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📄 Make.tags.inc(2.13 KB)
📄 Makefile(302 B)
📄 bus_if.m(26.31 KB)
📄 capabilities.conf(13.67 KB)
📄 clock_if.m(1.7 KB)
📄 cpufreq_if.m(2.27 KB)
📄 device_if.m(10.41 KB)
📄 firmw.S(2.15 KB)
📄 genassym.sh(1.11 KB)
📄 genoffset.c(1.68 KB)
📄 genoffset.sh(3.58 KB)
📄 imgact_aout.c(9.45 KB)
📄 imgact_binmisc.c(18.64 KB)
📄 imgact_elf.c(76.32 KB)
📄 imgact_elf32.c(1.47 KB)
📄 imgact_elf64.c(1.47 KB)
📄 imgact_shell.c(8.41 KB)
📄 init_main.c(24.31 KB)
📄 init_sysent.c(95.3 KB)
📄 kern_acct.c(19.03 KB)
📄 kern_alq.c(24.97 KB)
📄 kern_clock.c(21.12 KB)
📄 kern_clocksource.c(23.34 KB)
📄 kern_condvar.c(11.28 KB)
📄 kern_conf.c(36.14 KB)
📄 kern_cons.c(15.75 KB)
📄 kern_context.c(3.59 KB)
📄 kern_cpu.c(30.77 KB)
📄 kern_cpuset.c(59.78 KB)
📄 kern_ctf.c(8.73 KB)
📄 kern_descrip.c(112.87 KB)
📄 kern_dtrace.c(2.94 KB)
📄 kern_dump.c(8.51 KB)
📄 kern_environment.c(22.75 KB)
📄 kern_et.c(7.1 KB)
📄 kern_event.c(62.49 KB)
📄 kern_exec.c(46.67 KB)
📄 kern_exit.c(34.61 KB)
📄 kern_fail.c(29.32 KB)
📄 kern_ffclock.c(12.66 KB)
📄 kern_fork.c(28.29 KB)
📄 kern_hhook.c(13.58 KB)
📄 kern_idle.c(2.74 KB)
📄 kern_intr.c(40.44 KB)
📄 kern_jail.c(112.67 KB)
📄 kern_kcov.c(15.32 KB)
📄 kern_khelp.c(9.45 KB)
📄 kern_kthread.c(11.8 KB)
📄 kern_ktr.c(11.93 KB)
📄 kern_ktrace.c(31.41 KB)
📄 kern_linker.c(54.3 KB)
📄 kern_lock.c(46.99 KB)
📄 kern_lockf.c(64.46 KB)
📄 kern_lockstat.c(3.8 KB)
📄 kern_loginclass.c(6.69 KB)
📄 kern_malloc.c(37.09 KB)
📄 kern_mbuf.c(43.16 KB)
📄 kern_mib.c(24.26 KB)
📄 kern_module.c(11.05 KB)
📄 kern_mtxpool.c(5.82 KB)
📄 kern_mutex.c(33.62 KB)
📄 kern_ntptime.c(32.49 KB)
📄 kern_osd.c(12.37 KB)
📄 kern_physio.c(5.74 KB)
📄 kern_pmc.c(8.89 KB)
📄 kern_poll.c(15.86 KB)
📄 kern_priv.c(9.14 KB)
📄 kern_proc.c(80.01 KB)
📄 kern_procctl.c(19.48 KB)
📄 kern_prot.c(57.94 KB)
📄 kern_racct.c(34.01 KB)
📄 kern_rangelock.c(8.67 KB)
📄 kern_rctl.c(53.87 KB)
📄 kern_resource.c(36.66 KB)
📄 kern_rmlock.c(28.27 KB)
📄 kern_rwlock.c(40.72 KB)
📄 kern_sdt.c(2.05 KB)
📄 kern_sema.c(4.85 KB)
📄 kern_sendfile.c(33.97 KB)
📄 kern_sharedpage.c(10.37 KB)
📄 kern_shutdown.c(43.34 KB)
📄 kern_sig.c(101.89 KB)
📄 kern_switch.c(13.85 KB)
📄 kern_sx.c(40.27 KB)
📄 kern_synch.c(18.17 KB)
📄 kern_syscalls.c(6.74 KB)
📄 kern_sysctl.c(67.24 KB)
📄 kern_tc.c(55.73 KB)
📄 kern_thr.c(14.14 KB)
📄 kern_thread.c(41.75 KB)
📄 kern_time.c(40.89 KB)
📄 kern_timeout.c(43.08 KB)
📄 kern_tslog.c(3.44 KB)
📄 kern_ubsan.c(50.74 KB)
📄 kern_umtx.c(107.14 KB)
📄 kern_uuid.c(11.68 KB)
📄 kern_xxx.c(10.44 KB)
📄 ksched.c(6.56 KB)
📄 link_elf.c(47.99 KB)
📄 link_elf_obj.c(44.41 KB)
📄 linker_if.m(3.96 KB)
📄 makesyscalls.sh(23.57 KB)
📄 md4c.c(7.89 KB)
📄 md5c.c(9.56 KB)
📄 msi_if.m(2.48 KB)
📄 p1003_1b.c(8.84 KB)
📄 pic_if.m(3.9 KB)
📄 posix4_mib.c(5.59 KB)
📄 sched_4bsd.c(45.03 KB)
📄 sched_ule.c(82.65 KB)
📄 serdev_if.m(3.49 KB)
📄 stack_protector.c(613 B)
📄 subr_acl_nfs4.c(37.42 KB)
📄 subr_acl_posix1e.c(17.71 KB)
📄 subr_atomic64.c(3.97 KB)
📄 subr_autoconf.c(7.7 KB)
📄 subr_blist.c(31.88 KB)
📄 subr_boot.c(5.8 KB)
📄 subr_bufring.c(2.21 KB)
📄 subr_bus.c(145.4 KB)
📄 subr_bus_dma.c(19.67 KB)
📄 subr_busdma_bufalloc.c(5.24 KB)
📄 subr_capability.c(11.93 KB)
📄 subr_clock.c(10.61 KB)
📄 subr_compressor.c(13.11 KB)
📄 subr_counter.c(4.44 KB)
📄 subr_coverage.c(6.17 KB)
📄 subr_csan.c(25.39 KB)
📄 subr_devmap.c(9.8 KB)
📄 subr_devstat.c(16.21 KB)
📄 subr_disk.c(8.54 KB)
📄 subr_dummy_vdso_tc.c(1.7 KB)
📄 subr_early.c(2.26 KB)
📄 subr_epoch.c(25.02 KB)
📄 subr_eventhandler.c(9.17 KB)
📄 subr_fattime.c(9.98 KB)
📄 subr_filter.c(12.2 KB)
📄 subr_firmware.c(13.88 KB)
📄 subr_gtaskqueue.c(20.19 KB)
📄 subr_hash.c(4.8 KB)
📄 subr_hints.c(12.87 KB)
📄 subr_intr.c(40.61 KB)
📄 subr_kdb.c(16.13 KB)
📄 subr_kobj.c(7.1 KB)
📄 subr_lock.c(18.81 KB)
📄 subr_log.c(7.64 KB)
📄 subr_mchain.c(11.06 KB)
📄 subr_module.c(12.98 KB)
📄 subr_msgbuf.c(10.6 KB)
📄 subr_param.c(10.93 KB)
📄 subr_pcpu.c(10.18 KB)
📄 subr_pctrie.c(20.99 KB)
📄 subr_physmem.c(11.52 KB)
📄 subr_pidctrl.c(5.43 KB)
📄 subr_power.c(3.13 KB)
📄 subr_prf.c(27.42 KB)
📄 subr_prng.c(3.36 KB)
📄 subr_prof.c(15.43 KB)
📄 subr_rangeset.c(8.5 KB)
📄 subr_rman.c(27.61 KB)
📄 subr_rtc.c(11.42 KB)
📄 subr_sbuf.c(20.53 KB)
📄 subr_scanf.c(15.59 KB)
📄 subr_sfbuf.c(6.17 KB)
📄 subr_sglist.c(22.83 KB)
📄 subr_sleepqueue.c(39.43 KB)
📄 subr_smp.c(31.62 KB)
📄 subr_smr.c(20.17 KB)
📄 subr_stack.c(6.47 KB)
📄 subr_stats.c(103.01 KB)
📄 subr_syscall.c(7.98 KB)
📄 subr_taskqueue.c(21.1 KB)
📄 subr_terminal.c(15.52 KB)
📄 subr_trap.c(10.87 KB)
📄 subr_turnstile.c(35.58 KB)
📄 subr_uio.c(11.38 KB)
📄 subr_unit.c(22.97 KB)
📄 subr_vmem.c(43.25 KB)
📄 subr_witness.c(84.59 KB)
📄 sys_capability.c(15.06 KB)
📄 sys_eventfd.c(8.42 KB)
📄 sys_generic.c(44.22 KB)
📄 sys_getrandom.c(4.21 KB)
📄 sys_pipe.c(45.14 KB)
📄 sys_procdesc.c(14.57 KB)
📄 sys_process.c(30.73 KB)
📄 sys_socket.c(20.11 KB)
📄 syscalls.c(22.73 KB)
📄 syscalls.master(60.26 KB)
📄 systrace_args.c(178.49 KB)
📄 sysv_ipc.c(6.53 KB)
📄 sysv_msg.c(48.65 KB)
📄 sysv_sem.c(49.85 KB)
📄 sysv_shm.c(43.93 KB)
📄 tty.c(55.14 KB)
📄 tty_compat.c(11.46 KB)
📄 tty_info.c(9.93 KB)
📄 tty_inq.c(12.22 KB)
📄 tty_outq.c(8.74 KB)
📄 tty_pts.c(19.74 KB)
📄 tty_tty.c(2.83 KB)
📄 tty_ttydisc.c(28.6 KB)
📄 uipc_accf.c(8.07 KB)
📄 uipc_debug.c(12.42 KB)
📄 uipc_domain.c(13.13 KB)
📄 uipc_ktls.c(55.7 KB)
📄 uipc_mbuf.c(52.45 KB)
📄 uipc_mbuf2.c(12.64 KB)
📄 uipc_mbufhash.c(4.9 KB)
📄 uipc_mqueue.c(64.64 KB)
📄 uipc_sem.c(25.18 KB)
📄 uipc_shm.c(50.47 KB)
📄 uipc_sockbuf.c(42.9 KB)
📄 uipc_socket.c(110.61 KB)
📄 uipc_syscalls.c(35.94 KB)
📄 uipc_usrreq.c(75.11 KB)
📄 vfs_acl.c(14.5 KB)
📄 vfs_aio.c(76.32 KB)
📄 vfs_bio.c(145.39 KB)
📄 vfs_cache.c(143.09 KB)
📄 vfs_cluster.c(28.36 KB)
📄 vfs_default.c(33.16 KB)
📄 vfs_export.c(14.55 KB)
📄 vfs_extattr.c(17.91 KB)
📄 vfs_hash.c(6 KB)
📄 vfs_init.c(15.86 KB)
📄 vfs_lookup.c(45.48 KB)
📄 vfs_mount.c(62.58 KB)
📄 vfs_mountroot.c(26.23 KB)
📄 vfs_subr.c(167.52 KB)
📄 vfs_syscalls.c(106.86 KB)
📄 vfs_vnops.c(86.28 KB)
📄 vnode_if.src(13.66 KB)

Editing: kern_synch.c

/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1982, 1986, 1990, 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.
 *
 *	@(#)kern_synch.c	8.9 (Berkeley) 5/19/95
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include "opt_ktrace.h"
#include "opt_sched.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/blockcount.h>
#include <sys/condvar.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/sched.h>
#include <sys/sdt.h>
#include <sys/signalvar.h>
#include <sys/sleepqueue.h>
#include <sys/smp.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/sysproto.h>
#include <sys/vmmeter.h>
#ifdef KTRACE
#include <sys/uio.h>
#include <sys/ktrace.h>
#endif
#ifdef EPOCH_TRACE
#include <sys/epoch.h>
#endif

#include <machine/cpu.h>

static void synch_setup(void *dummy);
SYSINIT(synch_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, synch_setup,
    NULL);

int	hogticks;
static const char pause_wchan[MAXCPU];

static struct callout loadav_callout;

struct loadavg averunnable =
	{ {0, 0, 0}, FSCALE };	/* load average, of runnable procs */
/*
 * Constants for averages over 1, 5, and 15 minutes
 * when sampling at 5 second intervals.
 */
static fixpt_t cexp[3] = {
	0.9200444146293232 * FSCALE,	/* exp(-1/12) */
	0.9834714538216174 * FSCALE,	/* exp(-1/60) */
	0.9944598480048967 * FSCALE,	/* exp(-1/180) */
};

/* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */
SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, SYSCTL_NULL_INT_PTR, FSCALE,
    "Fixed-point scale factor used for calculating load average values");

static void	loadav(void *arg);

SDT_PROVIDER_DECLARE(sched);
SDT_PROBE_DEFINE(sched, , , preempt);

static void
sleepinit(void *unused)
{

hogticks = (hz / 10) * 2;	/* Default only. */
	init_sleepqueues();
}

/*
 * vmem tries to lock the sleepq mutexes when free'ing kva, so make sure
 * it is available.
 */
SYSINIT(sleepinit, SI_SUB_KMEM, SI_ORDER_ANY, sleepinit, NULL);

/*
 * General sleep call.  Suspends the current thread until a wakeup is
 * performed on the specified identifier.  The thread will then be made
 * runnable with the specified priority.  Sleeps at most sbt units of time
 * (0 means no timeout).  If pri includes the PCATCH flag, let signals
 * interrupt the sleep, otherwise ignore them while sleeping.  Returns 0 if
 * awakened, EWOULDBLOCK if the timeout expires.  If PCATCH is set and a
 * signal becomes pending, ERESTART is returned if the current system
 * call should be restarted if possible, and EINTR is returned if the system
 * call should be interrupted by the signal (return EINTR).
 *
 * The lock argument is unlocked before the caller is suspended, and
 * re-locked before _sleep() returns.  If priority includes the PDROP
 * flag the lock is not re-locked before returning.
 */
int
_sleep(const void *ident, struct lock_object *lock, int priority,
    const char *wmesg, sbintime_t sbt, sbintime_t pr, int flags)
{
	struct thread *td;
	struct lock_class *class;
	uintptr_t lock_state;
	int catch, pri, rval, sleepq_flags;
	WITNESS_SAVE_DECL(lock_witness);

td = curthread;
#ifdef KTRACE
	if (KTRPOINT(td, KTR_CSW))
		ktrcsw(1, 0, wmesg);
#endif
	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, lock,
	    "Sleeping on \"%s\"", wmesg);
	KASSERT(sbt != 0 || mtx_owned(&Giant) || lock != NULL,
	    ("sleeping without a lock"));
	KASSERT(ident != NULL, ("_sleep: NULL ident"));
	KASSERT(TD_IS_RUNNING(td), ("_sleep: curthread not running"));
	if (priority & PDROP)
		KASSERT(lock != NULL && lock != &Giant.lock_object,
		    ("PDROP requires a non-Giant lock"));
	if (lock != NULL)
		class = LOCK_CLASS(lock);
	else
		class = NULL;

if (SCHEDULER_STOPPED_TD(td)) {
		if (lock != NULL && priority & PDROP)
			class->lc_unlock(lock);
		return (0);
	}
	catch = priority & PCATCH;
	pri = priority & PRIMASK;

KASSERT(!TD_ON_SLEEPQ(td), ("recursive sleep"));

if ((uintptr_t)ident >= (uintptr_t)&pause_wchan[0] &&
	    (uintptr_t)ident <= (uintptr_t)&pause_wchan[MAXCPU - 1])
		sleepq_flags = SLEEPQ_PAUSE;
	else
		sleepq_flags = SLEEPQ_SLEEP;
	if (catch)
		sleepq_flags |= SLEEPQ_INTERRUPTIBLE;

sleepq_lock(ident);
	CTR5(KTR_PROC, "sleep: thread %ld (pid %ld, %s) on %s (%p)",
	    td->td_tid, td->td_proc->p_pid, td->td_name, wmesg, ident);

if (lock == &Giant.lock_object)
		mtx_assert(&Giant, MA_OWNED);
	DROP_GIANT();
	if (lock != NULL && lock != &Giant.lock_object &&
	    !(class->lc_flags & LC_SLEEPABLE)) {
		WITNESS_SAVE(lock, lock_witness);
		lock_state = class->lc_unlock(lock);
	} else
		/* GCC needs to follow the Yellow Brick Road */
		lock_state = -1;

/*
	 * We put ourselves on the sleep queue and start our timeout
	 * before calling thread_suspend_check, as we could stop there,
	 * and a wakeup or a SIGCONT (or both) could occur while we were
	 * stopped without resuming us.  Thus, we must be ready for sleep
	 * when cursig() is called.  If the wakeup happens while we're
	 * stopped, then td will no longer be on a sleep queue upon
	 * return from cursig().
	 */
	sleepq_add(ident, lock, wmesg, sleepq_flags, 0);
	if (sbt != 0)
		sleepq_set_timeout_sbt(ident, sbt, pr, flags);
	if (lock != NULL && class->lc_flags & LC_SLEEPABLE) {
		sleepq_release(ident);
		WITNESS_SAVE(lock, lock_witness);
		lock_state = class->lc_unlock(lock);
		sleepq_lock(ident);
	}
	if (sbt != 0 && catch)
		rval = sleepq_timedwait_sig(ident, pri);
	else if (sbt != 0)
		rval = sleepq_timedwait(ident, pri);
	else if (catch)
		rval = sleepq_wait_sig(ident, pri);
	else {
		sleepq_wait(ident, pri);
		rval = 0;
	}
#ifdef KTRACE
	if (KTRPOINT(td, KTR_CSW))
		ktrcsw(0, 0, wmesg);
#endif
	PICKUP_GIANT();
	if (lock != NULL && lock != &Giant.lock_object && !(priority & PDROP)) {
		class->lc_lock(lock, lock_state);
		WITNESS_RESTORE(lock, lock_witness);
	}
	return (rval);
}

int
msleep_spin_sbt(const void *ident, struct mtx *mtx, const char *wmesg,
    sbintime_t sbt, sbintime_t pr, int flags)
{
	struct thread *td;
	int rval;
	WITNESS_SAVE_DECL(mtx);

td = curthread;
	KASSERT(mtx != NULL, ("sleeping without a mutex"));
	KASSERT(ident != NULL, ("msleep_spin_sbt: NULL ident"));
	KASSERT(TD_IS_RUNNING(td), ("msleep_spin_sbt: curthread not running"));

if (SCHEDULER_STOPPED_TD(td))
		return (0);

sleepq_lock(ident);
	CTR5(KTR_PROC, "msleep_spin: thread %ld (pid %ld, %s) on %s (%p)",
	    td->td_tid, td->td_proc->p_pid, td->td_name, wmesg, ident);

DROP_GIANT();
	mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED);
	WITNESS_SAVE(&mtx->lock_object, mtx);
	mtx_unlock_spin(mtx);

/*
	 * We put ourselves on the sleep queue and start our timeout.
	 */
	sleepq_add(ident, &mtx->lock_object, wmesg, SLEEPQ_SLEEP, 0);
	if (sbt != 0)
		sleepq_set_timeout_sbt(ident, sbt, pr, flags);

/*
	 * Can't call ktrace with any spin locks held so it can lock the
	 * ktrace_mtx lock, and WITNESS_WARN considers it an error to hold
	 * any spin lock.  Thus, we have to drop the sleepq spin lock while
	 * we handle those requests.  This is safe since we have placed our
	 * thread on the sleep queue already.
	 */
#ifdef KTRACE
	if (KTRPOINT(td, KTR_CSW)) {
		sleepq_release(ident);
		ktrcsw(1, 0, wmesg);
		sleepq_lock(ident);
	}
#endif
#ifdef WITNESS
	sleepq_release(ident);
	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "Sleeping on \"%s\"",
	    wmesg);
	sleepq_lock(ident);
#endif
	if (sbt != 0)
		rval = sleepq_timedwait(ident, 0);
	else {
		sleepq_wait(ident, 0);
		rval = 0;
	}
#ifdef KTRACE
	if (KTRPOINT(td, KTR_CSW))
		ktrcsw(0, 0, wmesg);
#endif
	PICKUP_GIANT();
	mtx_lock_spin(mtx);
	WITNESS_RESTORE(&mtx->lock_object, mtx);
	return (rval);
}

/*
 * pause_sbt() delays the calling thread by the given signed binary
 * time. During cold bootup, pause_sbt() uses the DELAY() function
 * instead of the _sleep() function to do the waiting. The "sbt"
 * argument must be greater than or equal to zero. A "sbt" value of
 * zero is equivalent to a "sbt" value of one tick.
 */
int
pause_sbt(const char *wmesg, sbintime_t sbt, sbintime_t pr, int flags)
{
	KASSERT(sbt >= 0, ("pause_sbt: timeout must be >= 0"));

/* silently convert invalid timeouts */
	if (sbt == 0)
		sbt = tick_sbt;

if ((cold && curthread == &thread0) || kdb_active ||
	    SCHEDULER_STOPPED()) {
		/*
		 * We delay one second at a time to avoid overflowing the
		 * system specific DELAY() function(s):
		 */
		while (sbt >= SBT_1S) {
			DELAY(1000000);
			sbt -= SBT_1S;
		}
		/* Do the delay remainder, if any */
		sbt = howmany(sbt, SBT_1US);
		if (sbt > 0)
			DELAY(sbt);
		return (EWOULDBLOCK);
	}
	return (_sleep(&pause_wchan[curcpu], NULL,
	    (flags & C_CATCH) ? PCATCH : 0, wmesg, sbt, pr, flags));
}

/*
 * Make all threads sleeping on the specified identifier runnable.
 */
void
wakeup(const void *ident)
{
	int wakeup_swapper;

sleepq_lock(ident);
	wakeup_swapper = sleepq_broadcast(ident, SLEEPQ_SLEEP, 0, 0);
	sleepq_release(ident);
	if (wakeup_swapper) {
		KASSERT(ident != &proc0,
		    ("wakeup and wakeup_swapper and proc0"));
		kick_proc0();
	}
}

/*
 * Make a thread sleeping on the specified identifier runnable.
 * May wake more than one thread if a target thread is currently
 * swapped out.
 */
void
wakeup_one(const void *ident)
{
	int wakeup_swapper;

sleepq_lock(ident);
	wakeup_swapper = sleepq_signal(ident, SLEEPQ_SLEEP, 0, 0);
	sleepq_release(ident);
	if (wakeup_swapper)
		kick_proc0();
}

void
wakeup_any(const void *ident)
{
	int wakeup_swapper;

sleepq_lock(ident);
	wakeup_swapper = sleepq_signal(ident, SLEEPQ_SLEEP | SLEEPQ_UNFAIR,
	    0, 0);
	sleepq_release(ident);
	if (wakeup_swapper)
		kick_proc0();
}

/*
 * Signal sleeping waiters after the counter has reached zero.
 */
void
_blockcount_wakeup(blockcount_t *bc, u_int old)
{

KASSERT(_BLOCKCOUNT_WAITERS(old),
	    ("%s: no waiters on %p", __func__, bc));

if (atomic_cmpset_int(&bc->__count, _BLOCKCOUNT_WAITERS_FLAG, 0))
		wakeup(bc);
}

/*
 * Wait for a wakeup or a signal.  This does not guarantee that the count is
 * still zero on return.  Callers wanting a precise answer should use
 * blockcount_wait() with an interlock.
 *
 * If there is no work to wait for, return 0.  If the sleep was interrupted by a
 * signal, return EINTR or ERESTART, and return EAGAIN otherwise.
 */
int
_blockcount_sleep(blockcount_t *bc, struct lock_object *lock, const char *wmesg,
    int prio)
{
	void *wchan;
	uintptr_t lock_state;
	u_int old;
	int ret;
	bool catch, drop;

KASSERT(lock != &Giant.lock_object,
	    ("%s: cannot use Giant as the interlock", __func__));

catch = (prio & PCATCH) != 0;
	drop = (prio & PDROP) != 0;
	prio &= PRIMASK;

/*
	 * Synchronize with the fence in blockcount_release().  If we end up
	 * waiting, the sleepqueue lock acquisition will provide the required
	 * side effects.
	 *
	 * If there is no work to wait for, but waiters are present, try to put
	 * ourselves to sleep to avoid jumping ahead.
	 */
	if (atomic_load_acq_int(&bc->__count) == 0) {
		if (lock != NULL && drop)
			LOCK_CLASS(lock)->lc_unlock(lock);
		return (0);
	}
	lock_state = 0;
	wchan = bc;
	sleepq_lock(wchan);
	DROP_GIANT();
	if (lock != NULL)
		lock_state = LOCK_CLASS(lock)->lc_unlock(lock);
	old = blockcount_read(bc);
	ret = 0;
	do {
		if (_BLOCKCOUNT_COUNT(old) == 0) {
			sleepq_release(wchan);
			goto out;
		}
		if (_BLOCKCOUNT_WAITERS(old))
			break;
	} while (!atomic_fcmpset_int(&bc->__count, &old,
	    old | _BLOCKCOUNT_WAITERS_FLAG));
	sleepq_add(wchan, NULL, wmesg, catch ? SLEEPQ_INTERRUPTIBLE : 0, 0);
	if (catch)
		ret = sleepq_wait_sig(wchan, prio);
	else
		sleepq_wait(wchan, prio);
	if (ret == 0)
		ret = EAGAIN;

out:
	PICKUP_GIANT();
	if (lock != NULL && !drop)
		LOCK_CLASS(lock)->lc_lock(lock, lock_state);

return (ret);
}

static void
kdb_switch(void)
{
	thread_unlock(curthread);
	kdb_backtrace();
	kdb_reenter();
	panic("%s: did not reenter debugger", __func__);
}

/*
 * The machine independent parts of context switching.
 *
 * The thread lock is required on entry and is no longer held on return.
 */
void
mi_switch(int flags)
{
	uint64_t runtime, new_switchtime;
	struct thread *td;

td = curthread;			/* XXX */
	THREAD_LOCK_ASSERT(td, MA_OWNED | MA_NOTRECURSED);
	KASSERT(!TD_ON_RUNQ(td), ("mi_switch: called by old code"));
#ifdef INVARIANTS
	if (!TD_ON_LOCK(td) && !TD_IS_RUNNING(td))
		mtx_assert(&Giant, MA_NOTOWNED);
#endif
	KASSERT(td->td_critnest == 1 || KERNEL_PANICKED(),
		("mi_switch: switch in a critical section"));
	KASSERT((flags & (SW_INVOL | SW_VOL)) != 0,
	    ("mi_switch: switch must be voluntary or involuntary"));

/*
	 * Don't perform context switches from the debugger.
	 */
	if (kdb_active)
		kdb_switch();
	if (SCHEDULER_STOPPED_TD(td))
		return;
	if (flags & SW_VOL) {
		td->td_ru.ru_nvcsw++;
		td->td_swvoltick = ticks;
	} else {
		td->td_ru.ru_nivcsw++;
		td->td_swinvoltick = ticks;
	}
#ifdef SCHED_STATS
	SCHED_STAT_INC(sched_switch_stats[flags & SW_TYPE_MASK]);
#endif
	/*
	 * Compute the amount of time during which the current
	 * thread was running, and add that to its total so far.
	 */
	new_switchtime = cpu_ticks();
	runtime = new_switchtime - PCPU_GET(switchtime);
	td->td_runtime += runtime;
	td->td_incruntime += runtime;
	PCPU_SET(switchtime, new_switchtime);
	td->td_generation++;	/* bump preempt-detect counter */
	VM_CNT_INC(v_swtch);
	PCPU_SET(switchticks, ticks);
	CTR4(KTR_PROC, "mi_switch: old thread %ld (td_sched %p, pid %ld, %s)",
	    td->td_tid, td_get_sched(td), td->td_proc->p_pid, td->td_name);
#ifdef KDTRACE_HOOKS
	if (SDT_PROBES_ENABLED() &&
	    ((flags & SW_PREEMPT) != 0 || ((flags & SW_INVOL) != 0 &&
	    (flags & SW_TYPE_MASK) == SWT_NEEDRESCHED)))
		SDT_PROBE0(sched, , , preempt);
#endif
	sched_switch(td, flags);
	CTR4(KTR_PROC, "mi_switch: new thread %ld (td_sched %p, pid %ld, %s)",
	    td->td_tid, td_get_sched(td), td->td_proc->p_pid, td->td_name);

/* 
	 * If the last thread was exiting, finish cleaning it up.
	 */
	if ((td = PCPU_GET(deadthread))) {
		PCPU_SET(deadthread, NULL);
		thread_stash(td);
	}
	spinlock_exit();
}

/*
 * Change thread state to be runnable, placing it on the run queue if
 * it is in memory.  If it is swapped out, return true so our caller
 * will know to awaken the swapper.
 *
 * Requires the thread lock on entry, drops on exit.
 */
int
setrunnable(struct thread *td, int srqflags)
{
	int swapin;

THREAD_LOCK_ASSERT(td, MA_OWNED);
	KASSERT(td->td_proc->p_state != PRS_ZOMBIE,
	    ("setrunnable: pid %d is a zombie", td->td_proc->p_pid));

swapin = 0;
	switch (td->td_state) {
	case TDS_RUNNING:
	case TDS_RUNQ:
		break;
	case TDS_CAN_RUN:
		KASSERT((td->td_flags & TDF_INMEM) != 0,
		    ("setrunnable: td %p not in mem, flags 0x%X inhibit 0x%X",
		    td, td->td_flags, td->td_inhibitors));
		/* unlocks thread lock according to flags */
		sched_wakeup(td, srqflags);
		return (0);
	case TDS_INHIBITED:
		/*
		 * If we are only inhibited because we are swapped out
		 * arrange to swap in this process.
		 */
		if (td->td_inhibitors == TDI_SWAPPED &&
		    (td->td_flags & TDF_SWAPINREQ) == 0) {
			td->td_flags |= TDF_SWAPINREQ;
			swapin = 1;
		}
		break;
	default:
		panic("setrunnable: state 0x%x", td->td_state);
	}
	if ((srqflags & (SRQ_HOLD | SRQ_HOLDTD)) == 0)
		thread_unlock(td);

return (swapin);
}

/*
 * Compute a tenex style load average of a quantity on
 * 1, 5 and 15 minute intervals.
 */
static void
loadav(void *arg)
{
	int i, nrun;
	struct loadavg *avg;

nrun = sched_load();
	avg = &averunnable;

for (i = 0; i < 3; i++)
		avg->ldavg[i] = (cexp[i] * avg->ldavg[i] +
		    nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT;

/*
	 * Schedule the next update to occur after 5 seconds, but add a
	 * random variation to avoid synchronisation with processes that
	 * run at regular intervals.
	 */
	callout_reset_sbt(&loadav_callout,
	    SBT_1US * (4000000 + (int)(random() % 2000001)), SBT_1US,
	    loadav, NULL, C_DIRECT_EXEC | C_PREL(32));
}

/* ARGSUSED */
static void
synch_setup(void *dummy)
{
	callout_init(&loadav_callout, 1);

/* Kick off timeout driven events by calling first time. */
	loadav(NULL);
}

int
should_yield(void)
{

return ((u_int)ticks - (u_int)curthread->td_swvoltick >= hogticks);
}

void
maybe_yield(void)
{

if (should_yield())
		kern_yield(PRI_USER);
}

void
kern_yield(int prio)
{
	struct thread *td;

td = curthread;
	DROP_GIANT();
	thread_lock(td);
	if (prio == PRI_USER)
		prio = td->td_user_pri;
	if (prio >= 0)
		sched_prio(td, prio);
	mi_switch(SW_VOL | SWT_RELINQUISH);
	PICKUP_GIANT();
}

/*
 * General purpose yield system call.
 */
int
sys_yield(struct thread *td, struct yield_args *uap)
{

thread_lock(td);
	if (PRI_BASE(td->td_pri_class) == PRI_TIMESHARE)
		sched_prio(td, PRI_MAX_TIMESHARE);
	mi_switch(SW_VOL | SWT_RELINQUISH);
	td->td_retval[0] = 0;
	return (0);
}

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