx_init(&callout_wait_lock, "callout_wait_lock", NULL, MTX_DEF);
|
|
cv_init(&callout_wait, "callout_wait");
|
|
}
|
|
|
|
/*
|
|
* 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 *dummy)
|
|
{
|
|
struct callout *c;
|
|
struct callout_tailq *bucket;
|
|
int curticks;
|
|
int steps; /* #steps since we last allowed interrupts */
|
|
int depth;
|
|
int mpcalls;
|
|
int gcalls;
|
|
int wakeup_cookie;
|
|
#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;
|
|
gcalls = 0;
|
|
depth = 0;
|
|
steps = 0;
|
|
mtx_lock_spin(&callout_lock);
|
|
while (softticks != ticks) {
|
|
softticks++;
|
|
/*
|
|
* softticks may be modified by hard clock, so cache
|
|
* it while we work on a given bucket.
|
|
*/
|
|
curticks = softticks;
|
|
bucket = &callwheel[curticks & callwheelmask];
|
|
c = TAILQ_FIRST(bucket);
|
|
while (c) {
|
|
depth++;
|
|
if (c->c_time != curticks) {
|
|
c = TAILQ_NEXT(c, c_links.tqe);
|
|
++steps;
|
|
if (steps >= MAX_SOFTCLOCK_STEPS) {
|
|
nextsoftcheck = c;
|
|
/* Give interrupts a chance. */
|
|
mtx_unlock_spin(&callout_lock);
|
|
; /* nothing */
|
|
mtx_lock_spin(&callout_lock);
|
|
c = nextsoftcheck;
|
|
steps = 0;
|
|
}
|
|
} else {
|
|
void (*c_func)(void *);
|
|
void *c_arg;
|
|
int c_flags;
|
|
|
|
nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
|
|
TAILQ_REMOVE(bucket, c, c_links.tqe);
|
|
c_func = c->c_func;
|
|
c_arg = c->c_arg;
|
|
c_flags = c->c_flags;
|
|
c->c_func = NULL;
|
|
if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
|
|
c->c_flags = CALLOUT_LOCAL_ALLOC;
|
|
SLIST_INSERT_HEAD(&callfree, c,
|
|
c_links.sle);
|
|
} else {
|
|
c->c_flags =
|
|
(c->c_flags & ~CALLOUT_PENDING);
|
|
}
|
|
curr_callout = c;
|
|
mtx_unlock_spin(&callout_lock);
|
|
if (!(c_flags & CALLOUT_MPSAFE)) {
|
|
mtx_lock(&Giant);
|
|
gcalls++;
|
|
CTR1(KTR_CALLOUT, "callout %p", c_func);
|
|
} else {
|
|
mpcalls++;
|
|
CTR1(KTR_CALLOUT, "callout mpsafe %p",
|
|
c_func);
|
|
}
|
|
#ifdef DIAGNOSTIC
|
|
binuptime(&bt1);
|
|
mtx_lock(&dont_sleep_in_callout);
|
|
#endif
|
|
c_func(c_arg);
|
|
#ifdef DIAGNOSTIC
|
|
mtx_unlock(&dont_sleep_in_callout);
|
|
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
|
|
if (!(c_flags & CALLOUT_MPSAFE))
|
|
mtx_unlock(&Giant);
|
|
mtx_lock_spin(&callout_lock);
|
|
curr_callout = NULL;
|
|
if (wakeup_needed) {
|
|
/*
|
|
* There might be someone waiting
|
|
* for the callout to complete.
|
|
*/
|
|
wakeup_cookie = wakeup_ctr;
|
|
mtx_unlock_spin(&callout_lock);
|
|
mtx_lock(&callout_wait_lock);
|
|
cv_broadcast(&callout_wait);
|
|
wakeup_done_ctr = wakeup_cookie;
|
|
mtx_unlock(&callout_wait_lock);
|
|
mtx_lock_spin(&callout_lock);
|
|
wakeup_needed = 0;
|
|
}
|
|
steps = 0;
|
|
c = nextsoftcheck;
|
|
}
|
|
}
|
|
}
|
|
avg_depth += (depth * 1000 - avg_depth) >> 8;
|
|
avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8;
|
|
avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8;
|
|
nextsoftcheck = NULL;
|
|
mtx_unlock_spin(&callout_lock);
|
|
}
|
|
|
|
/*
|
|
* timeout --
|
|
* Execute a function after a specified length of time.
|
|
*
|
|
* untimeout --
|
|
* Cancel previous timeout function call.
|
|
*
|
|
* callout_handle_init --
|
|
* Initialize a handle so that using it with untimeout is benign.
|
|
*
|
|
* See AT&T BCI Driver Reference Manual for specification. This
|
|
* implementation differs from that one in that although an
|
|
* identification value is returned from timeout, the original
|
|
* arguments to timeout as well as the identifier are used to
|
|
* identify entries for untimeout.
|
|
*/
|
|
struct callout_handle
|
|
timeout(ftn, arg, to_ticks)
|
|
timeout_t *ftn;
|
|
void *arg;
|
|
int to_ticks;
|
|
{
|
|
struct callout *new;
|
|
struct callout_handle handle;
|
|
|
|
mtx_lock_spin(&callout_lock);
|
|
|
|
/* Fill in the next free callout structure. */
|
|
new = SLIST_FIRST(&callfree);
|
|
if (new == NULL)
|
|
/* XXX Attempt to malloc first */
|
|
panic("timeout table full");
|
|
SLIST_REMOVE_HEAD(&callfree, c_links.sle);
|
|
|
|
callout_reset(new, to_ticks, ftn, arg);
|
|
|
|
handle.callout = new;
|
|
mtx_unlock_spin(&callout_lock);
|
|
return (handle);
|
|
}
|
|
|
|
void
|
|
untimeout(ftn, arg, handle)
|
|
timeout_t *ftn;
|
|
void *arg;
|
|
struct callout_handle handle;
|
|
{
|
|
|
|
/*
|
|
* Check for a handle that was initialized
|
|
* by callout_handle_init, but never used
|
|
* for a real timeout.
|
|
*/
|
|
if (handle.callout == NULL)
|
|
return;
|
|
|
|
mtx_lock_spin(&callout_lock);
|
|
if (handle.callout->c_func == ftn && handle.callout->c_arg == arg)
|
|
callout_stop(handle.callout);
|
|
mtx_unlock_spin(&callout_lock);
|
|
}
|
|
|
|
void
|
|
callout_handle_init(struct callout_handle *handle)
|
|
{
|
|
handle->callout = NULL;
|
|
}
|
|
|
|
/*
|
|
* New interface; clients allocate their own callout structures.
|
|
*
|
|
* callout_reset() - establish or change a timeout
|
|
* callout_stop() - disestablish a timeout
|
|
* callout_init() - initialize a callout structure so that it can
|
|
* safely be passed to callout_reset() and callout_stop()
|
|
*
|
|
* <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
|
|
*/
|
|
void
|
|
callout_reset(c, to_ticks, ftn, arg)
|
|
struct callout *c;
|
|
int to_ticks;
|
|
void (*ftn)(void *);
|
|
void *arg;
|
|
{
|
|
|
|
mtx_lock_spin(&callout_lock);
|
|
if (c == curr_callout && wakeup_needed) {
|
|
/*
|
|
* We're being asked to reschedule a callout which is
|
|
* currently in progress, and someone has called
|
|
* callout_drain to kill that callout. Don't reschedule.
|
|
*/
|
|
mtx_unlock_spin(&callout_lock);
|
|
return;
|
|
}
|
|
if (c->c_flags & CALLOUT_PENDING) {
|
|
if (nextsoftcheck == c) {
|
|
nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
|
|
}
|
|
TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c,
|
|
c_links.tqe);
|
|
|
|
/*
|
|
* Part of the normal "stop a pending callout" process
|
|
* is to clear the CALLOUT_ACTIVE and CALLOUT_PENDING
|
|
* flags. We're not going to bother doing that here,
|
|
* because we're going to be setting those flags ten lines
|
|
* after this point, and we're holding callout_lock
|
|
* between now and then.
|
|
*/
|
|
}
|
|
|
|
/*
|
|
* We could unlock callout_lock here and lock it again before the
|
|
* TAILQ_INSERT_TAIL, but there's no point since doing this setup
|
|
* doesn't take much time.
|
|
*/
|
|
if (to_ticks <= 0)
|
|
to_ticks = 1;
|
|
|
|
c->c_arg = arg;
|
|
c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING);
|
|
c->c_func = ftn;
|
|
c->c_time = ticks + to_ticks;
|
|
TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask],
|
|
c, c_links.tqe);
|
|
mtx_unlock_spin(&callout_lock);
|
|
}
|
|
|
|
int
|
|
_callout_stop_safe(c, safe)
|
|
struct callout *c;
|
|
int safe;
|
|
{
|
|
int wakeup_cookie;
|
|
|
|
mtx_lock_spin(&callout_lock);
|
|
/*
|
|
* Don't attempt to delete a callout that's not on the queue.
|
|
*/
|
|
if (!(c->c_flags & CALLOUT_PENDING)) {
|
|
c->c_flags &= ~CALLOUT_ACTIVE;
|
|
if (c == curr_callout && safe) {
|
|
/* We need to wait until the callout is finished. */
|
|
wakeup_needed = 1;
|
|
wakeup_cookie = wakeup_ctr++;
|
|
mtx_unlock_spin(&callout_lock);
|
|
mtx_lock(&callout_wait_lock);
|
|
|
|
/*
|
|
* Check to make sure that softclock() didn't
|
|
* do the wakeup in between our dropping
|
|
* callout_lock and picking up callout_wait_lock
|
|
*/
|
|
if (wakeup_cookie - wakeup_done_ctr > 0)
|
|
cv_wait(&callout_wait, &callout_wait_lock);
|
|
|
|
mtx_unlock(&callout_wait_lock);
|
|
} else
|
|
mtx_unlock_spin(&callout_lock);
|
|
return (0);
|
|
}
|
|
c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
|
|
|
|
if (nextsoftcheck == c) {
|
|
nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
|
|
}
|
|
TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe);
|
|
c->c_func = NULL;
|
|
|
|
if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
|
|
SLIST_INSERT_HEAD(&callfree, c, c_links.sle);
|
|
}
|
|
mtx_unlock_spin(&callout_lock);
|
|
return (1);
|
|
}
|
|
|
|
void
|
|
callout_init(c, mpsafe)
|
|
struct callout *c;
|
|
int mpsafe;
|
|
{
|
|
bzero(c, sizeof *c);
|
|
if (mpsafe)
|
|
c->c_flags |= CALLOUT_MPSAFE;
|
|
}
|
|
|
|
#ifdef APM_FIXUP_CALLTODO
|
|
/*
|
|
* Adjust the kernel calltodo timeout list. This routine is used after
|
|
* an APM resume to recalculate the calltodo timer list values with the
|
|
* number of hz's we have been sleeping. The next hardclock() will detect
|
|
* that there are fired timers and run softclock() to execute them.
|
|
*
|
|
* Please note, I have not done an exhaustive analysis of what code this
|
|
* might break. I am motivated to have my select()'s and alarm()'s that
|
|
* have expired during suspend firing upon resume so that the applications
|
|
* which set the timer can do the maintanence the timer was for as close
|
|
* as possible to the originally intended time. Testing this code for a
|
|
* week showed that resuming from a suspend resulted in 22 to 25 timers
|
|
* firing, which seemed independant on whether the suspend was 2 hours or
|
|
* 2 days. Your milage may vary. - Ken Key <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() */
|
|
mtx_lock_spin(&callout_lock);
|
|
for (p = calltodo.c_next; p != NULL; p = p->c_next) {
|
|
p->c_time -= delta_ticks;
|
|
|
|
/* Break if the timer had more time on it than delta_ticks */
|
|
if (p->c_time > 0)
|
|
break;
|
|
|
|
/* take back the ticks the timer didn't use (p->c_time <= 0) */
|
|
delta_ticks = -p->c_time;
|
|
}
|
|
mtx_unlock_spin(&callout_lock);
|
|
|
|
return;
|
|
}
|
|
#endif /* APM_FIXUP_CALLTODO */
|