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freebsd-dev/sys/kern/kern_timeout.c
Eric van Gyzen 8c5a9161d1 Save the last callout function executed on each CPU 
Save the last callout function pointer (and its argument) executed
on each CPU for inspection by a debugger.  Add a ddb `show callout_last`
command to show these pointers.  Add a kernel module that I used
for testing that command.

Relocate `ce_migration_cpu` to reduce padding and therefore preserve
the size of `struct callout_cpu` (320 bytes on amd64) despite the
added members.

This should help diagnose reference-after-free bugs where the
callout's mutex has already been freed when `softclock_call_cc`
tries to unlock it.

You might hope that the pointer would still be available, but it
isn't.  The argument to that function is on the stack (because
`softclock_call_cc` uses it later), and that might be enough in
some cases, but even then, it's very laborious.  A pointer to the
callout is saved right before these newly added fields, but that
callout might have been freed.  We still have the pointer to its
associated mutex, and the name within might be enough, but it might
also have been freed.

Reviewed by:	markj jhb
MFC after:	2 weeks
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D20794
2019-07-03 19:22:44 +00:00

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/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* 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.
* 3. 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_callout_profiling.h"
#include "opt_ddb.h"
#if defined(__arm__)
#include "opt_timer.h"
#endif
#include "opt_rss.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/callout.h>
#include <sys/file.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>
#ifdef DDB
#include <ddb/ddb.h>
#include <ddb/db_sym.h>
#include <machine/_inttypes.h>
#endif
#ifdef SMP
#include <machine/cpu.h>
#endif
#ifndef NO_EVENTTIMERS
DPCPU_DECLARE(sbintime_t, hardclocktime);
#endif
SDT_PROVIDER_DEFINE(callout_execute);
SDT_PROBE_DEFINE1(callout_execute, , , callout__start, "struct callout *");
SDT_PROBE_DEFINE1(callout_execute, , , callout__end, "struct callout *");
#ifdef CALLOUT_PROFILING
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");
static int avg_depth_dir;
SYSCTL_INT(_debug, OID_AUTO, to_avg_depth_dir, CTLFLAG_RD, &avg_depth_dir, 0,
"Average number of direct callouts examined per callout_process call. "
"Units = 1/1000");
static int avg_lockcalls_dir;
SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls_dir, CTLFLAG_RD,
&avg_lockcalls_dir, 0, "Average number of lock direct callouts made per "
"callout_process call. Units = 1/1000");
static int avg_mpcalls_dir;
SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls_dir, CTLFLAG_RD, &avg_mpcalls_dir,
0, "Average number of MP direct callouts made per callout_process call. "
"Units = 1/1000");
#endif
static int ncallout;
SYSCTL_INT(_kern, OID_AUTO, ncallout, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &ncallout, 0,
"Number of entries in callwheel and size of timeout() preallocation");
#ifdef RSS
static int pin_default_swi = 1;
static int pin_pcpu_swi = 1;
#else
static int pin_default_swi = 0;
static int pin_pcpu_swi = 0;
#endif
SYSCTL_INT(_kern, OID_AUTO, pin_default_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &pin_default_swi,
0, "Pin the default (non-per-cpu) swi (shared with PCPU 0 swi)");
SYSCTL_INT(_kern, OID_AUTO, pin_pcpu_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &pin_pcpu_swi,
0, "Pin the per-CPU swis (except PCPU 0, which is also default");
/*
* TODO:
* allocate more timeout table slots when table overflows.
*/
u_int callwheelsize, callwheelmask;
/*
* The callout cpu exec entities represent informations necessary for
* describing the state of callouts currently running on the CPU and the ones
* necessary for migrating callouts to the new callout cpu. In particular,
* the first entry of the array cc_exec_entity holds informations for callout
* running in SWI thread context, while the second one holds informations
* for callout running directly from hardware interrupt context.
* The cached informations are very important for deferring migration when
* the migrating callout is already running.
*/
struct cc_exec {
struct callout *cc_curr;
void (*cc_drain)(void *);
void *cc_last_func;
void *cc_last_arg;
#ifdef SMP
void (*ce_migration_func)(void *);
void *ce_migration_arg;
sbintime_t ce_migration_time;
sbintime_t ce_migration_prec;
int ce_migration_cpu;
#endif
bool cc_cancel;
bool cc_waiting;
};
/*
* There is one struct callout_cpu per cpu, holding all relevant
* state for the callout processing thread on the individual CPU.
*/
struct callout_cpu {
struct mtx_padalign cc_lock;
struct cc_exec cc_exec_entity[2];
struct callout *cc_next;
struct callout *cc_callout;
struct callout_list *cc_callwheel;
struct callout_tailq cc_expireq;
struct callout_slist cc_callfree;
sbintime_t cc_firstevent;
sbintime_t cc_lastscan;
void *cc_cookie;
u_int cc_bucket;
u_int cc_inited;
char cc_ktr_event_name[20];
};
#define callout_migrating(c) ((c)->c_iflags & CALLOUT_DFRMIGRATION)
#define cc_exec_curr(cc, dir) cc->cc_exec_entity[dir].cc_curr
#define cc_exec_last_func(cc, dir) cc->cc_exec_entity[dir].cc_last_func
#define cc_exec_last_arg(cc, dir) cc->cc_exec_entity[dir].cc_last_arg
#define cc_exec_drain(cc, dir) cc->cc_exec_entity[dir].cc_drain
#define cc_exec_next(cc) cc->cc_next
#define cc_exec_cancel(cc, dir) cc->cc_exec_entity[dir].cc_cancel
#define cc_exec_waiting(cc, dir) cc->cc_exec_entity[dir].cc_waiting
#ifdef SMP
#define cc_migration_func(cc, dir) cc->cc_exec_entity[dir].ce_migration_func
#define cc_migration_arg(cc, dir) cc->cc_exec_entity[dir].ce_migration_arg
#define cc_migration_cpu(cc, dir) cc->cc_exec_entity[dir].ce_migration_cpu
#define cc_migration_time(cc, dir) cc->cc_exec_entity[dir].ce_migration_time
#define cc_migration_prec(cc, dir) cc->cc_exec_entity[dir].ce_migration_prec
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;
static void callout_cpu_init(struct callout_cpu *cc, int cpu);
static void softclock_call_cc(struct callout *c, struct callout_cpu *cc,
#ifdef CALLOUT_PROFILING
int *mpcalls, int *lockcalls, int *gcalls,
#endif
int direct);
static MALLOC_DEFINE(M_CALLOUT, "callout", "Callout datastructures");
/**
* Locked by cc_lock:
* cc_curr - If a callout is in progress, it is cc_curr.
* If cc_curr 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 cc_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
* cc_lock is successfully acquired.
* cc_waiting - If a thread is waiting in callout_drain(), then
* callout_wait is nonzero. Set only when
* cc_curr is non-NULL.
*/
/*
* Resets the execution entity tied to a specific callout cpu.
*/
static void
cc_cce_cleanup(struct callout_cpu *cc, int direct)
{
cc_exec_curr(cc, direct) = NULL;
cc_exec_cancel(cc, direct) = false;
cc_exec_waiting(cc, direct) = false;
#ifdef SMP
cc_migration_cpu(cc, direct) = CPUBLOCK;
cc_migration_time(cc, direct) = 0;
cc_migration_prec(cc, direct) = 0;
cc_migration_func(cc, direct) = NULL;
cc_migration_arg(cc, direct) = NULL;
#endif
}
/*
* Checks if migration is requested by a specific callout cpu.
*/
static int
cc_cce_migrating(struct callout_cpu *cc, int direct)
{
#ifdef SMP
return (cc_migration_cpu(cc, direct) != CPUBLOCK);
#else
return (0);
#endif
}
/*
* Kernel low level callwheel initialization
* called on the BSP during kernel startup.
*/
static void
callout_callwheel_init(void *dummy)
{
struct callout_cpu *cc;
/*
* Calculate the size of the callout wheel and the preallocated
* timeout() structures.
* XXX: Clip callout to result of previous function of maxusers
* maximum 384. This is still huge, but acceptable.
*/
memset(CC_CPU(curcpu), 0, sizeof(cc_cpu));
ncallout = imin(16 + maxproc + maxfiles, 18508);
TUNABLE_INT_FETCH("kern.ncallout", &ncallout);
/*
* Calculate callout wheel size, should be next power of two higher
* than 'ncallout'.
*/
callwheelsize = 1 << fls(ncallout);
callwheelmask = callwheelsize - 1;
/*
* Fetch whether we're pinning the swi's or not.
*/
TUNABLE_INT_FETCH("kern.pin_default_swi", &pin_default_swi);
TUNABLE_INT_FETCH("kern.pin_pcpu_swi", &pin_pcpu_swi);
/*
* Only BSP handles timeout(9) and receives a preallocation.
*
* XXX: Once all timeout(9) consumers are converted this can
* be removed.
*/
timeout_cpu = PCPU_GET(cpuid);
cc = CC_CPU(timeout_cpu);
cc->cc_callout = malloc(ncallout * sizeof(struct callout),
M_CALLOUT, M_WAITOK);
callout_cpu_init(cc, timeout_cpu);
}
SYSINIT(callwheel_init, SI_SUB_CPU, SI_ORDER_ANY, callout_callwheel_init, NULL);
/*
* Initialize the per-cpu callout structures.
*/
static void
callout_cpu_init(struct callout_cpu *cc, int cpu)
{
struct callout *c;
int i;
mtx_init(&cc->cc_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE);
SLIST_INIT(&cc->cc_callfree);
cc->cc_inited = 1;
cc->cc_callwheel = malloc(sizeof(struct callout_list) * callwheelsize,
M_CALLOUT, M_WAITOK);
for (i = 0; i < callwheelsize; i++)
LIST_INIT(&cc->cc_callwheel[i]);
TAILQ_INIT(&cc->cc_expireq);
cc->cc_firstevent = SBT_MAX;
for (i = 0; i < 2; i++)
cc_cce_cleanup(cc, i);
snprintf(cc->cc_ktr_event_name, sizeof(cc->cc_ktr_event_name),
"callwheel cpu %d", cpu);
if (cc->cc_callout == NULL) /* Only BSP handles timeout(9) */
return;
for (i = 0; i < ncallout; i++) {
c = &cc->cc_callout[i];
callout_init(c, 0);
c->c_iflags = 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
/*
* Start standard softclock thread.
*/
static void
start_softclock(void *dummy)
{
struct callout_cpu *cc;
char name[MAXCOMLEN];
#ifdef SMP
int cpu;
struct intr_event *ie;
#endif
cc = CC_CPU(timeout_cpu);
snprintf(name, sizeof(name), "clock (%d)", timeout_cpu);
if (swi_add(&clk_intr_event, name, softclock, cc, SWI_CLOCK,
INTR_MPSAFE, &cc->cc_cookie))
panic("died while creating standard software ithreads");
if (pin_default_swi &&
(intr_event_bind(clk_intr_event, timeout_cpu) != 0)) {
printf("%s: timeout clock couldn't be pinned to cpu %d\n",
__func__,
timeout_cpu);
}
#ifdef SMP
CPU_FOREACH(cpu) {
if (cpu == timeout_cpu)
continue;
cc = CC_CPU(cpu);
cc->cc_callout = NULL; /* Only BSP handles timeout(9). */
callout_cpu_init(cc, cpu);
snprintf(name, sizeof(name), "clock (%d)", cpu);
ie = NULL;
if (swi_add(&ie, name, softclock, cc, SWI_CLOCK,
INTR_MPSAFE, &cc->cc_cookie))
panic("died while creating standard software ithreads");
if (pin_pcpu_swi && (intr_event_bind(ie, cpu) != 0)) {
printf("%s: per-cpu clock couldn't be pinned to "
"cpu %d\n",
__func__,
cpu);
}
}
#endif
}
SYSINIT(start_softclock, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softclock, NULL);
#define CC_HASH_SHIFT 8
static inline u_int
callout_hash(sbintime_t sbt)
{
return (sbt >> (32 - CC_HASH_SHIFT));
}
static inline u_int
callout_get_bucket(sbintime_t sbt)
{
return (callout_hash(sbt) & callwheelmask);
}
void
callout_process(sbintime_t now)
{
struct callout *tmp, *tmpn;
struct callout_cpu *cc;
struct callout_list *sc;
sbintime_t first, last, max, tmp_max;
uint32_t lookahead;
u_int firstb, lastb, nowb;
#ifdef CALLOUT_PROFILING
int depth_dir = 0, mpcalls_dir = 0, lockcalls_dir = 0;
#endif
cc = CC_SELF();
mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET);
/* Compute the buckets of the last scan and present times. */
firstb = callout_hash(cc->cc_lastscan);
cc->cc_lastscan = now;
nowb = callout_hash(now);
/* Compute the last bucket and minimum time of the bucket after it. */
if (nowb == firstb)
lookahead = (SBT_1S / 16);
else if (nowb - firstb == 1)
lookahead = (SBT_1S / 8);
else
lookahead = (SBT_1S / 2);
first = last = now;
first += (lookahead / 2);
last += lookahead;
last &= (0xffffffffffffffffLLU << (32 - CC_HASH_SHIFT));
lastb = callout_hash(last) - 1;
max = last;
/*
* Check if we wrapped around the entire wheel from the last scan.
* In case, we need to scan entirely the wheel for pending callouts.
*/
if (lastb - firstb >= callwheelsize) {
lastb = firstb + callwheelsize - 1;
if (nowb - firstb >= callwheelsize)
nowb = lastb;
}
/* Iterate callwheel from firstb to nowb and then up to lastb. */
do {
sc = &cc->cc_callwheel[firstb & callwheelmask];
tmp = LIST_FIRST(sc);
while (tmp != NULL) {
/* Run the callout if present time within allowed. */
if (tmp->c_time <= now) {
/*
* Consumer told us the callout may be run
* directly from hardware interrupt context.
*/
if (tmp->c_iflags & CALLOUT_DIRECT) {
#ifdef CALLOUT_PROFILING
++depth_dir;
#endif
cc_exec_next(cc) =
LIST_NEXT(tmp, c_links.le);
cc->cc_bucket = firstb & callwheelmask;
LIST_REMOVE(tmp, c_links.le);
softclock_call_cc(tmp, cc,
#ifdef CALLOUT_PROFILING
&mpcalls_dir, &lockcalls_dir, NULL,
#endif
1);
tmp = cc_exec_next(cc);
cc_exec_next(cc) = NULL;
} else {
tmpn = LIST_NEXT(tmp, c_links.le);
LIST_REMOVE(tmp, c_links.le);
TAILQ_INSERT_TAIL(&cc->cc_expireq,
tmp, c_links.tqe);
tmp->c_iflags |= CALLOUT_PROCESSED;
tmp = tmpn;
}
continue;
}
/* Skip events from distant future. */
if (tmp->c_time >= max)
goto next;
/*
* Event minimal time is bigger than present maximal
* time, so it cannot be aggregated.
*/
if (tmp->c_time > last) {
lastb = nowb;
goto next;
}
/* Update first and last time, respecting this event. */
if (tmp->c_time < first)
first = tmp->c_time;
tmp_max = tmp->c_time + tmp->c_precision;
if (tmp_max < last)
last = tmp_max;
next:
tmp = LIST_NEXT(tmp, c_links.le);
}
/* Proceed with the next bucket. */
firstb++;
/*
* Stop if we looked after present time and found
* some event we can't execute at now.
* Stop if we looked far enough into the future.
*/
} while (((int)(firstb - lastb)) <= 0);
cc->cc_firstevent = last;
#ifndef NO_EVENTTIMERS
cpu_new_callout(curcpu, last, first);
#endif
#ifdef CALLOUT_PROFILING
avg_depth_dir += (depth_dir * 1000 - avg_depth_dir) >> 8;
avg_mpcalls_dir += (mpcalls_dir * 1000 - avg_mpcalls_dir) >> 8;
avg_lockcalls_dir += (lockcalls_dir * 1000 - avg_lockcalls_dir) >> 8;
#endif
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 (!TAILQ_EMPTY(&cc->cc_expireq))
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,
sbintime_t sbt, sbintime_t precision, void (*func)(void *),
void *arg, int cpu, int flags)
{
int bucket;
CC_LOCK_ASSERT(cc);
if (sbt < cc->cc_lastscan)
sbt = cc->cc_lastscan;
c->c_arg = arg;
c->c_iflags |= CALLOUT_PENDING;
c->c_iflags &= ~CALLOUT_PROCESSED;
c->c_flags |= CALLOUT_ACTIVE;
if (flags & C_DIRECT_EXEC)
c->c_iflags |= CALLOUT_DIRECT;
c->c_func = func;
c->c_time = sbt;
c->c_precision = precision;
bucket = callout_get_bucket(c->c_time);
CTR3(KTR_CALLOUT, "precision set for %p: %d.%08x",
c, (int)(c->c_precision >> 32),
(u_int)(c->c_precision & 0xffffffff));
LIST_INSERT_HEAD(&cc->cc_callwheel[bucket], c, c_links.le);
if (cc->cc_bucket == bucket)
cc_exec_next(cc) = c;
#ifndef NO_EVENTTIMERS
/*
* Inform the eventtimers(4) subsystem there's a new callout
* that has been inserted, but only if really required.
*/
if (SBT_MAX - c->c_time < c->c_precision)
c->c_precision = SBT_MAX - c->c_time;
sbt = c->c_time + c->c_precision;
if (sbt < cc->cc_firstevent) {
cc->cc_firstevent = sbt;
cpu_new_callout(cpu, sbt, c->c_time);
}
#endif
}
static void
callout_cc_del(struct callout *c, struct callout_cpu *cc)
{
if ((c->c_iflags & CALLOUT_LOCAL_ALLOC) == 0)
return;
c->c_func = NULL;
SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle);
}
static void
softclock_call_cc(struct callout *c, struct callout_cpu *cc,
#ifdef CALLOUT_PROFILING
int *mpcalls, int *lockcalls, int *gcalls,
#endif
int direct)
{
struct rm_priotracker tracker;
void (*c_func)(void *);
void *c_arg;
struct lock_class *class;
struct lock_object *c_lock;
uintptr_t lock_status;
int c_iflags;
#ifdef SMP
struct callout_cpu *new_cc;
void (*new_func)(void *);
void *new_arg;
int flags, new_cpu;
sbintime_t new_prec, new_time;
#endif
#if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING)
sbintime_t sbt1, sbt2;
struct timespec ts2;
static sbintime_t maxdt = 2 * SBT_1MS; /* 2 msec */
static timeout_t *lastfunc;
#endif
KASSERT((c->c_iflags & CALLOUT_PENDING) == CALLOUT_PENDING,
("softclock_call_cc: pend %p %x", c, c->c_iflags));
KASSERT((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE,
("softclock_call_cc: act %p %x", c, c->c_flags));
class = (c->c_lock != NULL) ? LOCK_CLASS(c->c_lock) : NULL;
lock_status = 0;
if (c->c_flags & CALLOUT_SHAREDLOCK) {
if (class == &lock_class_rm)
lock_status = (uintptr_t)&tracker;
else
lock_status = 1;
}
c_lock = c->c_lock;
c_func = c->c_func;
c_arg = c->c_arg;
c_iflags = c->c_iflags;
if (c->c_iflags & CALLOUT_LOCAL_ALLOC)
c->c_iflags = CALLOUT_LOCAL_ALLOC;
else
c->c_iflags &= ~CALLOUT_PENDING;
cc_exec_curr(cc, direct) = c;
cc_exec_last_func(cc, direct) = c_func;
cc_exec_last_arg(cc, direct) = c_arg;
cc_exec_cancel(cc, direct) = false;
cc_exec_drain(cc, direct) = NULL;
CC_UNLOCK(cc);
if (c_lock != NULL) {
class->lc_lock(c_lock, lock_status);
/*
* The callout may have been cancelled
* while we switched locks.
*/
if (cc_exec_cancel(cc, direct)) {
class->lc_unlock(c_lock);
goto skip;
}
/* The callout cannot be stopped now. */
cc_exec_cancel(cc, direct) = true;
if (c_lock == &Giant.lock_object) {
#ifdef CALLOUT_PROFILING
(*gcalls)++;
#endif
CTR3(KTR_CALLOUT, "callout giant %p func %p arg %p",
c, c_func, c_arg);
} else {
#ifdef CALLOUT_PROFILING
(*lockcalls)++;
#endif
CTR3(KTR_CALLOUT, "callout lock %p func %p arg %p",
c, c_func, c_arg);
}
} else {
#ifdef CALLOUT_PROFILING
(*mpcalls)++;
#endif
CTR3(KTR_CALLOUT, "callout %p func %p arg %p",
c, c_func, c_arg);
}
KTR_STATE3(KTR_SCHED, "callout", cc->cc_ktr_event_name, "running",
"func:%p", c_func, "arg:%p", c_arg, "direct:%d", direct);
#if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING)
sbt1 = sbinuptime();
#endif
THREAD_NO_SLEEPING();
SDT_PROBE1(callout_execute, , , callout__start, c);
c_func(c_arg);
SDT_PROBE1(callout_execute, , , callout__end, c);
THREAD_SLEEPING_OK();
#if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING)
sbt2 = sbinuptime();
sbt2 -= sbt1;
if (sbt2 > maxdt) {
if (lastfunc != c_func || sbt2 > maxdt * 2) {
ts2 = sbttots(sbt2);
printf(
"Expensive timeout(9) function: %p(%p) %jd.%09ld s\n",
c_func, c_arg, (intmax_t)ts2.tv_sec, ts2.tv_nsec);
}
maxdt = sbt2;
lastfunc = c_func;
}
#endif
KTR_STATE0(KTR_SCHED, "callout", cc->cc_ktr_event_name, "idle");
CTR1(KTR_CALLOUT, "callout %p finished", c);
if ((c_iflags & CALLOUT_RETURNUNLOCKED) == 0)
class->lc_unlock(c_lock);
skip:
CC_LOCK(cc);
KASSERT(cc_exec_curr(cc, direct) == c, ("mishandled cc_curr"));
cc_exec_curr(cc, direct) = NULL;
if (cc_exec_drain(cc, direct)) {
void (*drain)(void *);
drain = cc_exec_drain(cc, direct);
cc_exec_drain(cc, direct) = NULL;
CC_UNLOCK(cc);
drain(c_arg);
CC_LOCK(cc);
}
if (cc_exec_waiting(cc, direct)) {
/*
* There is someone waiting for the
* callout to complete.
* If the callout was scheduled for
* migration just cancel it.
*/
if (cc_cce_migrating(cc, direct)) {
cc_cce_cleanup(cc, direct);
/*
* It should be assert here that the callout is not
* destroyed but that is not easy.
*/
c->c_iflags &= ~CALLOUT_DFRMIGRATION;
}
cc_exec_waiting(cc, direct) = false;
CC_UNLOCK(cc);
wakeup(&cc_exec_waiting(cc, direct));
CC_LOCK(cc);
} else if (cc_cce_migrating(cc, direct)) {
KASSERT((c_iflags & CALLOUT_LOCAL_ALLOC) == 0,
("Migrating legacy callout %p", c));
#ifdef SMP
/*
* If the callout was scheduled for
* migration just perform it now.
*/
new_cpu = cc_migration_cpu(cc, direct);
new_time = cc_migration_time(cc, direct);
new_prec = cc_migration_prec(cc, direct);
new_func = cc_migration_func(cc, direct);
new_arg = cc_migration_arg(cc, direct);
cc_cce_cleanup(cc, direct);
/*
* It should be assert here that the callout is not destroyed
* but that is not easy.
*
* As first thing, handle deferred callout stops.
*/
if (!callout_migrating(c)) {
CTR3(KTR_CALLOUT,
"deferred cancelled %p func %p arg %p",
c, new_func, new_arg);
callout_cc_del(c, cc);
return;
}
c->c_iflags &= ~CALLOUT_DFRMIGRATION;
new_cc = callout_cpu_switch(c, cc, new_cpu);
flags = (direct) ? C_DIRECT_EXEC : 0;
callout_cc_add(c, new_cc, new_time, new_prec, new_func,
new_arg, new_cpu, flags);
CC_UNLOCK(new_cc);
CC_LOCK(cc);
#else
panic("migration should not happen");
#endif
}
/*
* 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_iflags because
* if it was not local, then it's not safe to deref the
* callout pointer.
*/
KASSERT((c_iflags & CALLOUT_LOCAL_ALLOC) == 0 ||
c->c_iflags == CALLOUT_LOCAL_ALLOC,
("corrupted callout"));
if (c_iflags & CALLOUT_LOCAL_ALLOC)
callout_cc_del(c, 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;
#ifdef CALLOUT_PROFILING
int depth = 0, gcalls = 0, lockcalls = 0, mpcalls = 0;
#endif
cc = (struct callout_cpu *)arg;
CC_LOCK(cc);
while ((c = TAILQ_FIRST(&cc->cc_expireq)) != NULL) {
TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe);
softclock_call_cc(c, cc,
#ifdef CALLOUT_PROFILING
&mpcalls, &lockcalls, &gcalls,
#endif
0);
#ifdef CALLOUT_PROFILING
++depth;
#endif
}
#ifdef CALLOUT_PROFILING
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;
#endif
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(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(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;
}
void
callout_when(sbintime_t sbt, sbintime_t precision, int flags,
sbintime_t *res, sbintime_t *prec_res)
{
sbintime_t to_sbt, to_pr;
if ((flags & (C_ABSOLUTE | C_PRECALC)) != 0) {
*res = sbt;
*prec_res = precision;
return;
}
if ((flags & C_HARDCLOCK) != 0 && sbt < tick_sbt)
sbt = tick_sbt;
if ((flags & C_HARDCLOCK) != 0 ||
#ifdef NO_EVENTTIMERS
sbt >= sbt_timethreshold) {
to_sbt = getsbinuptime();
/* Add safety belt for the case of hz > 1000. */
to_sbt += tc_tick_sbt - tick_sbt;
#else
sbt >= sbt_tickthreshold) {
/*
* Obtain the time of the last hardclock() call on
* this CPU directly from the kern_clocksource.c.
* This value is per-CPU, but it is equal for all
* active ones.
*/
#ifdef __LP64__
to_sbt = DPCPU_GET(hardclocktime);
#else
spinlock_enter();
to_sbt = DPCPU_GET(hardclocktime);
spinlock_exit();
#endif
#endif
if (cold && to_sbt == 0)
to_sbt = sbinuptime();
if ((flags & C_HARDCLOCK) == 0)
to_sbt += tick_sbt;
} else
to_sbt = sbinuptime();
if (SBT_MAX - to_sbt < sbt)
to_sbt = SBT_MAX;
else
to_sbt += sbt;
*res = to_sbt;
to_pr = ((C_PRELGET(flags) < 0) ? sbt >> tc_precexp :
sbt >> C_PRELGET(flags));
*prec_res = to_pr > precision ? to_pr : precision;
}
/*
* 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_sbt_on(struct callout *c, sbintime_t sbt, sbintime_t prec,
void (*ftn)(void *), void *arg, int cpu, int flags)
{
sbintime_t to_sbt, precision;
struct callout_cpu *cc;
int cancelled, direct;
int ignore_cpu=0;
cancelled = 0;
if (cpu == -1) {
ignore_cpu = 1;
} else if ((cpu >= MAXCPU) ||
((CC_CPU(cpu))->cc_inited == 0)) {
/* Invalid CPU spec */
panic("Invalid CPU in callout %d", cpu);
}
callout_when(sbt, prec, flags, &to_sbt, &precision);
/*
* This flag used to be added by callout_cc_add, but the
* first time you call this we could end up with the
* wrong direct flag if we don't do it before we add.
*/
if (flags & C_DIRECT_EXEC) {
direct = 1;
} else {
direct = 0;
}
KASSERT(!direct || c->c_lock == NULL,
("%s: direct callout %p has lock", __func__, c));
cc = callout_lock(c);
/*
* Don't allow migration of pre-allocated callouts lest they
* become unbalanced or handle the case where the user does
* not care.
*/
if ((c->c_iflags & CALLOUT_LOCAL_ALLOC) ||
ignore_cpu) {
cpu = c->c_cpu;
}
if (cc_exec_curr(cc, direct) == 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_exec_cancel(cc, direct))
cancelled = cc_exec_cancel(cc, direct) = true;
if (cc_exec_waiting(cc, direct) || cc_exec_drain(cc, direct)) {
/*
* 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);
}
#ifdef SMP
if (callout_migrating(c)) {
/*
* This only occurs when a second callout_reset_sbt_on
* is made after a previous one moved it into
* deferred migration (below). Note we do *not* change
* the prev_cpu even though the previous target may
* be different.
*/
cc_migration_cpu(cc, direct) = cpu;
cc_migration_time(cc, direct) = to_sbt;
cc_migration_prec(cc, direct) = precision;
cc_migration_func(cc, direct) = ftn;
cc_migration_arg(cc, direct) = arg;
cancelled = 1;
CC_UNLOCK(cc);
return (cancelled);
}
#endif
}
if (c->c_iflags & CALLOUT_PENDING) {
if ((c->c_iflags & CALLOUT_PROCESSED) == 0) {
if (cc_exec_next(cc) == c)
cc_exec_next(cc) = LIST_NEXT(c, c_links.le);
LIST_REMOVE(c, c_links.le);
} else {
TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe);
}
cancelled = 1;
c->c_iflags &= ~ CALLOUT_PENDING;
c->c_flags &= ~ CALLOUT_ACTIVE;
}
#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_exec_curr(cc, direct) == c) {
/*
* Pending will have been removed since we are
* actually executing the callout on another
* CPU. That callout should be waiting on the
* lock the caller holds. If we set both
* active/and/pending after we return and the
* lock on the executing callout proceeds, it
* will then see pending is true and return.
* At the return from the actual callout execution
* the migration will occur in softclock_call_cc
* and this new callout will be placed on the
* new CPU via a call to callout_cpu_switch() which
* will get the lock on the right CPU followed
* by a call callout_cc_add() which will add it there.
* (see above in softclock_call_cc()).
*/
cc_migration_cpu(cc, direct) = cpu;
cc_migration_time(cc, direct) = to_sbt;
cc_migration_prec(cc, direct) = precision;
cc_migration_func(cc, direct) = ftn;
cc_migration_arg(cc, direct) = arg;
c->c_iflags |= (CALLOUT_DFRMIGRATION | CALLOUT_PENDING);
c->c_flags |= CALLOUT_ACTIVE;
CTR6(KTR_CALLOUT,
"migration of %p func %p arg %p in %d.%08x to %u deferred",
c, c->c_func, c->c_arg, (int)(to_sbt >> 32),
(u_int)(to_sbt & 0xffffffff), cpu);
CC_UNLOCK(cc);
return (cancelled);
}
cc = callout_cpu_switch(c, cc, cpu);
}
#endif
callout_cc_add(c, cc, to_sbt, precision, ftn, arg, cpu, flags);
CTR6(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d.%08x",
cancelled ? "re" : "", c, c->c_func, c->c_arg, (int)(to_sbt >> 32),
(u_int)(to_sbt & 0xffffffff));
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(struct callout *c, int flags, void (*drain)(void *))
{
struct callout_cpu *cc, *old_cc;
struct lock_class *class;
int direct, sq_locked, use_lock;
int cancelled, not_on_a_list;
if ((flags & CS_DRAIN) != 0)
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, c->c_lock,
"calling %s", __func__);
/*
* Some old subsystems don't hold Giant while running a callout_stop(),
* so just discard this check for the moment.
*/
if ((flags & CS_DRAIN) == 0 && 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;
if (c->c_iflags & CALLOUT_DIRECT) {
direct = 1;
} else {
direct = 0;
}
sq_locked = 0;
old_cc = NULL;
again:
cc = callout_lock(c);
if ((c->c_iflags & (CALLOUT_DFRMIGRATION | CALLOUT_PENDING)) ==
(CALLOUT_DFRMIGRATION | CALLOUT_PENDING) &&
((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE)) {
/*
* Special case where this slipped in while we
* were migrating *as* the callout is about to
* execute. The caller probably holds the lock
* the callout wants.
*
* Get rid of the migration first. Then set
* the flag that tells this code *not* to
* try to remove it from any lists (its not
* on one yet). When the callout wheel runs,
* it will ignore this callout.
*/
c->c_iflags &= ~CALLOUT_PENDING;
c->c_flags &= ~CALLOUT_ACTIVE;
not_on_a_list = 1;
} else {
not_on_a_list = 0;
}
/*
* 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(&cc_exec_waiting(old_cc, direct));
sq_locked = 0;
old_cc = NULL;
goto again;
#else
panic("migration should not happen");
#endif
}
/*
* If the callout is running, try to stop it or drain it.
*/
if (cc_exec_curr(cc, direct) == c) {
/*
* Succeed we to stop it or not, we must clear the
* active flag - this is what API users expect. If we're
* draining and the callout is currently executing, first wait
* until it finishes.
*/
if ((flags & CS_DRAIN) == 0)
c->c_flags &= ~CALLOUT_ACTIVE;
if ((flags & CS_DRAIN) != 0) {
/*
* 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_exec_curr(cc, direct) == 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_exec_waiting(cc, direct));
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_exec_waiting(cc, direct) = true;
DROP_GIANT();
CC_UNLOCK(cc);
sleepq_add(
&cc_exec_waiting(cc, direct),
&cc->cc_lock.lock_object, "codrain",
SLEEPQ_SLEEP, 0);
sleepq_wait(
&cc_exec_waiting(cc, direct),
0);
sq_locked = 0;
old_cc = NULL;
/* Reacquire locks previously released. */
PICKUP_GIANT();
CC_LOCK(cc);
}
c->c_flags &= ~CALLOUT_ACTIVE;
} else if (use_lock &&
!cc_exec_cancel(cc, direct) && (drain == NULL)) {
/*
* 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(). This *only* works with a
* callout_stop() *not* callout_drain() or
* callout_async_drain().
*/
cc_exec_cancel(cc, direct) = true;
CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p",
c, c->c_func, c->c_arg);
KASSERT(!cc_cce_migrating(cc, direct),
("callout wrongly scheduled for migration"));
if (callout_migrating(c)) {
c->c_iflags &= ~CALLOUT_DFRMIGRATION;
#ifdef SMP
cc_migration_cpu(cc, direct) = CPUBLOCK;
cc_migration_time(cc, direct) = 0;
cc_migration_prec(cc, direct) = 0;
cc_migration_func(cc, direct) = NULL;
cc_migration_arg(cc, direct) = NULL;
#endif
}
CC_UNLOCK(cc);
KASSERT(!sq_locked, ("sleepqueue chain locked"));
return (1);
} else if (callout_migrating(c)) {
/*
* The callout is currently being serviced
* and the "next" callout is scheduled at
* its completion with a migration. We remove
* the migration flag so it *won't* get rescheduled,
* but we can't stop the one thats running so
* we return 0.
*/
c->c_iflags &= ~CALLOUT_DFRMIGRATION;
#ifdef SMP
/*
* We can't call cc_cce_cleanup here since
* if we do it will remove .ce_curr and
* its still running. This will prevent a
* reschedule of the callout when the
* execution completes.
*/
cc_migration_cpu(cc, direct) = CPUBLOCK;
cc_migration_time(cc, direct) = 0;
cc_migration_prec(cc, direct) = 0;
cc_migration_func(cc, direct) = NULL;
cc_migration_arg(cc, direct) = NULL;
#endif
CTR3(KTR_CALLOUT, "postponing stop %p func %p arg %p",
c, c->c_func, c->c_arg);
if (drain) {
cc_exec_drain(cc, direct) = drain;
}
CC_UNLOCK(cc);
return ((flags & CS_EXECUTING) != 0);
}
CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
c, c->c_func, c->c_arg);
if (drain) {
cc_exec_drain(cc, direct) = drain;
}
KASSERT(!sq_locked, ("sleepqueue chain still locked"));
cancelled = ((flags & CS_EXECUTING) != 0);
} else
cancelled = 1;
if (sq_locked)
sleepq_release(&cc_exec_waiting(cc, direct));
if ((c->c_iflags & CALLOUT_PENDING) == 0) {
CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
c, c->c_func, c->c_arg);
/*
* For not scheduled and not executing callout return
* negative value.
*/
if (cc_exec_curr(cc, direct) != c)
cancelled = -1;
CC_UNLOCK(cc);
return (cancelled);
}
c->c_iflags &= ~CALLOUT_PENDING;
c->c_flags &= ~CALLOUT_ACTIVE;
CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p",
c, c->c_func, c->c_arg);
if (not_on_a_list == 0) {
if ((c->c_iflags & CALLOUT_PROCESSED) == 0) {
if (cc_exec_next(cc) == c)
cc_exec_next(cc) = LIST_NEXT(c, c_links.le);
LIST_REMOVE(c, c_links.le);
} else {
TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe);
}
}
callout_cc_del(c, cc);
CC_UNLOCK(cc);
return (cancelled);
}
void
callout_init(struct callout *c, int mpsafe)
{
bzero(c, sizeof *c);
if (mpsafe) {
c->c_lock = NULL;
c->c_iflags = CALLOUT_RETURNUNLOCKED;
} else {
c->c_lock = &Giant.lock_object;
c->c_iflags = 0;
}
c->c_cpu = timeout_cpu;
}
void
_callout_init_lock(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_iflags = 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 independent on whether the suspend was 2 hours or
* 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu>
*/
void
adjust_timeout_calltodo(struct timeval *time_change)
{
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 = howmany(time_change->tv_sec * 1000000 +
time_change->tv_usec, tick) + 1;
else if (time_change->tv_sec <= LONG_MAX / hz)
delta_ticks = time_change->tv_sec * hz +
howmany(time_change->tv_usec, 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 */
static int
flssbt(sbintime_t sbt)
{
sbt += (uint64_t)sbt >> 1;
if (sizeof(long) >= sizeof(sbintime_t))
return (flsl(sbt));
if (sbt >= SBT_1S)
return (flsl(((uint64_t)sbt) >> 32) + 32);
return (flsl(sbt));
}
/*
* Dump immediate statistic snapshot of the scheduled callouts.
*/
static int
sysctl_kern_callout_stat(SYSCTL_HANDLER_ARGS)
{
struct callout *tmp;
struct callout_cpu *cc;
struct callout_list *sc;
sbintime_t maxpr, maxt, medpr, medt, now, spr, st, t;
int ct[64], cpr[64], ccpbk[32];
int error, val, i, count, tcum, pcum, maxc, c, medc;
#ifdef SMP
int cpu;
#endif
val = 0;
error = sysctl_handle_int(oidp, &val, 0, req);
if (error != 0 || req->newptr == NULL)
return (error);
count = maxc = 0;
st = spr = maxt = maxpr = 0;
bzero(ccpbk, sizeof(ccpbk));
bzero(ct, sizeof(ct));
bzero(cpr, sizeof(cpr));
now = sbinuptime();
#ifdef SMP
CPU_FOREACH(cpu) {
cc = CC_CPU(cpu);
#else
cc = CC_CPU(timeout_cpu);
#endif
CC_LOCK(cc);
for (i = 0; i < callwheelsize; i++) {
sc = &cc->cc_callwheel[i];
c = 0;
LIST_FOREACH(tmp, sc, c_links.le) {
c++;
t = tmp->c_time - now;
if (t < 0)
t = 0;
st += t / SBT_1US;
spr += tmp->c_precision / SBT_1US;
if (t > maxt)
maxt = t;
if (tmp->c_precision > maxpr)
maxpr = tmp->c_precision;
ct[flssbt(t)]++;
cpr[flssbt(tmp->c_precision)]++;
}
if (c > maxc)
maxc = c;
ccpbk[fls(c + c / 2)]++;
count += c;
}
CC_UNLOCK(cc);
#ifdef SMP
}
#endif
for (i = 0, tcum = 0; i < 64 && tcum < count / 2; i++)
tcum += ct[i];
medt = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0;
for (i = 0, pcum = 0; i < 64 && pcum < count / 2; i++)
pcum += cpr[i];
medpr = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0;
for (i = 0, c = 0; i < 32 && c < count / 2; i++)
c += ccpbk[i];
medc = (i >= 2) ? (1 << (i - 2)) : 0;
printf("Scheduled callouts statistic snapshot:\n");
printf(" Callouts: %6d Buckets: %6d*%-3d Bucket size: 0.%06ds\n",
count, callwheelsize, mp_ncpus, 1000000 >> CC_HASH_SHIFT);
printf(" C/Bk: med %5d avg %6d.%06jd max %6d\n",
medc,
count / callwheelsize / mp_ncpus,
(uint64_t)count * 1000000 / callwheelsize / mp_ncpus % 1000000,
maxc);
printf(" Time: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n",
medt / SBT_1S, (medt & 0xffffffff) * 1000000 >> 32,
(st / count) / 1000000, (st / count) % 1000000,
maxt / SBT_1S, (maxt & 0xffffffff) * 1000000 >> 32);
printf(" Prec: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n",
medpr / SBT_1S, (medpr & 0xffffffff) * 1000000 >> 32,
(spr / count) / 1000000, (spr / count) % 1000000,
maxpr / SBT_1S, (maxpr & 0xffffffff) * 1000000 >> 32);
printf(" Distribution: \tbuckets\t time\t tcum\t"
" prec\t pcum\n");
for (i = 0, tcum = pcum = 0; i < 64; i++) {
if (ct[i] == 0 && cpr[i] == 0)
continue;
t = (i != 0) ? (((sbintime_t)1) << (i - 1)) : 0;
tcum += ct[i];
pcum += cpr[i];
printf(" %10jd.%06jds\t 2**%d\t%7d\t%7d\t%7d\t%7d\n",
t / SBT_1S, (t & 0xffffffff) * 1000000 >> 32,
i - 1 - (32 - CC_HASH_SHIFT),
ct[i], tcum, cpr[i], pcum);
}
return (error);
}
SYSCTL_PROC(_kern, OID_AUTO, callout_stat,
CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
0, 0, sysctl_kern_callout_stat, "I",
"Dump immediate statistic snapshot of the scheduled callouts");
#ifdef DDB
static void
_show_callout(struct callout *c)
{
db_printf("callout %p\n", c);
#define C_DB_PRINTF(f, e) db_printf(" %s = " f "\n", #e, c->e);
db_printf(" &c_links = %p\n", &(c->c_links));
C_DB_PRINTF("%" PRId64, c_time);
C_DB_PRINTF("%" PRId64, c_precision);
C_DB_PRINTF("%p", c_arg);
C_DB_PRINTF("%p", c_func);
C_DB_PRINTF("%p", c_lock);
C_DB_PRINTF("%#x", c_flags);
C_DB_PRINTF("%#x", c_iflags);
C_DB_PRINTF("%d", c_cpu);
#undef C_DB_PRINTF
}
DB_SHOW_COMMAND(callout, db_show_callout)
{
if (!have_addr) {
db_printf("usage: show callout <struct callout *>\n");
return;
}
_show_callout((struct callout *)addr);
}
static void
_show_last_callout(int cpu, int direct, const char *dirstr)
{
struct callout_cpu *cc;
void *func, *arg;
cc = CC_CPU(cpu);
func = cc_exec_last_func(cc, direct);
arg = cc_exec_last_arg(cc, direct);
db_printf("cpu %d last%s callout function: %p ", cpu, dirstr, func);
db_printsym((db_expr_t)func, DB_STGY_ANY);
db_printf("\ncpu %d last%s callout argument: %p\n", cpu, dirstr, arg);
}
DB_SHOW_COMMAND(callout_last, db_show_callout_last)
{
int cpu, last;
if (have_addr) {
if (addr < 0 || addr > mp_maxid || CPU_ABSENT(addr)) {
db_printf("no such cpu: %d\n", (int)addr);
return;
}
cpu = last = addr;
} else {
cpu = 0;
last = mp_maxid;
}
while (cpu <= last) {
if (!CPU_ABSENT(cpu)) {
_show_last_callout(cpu, 0, "");
_show_last_callout(cpu, 1, " direct");
}
cpu++;
}
}
#endif /* DDB */
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