 @@ -1,1225 +1,1225 @@
-/*	$NetBSD: kern_synch.c,v 1.353 2022/12/05 15:47:14 martin Exp $	*/
+/*	$NetBSD: kern_synch.c,v 1.354 2023/04/09 12:16:42 riastradh Exp $	*/
 /*-
  * Copyright (c) 1999, 2000, 2004, 2006, 2007, 2008, 2009, 2019, 2020
  *    The NetBSD Foundation, Inc.
  * All rights reserved.
+ *
  * This code is derived from software contributed to The NetBSD Foundation
  * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
  * NASA Ames Research Center, by Charles M. Hannum, Andrew Doran and
  * Daniel Sieger.
+ *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
  *    documentation and/or other materials provided with the distribution.
+ *
  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  */
 /*-
  * Copyright (c) 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>
-__KERNEL_RCSID(0, "$NetBSD: kern_synch.c,v 1.353 2022/12/05 15:47:14 martin Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_synch.c,v 1.354 2023/04/09 12:16:42 riastradh Exp $");
 #include "opt_kstack.h"
 #include "opt_dtrace.h"
 #define	__MUTEX_PRIVATE
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/proc.h>
 #include <sys/kernel.h>
 #include <sys/cpu.h>
 #include <sys/pserialize.h>
 #include <sys/resource.h>
 #include <sys/resourcevar.h>
 #include <sys/rwlock.h>
 #include <sys/sched.h>
 #include <sys/syscall_stats.h>
 #include <sys/sleepq.h>
 #include <sys/lockdebug.h>
 #include <sys/evcnt.h>
 #include <sys/intr.h>
 #include <sys/lwpctl.h>
 #include <sys/atomic.h>
 #include <sys/syslog.h>
 #include <uvm/uvm_extern.h>
 #include <dev/lockstat.h>
 #include <sys/dtrace_bsd.h>
 int                             dtrace_vtime_active=0;
 dtrace_vtime_switch_func_t      dtrace_vtime_switch_func;
 static void	sched_unsleep(struct lwp *, bool);
 static void	sched_changepri(struct lwp *, pri_t);
 static void	sched_lendpri(struct lwp *, pri_t);
 syncobj_t sleep_syncobj = {
 	.sobj_flag	= SOBJ_SLEEPQ_SORTED,
 	.sobj_unsleep	= sleepq_unsleep,
 	.sobj_changepri	= sleepq_changepri,
 	.sobj_lendpri	= sleepq_lendpri,
 	.sobj_owner	= syncobj_noowner,
 };
 syncobj_t sched_syncobj = {
 	.sobj_flag	= SOBJ_SLEEPQ_SORTED,
 	.sobj_unsleep	= sched_unsleep,
 	.sobj_changepri	= sched_changepri,
 	.sobj_lendpri	= sched_lendpri,
 	.sobj_owner	= syncobj_noowner,
 };
 syncobj_t kpause_syncobj = {
 	.sobj_flag	= SOBJ_SLEEPQ_NULL,
 	.sobj_unsleep	= sleepq_unsleep,
 	.sobj_changepri	= sleepq_changepri,
 	.sobj_lendpri	= sleepq_lendpri,
 	.sobj_owner	= syncobj_noowner,
 };
 /* "Lightning bolt": once a second sleep address. */
 kcondvar_t		lbolt			__cacheline_aligned;
 u_int			sched_pstats_ticks	__cacheline_aligned;
 /* Preemption event counters. */
 static struct evcnt	kpreempt_ev_crit	__cacheline_aligned;
 static struct evcnt	kpreempt_ev_klock	__cacheline_aligned;
 static struct evcnt	kpreempt_ev_immed	__cacheline_aligned;
 void
 synch_init(void)
+{
 	cv_init(&lbolt, "lbolt");
 	evcnt_attach_dynamic(&kpreempt_ev_crit, EVCNT_TYPE_MISC, NULL,
 	   "kpreempt", "defer: critical section");
 	evcnt_attach_dynamic(&kpreempt_ev_klock, EVCNT_TYPE_MISC, NULL,
 	   "kpreempt", "defer: kernel_lock");
 	evcnt_attach_dynamic(&kpreempt_ev_immed, EVCNT_TYPE_MISC, NULL,
 	   "kpreempt", "immediate");
+}
 /*
  * OBSOLETE INTERFACE
+ *
  * General sleep call.  Suspends the current LWP until a wakeup is
  * performed on the specified identifier.  The LWP will then be made
  * runnable with the specified priority.  Sleeps at most timo/hz seconds (0
  * means no timeout).  If pri includes PCATCH flag, signals are checked
  * before and after sleeping, else signals are not checked.  Returns 0 if
  * awakened, EWOULDBLOCK if the timeout expires.  If PCATCH is set and a
  * signal needs to be delivered, 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).
  */
 int
 tsleep(wchan_t ident, pri_t priority, const char *wmesg, int timo)
+{
 	struct lwp *l = curlwp;
 	sleepq_t *sq;
 	kmutex_t *mp;
 	bool catch_p;
 	KASSERT((l->l_pflag & LP_INTR) == 0);
 	KASSERT(ident != &lbolt);
 	if (sleepq_dontsleep(l)) {
 		(void)sleepq_abort(NULL, 0);
 		return 0;
+	}
 	l->l_kpriority = true;
 	catch_p = priority & PCATCH;
 	sq = sleeptab_lookup(&sleeptab, ident, &mp);
 	sleepq_enter(sq, l, mp);
 	sleepq_enqueue(sq, ident, wmesg, &sleep_syncobj, catch_p);
 	return sleepq_block(timo, catch_p, &sleep_syncobj);
+}
 int
 mtsleep(wchan_t ident, pri_t priority, const char *wmesg, int timo,
 	kmutex_t *mtx)
+{
 	struct lwp *l = curlwp;
 	sleepq_t *sq;
 	kmutex_t *mp;
 	bool catch_p;
 	int error;
 	KASSERT((l->l_pflag & LP_INTR) == 0);
 	KASSERT(ident != &lbolt);
 	if (sleepq_dontsleep(l)) {
 		(void)sleepq_abort(mtx, (priority & PNORELOCK) != 0);
 		return 0;
+	}
 	l->l_kpriority = true;
 	catch_p = priority & PCATCH;
 	sq = sleeptab_lookup(&sleeptab, ident, &mp);
 	sleepq_enter(sq, l, mp);
 	sleepq_enqueue(sq, ident, wmesg, &sleep_syncobj, catch_p);
 	mutex_exit(mtx);
 	error = sleepq_block(timo, catch_p, &sleep_syncobj);
 	if ((priority & PNORELOCK) == 0)
 		mutex_enter(mtx);
 	return error;
+}
 /*
  * General sleep call for situations where a wake-up is not expected.
  */
 int
 kpause(const char *wmesg, bool intr, int timo, kmutex_t *mtx)
+{
 	struct lwp *l = curlwp;
 	int error;
-	KASSERT(!(timo == 0 && intr == false));
+	KASSERT(timo != 0 || intr);
 	if (sleepq_dontsleep(l))
 		return sleepq_abort(NULL, 0);
 	if (mtx != NULL)
 		mutex_exit(mtx);
 	l->l_kpriority = true;
 	lwp_lock(l);
 	KERNEL_UNLOCK_ALL(NULL, &l->l_biglocks);
 	sleepq_enqueue(NULL, l, wmesg, &kpause_syncobj, intr);
 	error = sleepq_block(timo, intr, &kpause_syncobj);
 	if (mtx != NULL)
 		mutex_enter(mtx);
 	return error;
+}
 /*
  * OBSOLETE INTERFACE
+ *
  * Make all LWPs sleeping on the specified identifier runnable.
  */
 void
 wakeup(wchan_t ident)
+{
 	sleepq_t *sq;
 	kmutex_t *mp;
 	if (__predict_false(cold))
 		return;
 	sq = sleeptab_lookup(&sleeptab, ident, &mp);
 	sleepq_wake(sq, ident, (u_int)-1, mp);
+}
 /*
  * General yield call.  Puts the current LWP back on its run queue and
  * performs a context switch.
  */
 void
 yield(void)
+{
 	struct lwp *l = curlwp;
 	KERNEL_UNLOCK_ALL(l, &l->l_biglocks);
 	lwp_lock(l);
 	KASSERT(lwp_locked(l, l->l_cpu->ci_schedstate.spc_lwplock));
 	KASSERT(l->l_stat == LSONPROC);
 	/* Voluntary - ditch kpriority boost. */
 	l->l_kpriority = false;
 	spc_lock(l->l_cpu);
 	mi_switch(l);
 	KERNEL_LOCK(l->l_biglocks, l);
+}
 /*
  * General preemption call.  Puts the current LWP back on its run queue
  * and performs an involuntary context switch.  Different from yield()
  * in that:
+ *
  * - It's counted differently (involuntary vs. voluntary).
  * - Realtime threads go to the head of their runqueue vs. tail for yield().
  * - Priority boost is retained unless LWP has exceeded timeslice.
  */
 void
 preempt(void)
+{
 	struct lwp *l = curlwp;
 	KERNEL_UNLOCK_ALL(l, &l->l_biglocks);
 	lwp_lock(l);
 	KASSERT(lwp_locked(l, l->l_cpu->ci_schedstate.spc_lwplock));
 	KASSERT(l->l_stat == LSONPROC);
 	spc_lock(l->l_cpu);
 	/* Involuntary - keep kpriority boost unless a CPU hog. */
 	if ((l->l_cpu->ci_schedstate.spc_flags & SPCF_SHOULDYIELD) != 0) {
 		l->l_kpriority = false;
+	}
 	l->l_pflag |= LP_PREEMPTING;
 	mi_switch(l);
 	KERNEL_LOCK(l->l_biglocks, l);
+}
 /*
  * Return true if the current LWP should yield the processor.  Intended to
  * be used by long-running code in kernel.
  */
 inline bool
 preempt_needed(void)
+{
 	lwp_t *l = curlwp;
 	int needed;
 	KPREEMPT_DISABLE(l);
 	needed = l->l_cpu->ci_want_resched;
 	KPREEMPT_ENABLE(l);
 	return (needed != 0);
+}
 /*
  * A breathing point for long running code in kernel.
  */
 void
 preempt_point(void)
+{
 	if (__predict_false(preempt_needed())) {
 		preempt();
+	}
+}
 /*
  * Handle a request made by another agent to preempt the current LWP
  * in-kernel.  Usually called when l_dopreempt may be non-zero.
+ *
  * Character addresses for lockstat only.
  */
 static char	kpreempt_is_disabled;
 static char	kernel_lock_held;
 static char	is_softint_lwp;
 static char	spl_is_raised;
 bool
 kpreempt(uintptr_t where)
+{
 	uintptr_t failed;
 	lwp_t *l;
 	int s, dop, lsflag;
 	l = curlwp;
 	failed = 0;
 	while ((dop = l->l_dopreempt) != 0) {
 		if (l->l_stat != LSONPROC) {
 			/*
 			 * About to block (or die), let it happen.
 			 * Doesn't really count as "preemption has
 			 * been blocked", since we're going to
 			 * context switch.
 			 */
 			atomic_swap_uint(&l->l_dopreempt, 0);
 			return true;
+		}
 		KASSERT((l->l_flag & LW_IDLE) == 0);
 		if (__predict_false(l->l_nopreempt != 0)) {
 			/* LWP holds preemption disabled, explicitly. */
 			if ((dop & DOPREEMPT_COUNTED) == 0) {
 				kpreempt_ev_crit.ev_count++;
+			}
 			failed = (uintptr_t)&kpreempt_is_disabled;
 			break;
+		}
 		if (__predict_false((l->l_pflag & LP_INTR) != 0)) {
 			/* Can't preempt soft interrupts yet. */
 			atomic_swap_uint(&l->l_dopreempt, 0);
 			failed = (uintptr_t)&is_softint_lwp;
 			break;
+		}
 		s = splsched();
 		if (__predict_false(l->l_blcnt != 0 ||
 		    curcpu()->ci_biglock_wanted != NULL)) {
 			/* Hold or want kernel_lock, code is not MT safe. */
 			splx(s);
 			if ((dop & DOPREEMPT_COUNTED) == 0) {
 				kpreempt_ev_klock.ev_count++;
+			}
 			failed = (uintptr_t)&kernel_lock_held;
 			break;
+		}
 		if (__predict_false(!cpu_kpreempt_enter(where, s))) {
 			/*
 			 * It may be that the IPL is too high.
 			 * kpreempt_enter() can schedule an
 			 * interrupt to retry later.
 			 */
 			splx(s);
 			failed = (uintptr_t)&spl_is_raised;
 			break;
+		}
 		/* Do it! */
 		if (__predict_true((dop & DOPREEMPT_COUNTED) == 0)) {
 			kpreempt_ev_immed.ev_count++;
+		}
 		lwp_lock(l);
 		/* Involuntary - keep kpriority boost. */
 		l->l_pflag |= LP_PREEMPTING;
 		spc_lock(l->l_cpu);
 		mi_switch(l);
 		l->l_nopreempt++;
 		splx(s);
 		/* Take care of any MD cleanup. */
 		cpu_kpreempt_exit(where);
 		l->l_nopreempt--;
+	}
 	if (__predict_true(!failed)) {
 		return false;
+	}
 	/* Record preemption failure for reporting via lockstat. */
 	atomic_or_uint(&l->l_dopreempt, DOPREEMPT_COUNTED);
 	lsflag = 0;
 	LOCKSTAT_ENTER(lsflag);
 	if (__predict_false(lsflag)) {
 		if (where == 0) {
 			where = (uintptr_t)__builtin_return_address(0);
+		}
 		/* Preemption is on, might recurse, so make it atomic. */
 		if (atomic_cas_ptr_ni((void *)&l->l_pfailaddr, NULL,
 		    (void *)where) == NULL) {
 			LOCKSTAT_START_TIMER(lsflag, l->l_pfailtime);
 			l->l_pfaillock = failed;
+		}
+	}
 	LOCKSTAT_EXIT(lsflag);
 	return true;
+}
 /*
  * Return true if preemption is explicitly disabled.
  */
 bool
 kpreempt_disabled(void)
+{
 	const lwp_t *l = curlwp;
 	return l->l_nopreempt != 0 || l->l_stat == LSZOMB ||
 	    (l->l_flag & LW_IDLE) != 0 || (l->l_pflag & LP_INTR) != 0 ||
 	    cpu_kpreempt_disabled();
+}
 /*
  * Disable kernel preemption.
  */
 void
 kpreempt_disable(void)
+{
 	KPREEMPT_DISABLE(curlwp);
+}
 /*
  * Reenable kernel preemption.
  */
 void
 kpreempt_enable(void)
+{
 	KPREEMPT_ENABLE(curlwp);
+}
 /*
  * Compute the amount of time during which the current lwp was running.
+ *
  * - update l_rtime unless it's an idle lwp.
  */
 void
 updatertime(lwp_t *l, const struct bintime *now)
+{
 	if (__predict_false(l->l_flag & LW_IDLE))
 		return;
 	/* rtime += now - stime */
 	bintime_add(&l->l_rtime, now);
 	bintime_sub(&l->l_rtime, &l->l_stime);
+}
 /*
  * Select next LWP from the current CPU to run..
  */
 static inline lwp_t *
 nextlwp(struct cpu_info *ci, struct schedstate_percpu *spc)
+{
 	lwp_t *newl;
 	/*
 	 * Let sched_nextlwp() select the LWP to run the CPU next.
 	 * If no LWP is runnable, select the idle LWP.
+	 *
 	 * On arrival here LWPs on a run queue are locked by spc_mutex which
 	 * is currently held.  Idle LWPs are always locked by spc_lwplock,
 	 * which may or may not be held here.  On exit from this code block,
 	 * in all cases newl is locked by spc_lwplock.
 	 */
 	newl = sched_nextlwp();
 	if (newl != NULL) {
 		sched_dequeue(newl);
 		KASSERT(lwp_locked(newl, spc->spc_mutex));
 		KASSERT(newl->l_cpu == ci);
 		newl->l_stat = LSONPROC;
 		newl->l_pflag |= LP_RUNNING;
 		spc->spc_curpriority = lwp_eprio(newl);
 		spc->spc_flags &= ~(SPCF_SWITCHCLEAR | SPCF_IDLE);
 		lwp_setlock(newl, spc->spc_lwplock);
 	} else {
 		/*
 		 * The idle LWP does not get set to LSONPROC, because
 		 * otherwise it screws up the output from top(1) etc.
 		 */
 		newl = ci->ci_data.cpu_idlelwp;
 		newl->l_pflag |= LP_RUNNING;
 		spc->spc_curpriority = PRI_IDLE;
 		spc->spc_flags = (spc->spc_flags & ~SPCF_SWITCHCLEAR) |
 		    SPCF_IDLE;
+	}
 	/*
 	 * Only clear want_resched if there are no pending (slow) software
 	 * interrupts.  We can do this without an atomic, because no new
 	 * LWPs can appear in the queue due to our hold on spc_mutex, and
 	 * the update to ci_want_resched will become globally visible before
 	 * the release of spc_mutex becomes globally visible.
 	 */
 	if (ci->ci_data.cpu_softints == 0)
 		ci->ci_want_resched = 0;
 	return newl;
+}
 /*
  * The machine independent parts of context switch.
+ *
  * NOTE: l->l_cpu is not changed in this routine, because an LWP never
  * changes its own l_cpu (that would screw up curcpu on many ports and could
  * cause all kinds of other evil stuff).  l_cpu is always changed by some
  * other actor, when it's known the LWP is not running (the LP_RUNNING flag
  * is checked under lock).
  */
 void
 mi_switch(lwp_t *l)
+{
 	struct cpu_info *ci;
 	struct schedstate_percpu *spc;
 	struct lwp *newl;
 	kmutex_t *lock;
 	int oldspl;
 	struct bintime bt;
 	bool returning;
 	KASSERT(lwp_locked(l, NULL));
 	KASSERT(kpreempt_disabled());
 	KASSERT(mutex_owned(curcpu()->ci_schedstate.spc_mutex));
 	KASSERTMSG(l->l_blcnt == 0, "kernel_lock leaked");
 	kstack_check_magic(l);
 	binuptime(&bt);
 	KASSERTMSG(l == curlwp, "l %p curlwp %p", l, curlwp);
 	KASSERT((l->l_pflag & LP_RUNNING) != 0);
 	KASSERT(l->l_cpu == curcpu() || l->l_stat == LSRUN);
 	ci = curcpu();
 	spc = &ci->ci_schedstate;
 	returning = false;
 	newl = NULL;
 	/*
 	 * If we have been asked to switch to a specific LWP, then there
 	 * is no need to inspect the run queues.  If a soft interrupt is
 	 * blocking, then return to the interrupted thread without adjusting
 	 * VM context or its start time: neither have been changed in order
 	 * to take the interrupt.
 	 */
 	if (l->l_switchto != NULL) {
 		if ((l->l_pflag & LP_INTR) != 0) {
 			returning = true;
 			softint_block(l);
 			if ((l->l_pflag & LP_TIMEINTR) != 0)
 				updatertime(l, &bt);
+		}
 		newl = l->l_switchto;
 		l->l_switchto = NULL;
+	}
 #ifndef __HAVE_FAST_SOFTINTS
 	else if (ci->ci_data.cpu_softints != 0) {
 		/* There are pending soft interrupts, so pick one. */
 		newl = softint_picklwp();
 		newl->l_stat = LSONPROC;
 		newl->l_pflag |= LP_RUNNING;
+	}
 #endif	/* !__HAVE_FAST_SOFTINTS */
 	/*
 	 * If on the CPU and we have gotten this far, then we must yield.
 	 */
 	if (l->l_stat == LSONPROC && l != newl) {
 		KASSERT(lwp_locked(l, spc->spc_lwplock));
 		KASSERT((l->l_flag & LW_IDLE) == 0);
 		l->l_stat = LSRUN;
 		lwp_setlock(l, spc->spc_mutex);
 		sched_enqueue(l);
 		sched_preempted(l);
 		/*
 		 * Handle migration.  Note that "migrating LWP" may
 		 * be reset here, if interrupt/preemption happens
 		 * early in idle LWP.
 		 */
 		if (l->l_target_cpu != NULL && (l->l_pflag & LP_BOUND) == 0) {
 			KASSERT((l->l_pflag & LP_INTR) == 0);
 			spc->spc_migrating = l;
+		}
+	}
 	/* Pick new LWP to run. */
 	if (newl == NULL) {
 		newl = nextlwp(ci, spc);
+	}
 	/* Items that must be updated with the CPU locked. */
 	if (!returning) {
 		/* Count time spent in current system call */
 		SYSCALL_TIME_SLEEP(l);
 		updatertime(l, &bt);
 		/* Update the new LWP's start time. */
 		newl->l_stime = bt;
 		/*
 		 * ci_curlwp changes when a fast soft interrupt occurs.
 		 * We use ci_onproc to keep track of which kernel or
 		 * user thread is running 'underneath' the software
 		 * interrupt.  This is important for time accounting,
 		 * itimers and forcing user threads to preempt (aston).
 		 */
 		ci->ci_onproc = newl;
+	}
 	/*
 	 * Preemption related tasks.  Must be done holding spc_mutex.  Clear
 	 * l_dopreempt without an atomic - it's only ever set non-zero by
 	 * sched_resched_cpu() which also holds spc_mutex, and only ever
 	 * cleared by the LWP itself (us) with atomics when not under lock.
 	 */
 	l->l_dopreempt = 0;
 	if (__predict_false(l->l_pfailaddr != 0)) {
 		LOCKSTAT_FLAG(lsflag);
 		LOCKSTAT_ENTER(lsflag);
 		LOCKSTAT_STOP_TIMER(lsflag, l->l_pfailtime);
 		LOCKSTAT_EVENT_RA(lsflag, l->l_pfaillock, LB_NOPREEMPT|LB_SPIN,
 , l->l_pfailtime, l->l_pfailaddr);
 		LOCKSTAT_EXIT(lsflag);
 		l->l_pfailtime = 0;
 		l->l_pfaillock = 0;
 		l->l_pfailaddr = 0;
+	}
 	if (l != newl) {
 		struct lwp *prevlwp;
 		/* Release all locks, but leave the current LWP locked */
 		if (l->l_mutex == spc->spc_mutex) {
 			/*
 			 * Drop spc_lwplock, if the current LWP has been moved
 			 * to the run queue (it is now locked by spc_mutex).
 			 */
 			mutex_spin_exit(spc->spc_lwplock);
 		} else {
 			/*
 			 * Otherwise, drop the spc_mutex, we are done with the
 			 * run queues.
 			 */
 			mutex_spin_exit(spc->spc_mutex);
+		}
 		/* We're down to only one lock, so do debug checks. */
 		LOCKDEBUG_BARRIER(l->l_mutex, 1);
 		/* Count the context switch. */
 		CPU_COUNT(CPU_COUNT_NSWTCH, 1);
 		l->l_ncsw++;
 		if ((l->l_pflag & LP_PREEMPTING) != 0) {
 			l->l_nivcsw++;
 			l->l_pflag &= ~LP_PREEMPTING;
+		}
 		/*
 		 * Increase the count of spin-mutexes before the release
 		 * of the last lock - we must remain at IPL_SCHED after
 		 * releasing the lock.
 		 */
 		KASSERTMSG(ci->ci_mtx_count == -1,
 		    "%s: cpu%u: ci_mtx_count (%d) != -1 "
 		    "(block with spin-mutex held)",
 		     __func__, cpu_index(ci), ci->ci_mtx_count);
 		oldspl = MUTEX_SPIN_OLDSPL(ci);
 		ci->ci_mtx_count = -2;
 		/* Update status for lwpctl, if present. */
 		if (l->l_lwpctl != NULL) {
 			l->l_lwpctl->lc_curcpu = (l->l_stat == LSZOMB ?
 			    LWPCTL_CPU_EXITED : LWPCTL_CPU_NONE);
+		}
 		/*
 		 * If curlwp is a soft interrupt LWP, there's nobody on the
 		 * other side to unlock - we're returning into an assembly
 		 * trampoline.  Unlock now.  This is safe because this is a
 		 * kernel LWP and is bound to current CPU: the worst anyone
 		 * else will do to it, is to put it back onto this CPU's run
 		 * queue (and the CPU is busy here right now!).
 		 */
 		if (returning) {
 			/* Keep IPL_SCHED after this; MD code will fix up. */
 			l->l_pflag &= ~LP_RUNNING;
 			lwp_unlock(l);
 		} else {
 			/* A normal LWP: save old VM context. */
 			pmap_deactivate(l);
+		}
 		/*
 		 * If DTrace has set the active vtime enum to anything
 		 * other than INACTIVE (0), then it should have set the
 		 * function to call.
 		 */
 		if (__predict_false(dtrace_vtime_active)) {
 			(*dtrace_vtime_switch_func)(newl);
+		}
 		/*
 		 * We must ensure not to come here from inside a read section.
 		 */
 		KASSERT(pserialize_not_in_read_section());
 		/* Switch to the new LWP.. */
 #ifdef MULTIPROCESSOR
 		KASSERT(curlwp == ci->ci_curlwp);
 #endif
 		KASSERTMSG(l == curlwp, "l %p curlwp %p", l, curlwp);
 		prevlwp = cpu_switchto(l, newl, returning);
 		ci = curcpu();
 #ifdef MULTIPROCESSOR
 		KASSERT(curlwp == ci->ci_curlwp);
 #endif
 		KASSERTMSG(l == curlwp, "l %p curlwp %p prevlwp %p",
 		    l, curlwp, prevlwp);
 		KASSERT(prevlwp != NULL);
 		KASSERT(l->l_cpu == ci);
 		KASSERT(ci->ci_mtx_count == -2);
 		/*
 		 * Immediately mark the previous LWP as no longer running
 		 * and unlock (to keep lock wait times short as possible).
 		 * We'll still be at IPL_SCHED afterwards.  If a zombie,
 		 * don't touch after clearing LP_RUNNING as it could be
 		 * reaped by another CPU.  Issue a memory barrier to ensure
 		 * this.
+		 *
 		 * atomic_store_release matches atomic_load_acquire in
 		 * lwp_free.
 		 */
 		KASSERT((prevlwp->l_pflag & LP_RUNNING) != 0);
 		lock = prevlwp->l_mutex;
 		if (__predict_false(prevlwp->l_stat == LSZOMB)) {
 			atomic_store_release(&prevlwp->l_pflag,
 			    prevlwp->l_pflag & ~LP_RUNNING);
 		} else {
 			prevlwp->l_pflag &= ~LP_RUNNING;
+		}
 		mutex_spin_exit(lock);
 		/*
 		 * Switched away - we have new curlwp.
 		 * Restore VM context and IPL.
 		 */
 		pmap_activate(l);
 		pcu_switchpoint(l);
 		/* Update status for lwpctl, if present. */
 		if (l->l_lwpctl != NULL) {
 			l->l_lwpctl->lc_curcpu = (int)cpu_index(ci);
 			l->l_lwpctl->lc_pctr++;
+		}
 		/*
 		 * Normalize the spin mutex count and restore the previous
 		 * SPL.  Note that, unless the caller disabled preemption,
 		 * we can be preempted at any time after this splx().
 		 */
 		KASSERT(l->l_cpu == ci);
 		KASSERT(ci->ci_mtx_count == -1);
 		ci->ci_mtx_count = 0;
 		splx(oldspl);
 	} else {
 		/* Nothing to do - just unlock and return. */
 		mutex_spin_exit(spc->spc_mutex);
 		l->l_pflag &= ~LP_PREEMPTING;
 		lwp_unlock(l);
+	}
 	KASSERT(l == curlwp);
 	KASSERT(l->l_stat == LSONPROC || (l->l_flag & LW_IDLE) != 0);
 	SYSCALL_TIME_WAKEUP(l);
 	LOCKDEBUG_BARRIER(NULL, 1);
+}
 /*
  * setrunnable: change LWP state to be runnable, placing it on the run queue.
+ *
  * Call with the process and LWP locked.  Will return with the LWP unlocked.
  */
 void
 setrunnable(struct lwp *l)
+{
 	struct proc *p = l->l_proc;
 	struct cpu_info *ci;
 	kmutex_t *oldlock;
 	KASSERT((l->l_flag & LW_IDLE) == 0);
 	KASSERT((l->l_flag & LW_DBGSUSPEND) == 0);
 	KASSERT(mutex_owned(p->p_lock));
 	KASSERT(lwp_locked(l, NULL));
 	KASSERT(l->l_mutex != l->l_cpu->ci_schedstate.spc_mutex);
 	switch (l->l_stat) {
 	case LSSTOP:
 		/*
 		 * If we're being traced (possibly because someone attached us
 		 * while we were stopped), check for a signal from the debugger.
 		 */
 		if ((p->p_slflag & PSL_TRACED) != 0 && p->p_xsig != 0)
 			signotify(l);
 		p->p_nrlwps++;
 		break;
 	case LSSUSPENDED:
 		KASSERT(lwp_locked(l, l->l_cpu->ci_schedstate.spc_lwplock));
 		l->l_flag &= ~LW_WSUSPEND;
 		p->p_nrlwps++;
 		cv_broadcast(&p->p_lwpcv);
 		break;
 	case LSSLEEP:
 		KASSERT(l->l_wchan != NULL);
 		break;
 	case LSIDL:
 		KASSERT(lwp_locked(l, l->l_cpu->ci_schedstate.spc_lwplock));
 		break;
 	default:
 		panic("setrunnable: lwp %p state was %d", l, l->l_stat);
+	}
 	/*
 	 * If the LWP was sleeping, start it again.
 	 */
 	if (l->l_wchan != NULL) {
 		l->l_stat = LSSLEEP;
 		/* lwp_unsleep() will release the lock. */
 		lwp_unsleep(l, true);
 		return;
+	}
 	/*
 	 * If the LWP is still on the CPU, mark it as LSONPROC.  It may be
 	 * about to call mi_switch(), in which case it will yield.
 	 */
 	if ((l->l_pflag & LP_RUNNING) != 0) {
 		l->l_stat = LSONPROC;
 		l->l_slptime = 0;
 		lwp_unlock(l);
 		return;
+	}
 	/*
 	 * Look for a CPU to run.
 	 * Set the LWP runnable.
 	 */
 	ci = sched_takecpu(l);
 	l->l_cpu = ci;
 	spc_lock(ci);
 	oldlock = lwp_setlock(l, l->l_cpu->ci_schedstate.spc_mutex);
 	sched_setrunnable(l);
 	l->l_stat = LSRUN;
 	l->l_slptime = 0;
 	sched_enqueue(l);
 	sched_resched_lwp(l, true);
 	/* SPC & LWP now unlocked. */
 	mutex_spin_exit(oldlock);
+}
 /*
  * suspendsched:
+ *
  *	Convert all non-LW_SYSTEM LSSLEEP or LSRUN LWPs to LSSUSPENDED.
  */
 void
 suspendsched(void)
+{
 	CPU_INFO_ITERATOR cii;
 	struct cpu_info *ci;
 	struct lwp *l;
 	struct proc *p;
 	/*
 	 * We do this by process in order not to violate the locking rules.
 	 */
 	mutex_enter(&proc_lock);
 	PROCLIST_FOREACH(p, &allproc) {
 		mutex_enter(p->p_lock);
 		if ((p->p_flag & PK_SYSTEM) != 0) {
 			mutex_exit(p->p_lock);
 			continue;
+		}
 		if (p->p_stat != SSTOP) {
 			if (p->p_stat != SZOMB && p->p_stat != SDEAD) {
 				p->p_pptr->p_nstopchild++;
 				p->p_waited = 0;
+			}
 			p->p_stat = SSTOP;
+		}
 		LIST_FOREACH(l, &p->p_lwps, l_sibling) {
 			if (l == curlwp)
 				continue;
 			lwp_lock(l);
 			/*
 			 * Set L_WREBOOT so that the LWP will suspend itself
 			 * when it tries to return to user mode.  We want to
 			 * try and get to get as many LWPs as possible to
 			 * the user / kernel boundary, so that they will
 			 * release any locks that they hold.
 			 */
 			l->l_flag |= (LW_WREBOOT | LW_WSUSPEND);
 			if (l->l_stat == LSSLEEP &&
 			    (l->l_flag & LW_SINTR) != 0) {
 				/* setrunnable() will release the lock. */
 				setrunnable(l);
 				continue;
+			}
 			lwp_unlock(l);
+		}
 		mutex_exit(p->p_lock);
+	}
 	mutex_exit(&proc_lock);
 	/*
 	 * Kick all CPUs to make them preempt any LWPs running in user mode.
 	 * They'll trap into the kernel and suspend themselves in userret().
+	 *
 	 * Unusually, we don't hold any other scheduler object locked, which
 	 * would keep preemption off for sched_resched_cpu(), so disable it
 	 * explicitly.
 	 */
 	kpreempt_disable();
 	for (CPU_INFO_FOREACH(cii, ci)) {
 		spc_lock(ci);
 		sched_resched_cpu(ci, PRI_KERNEL, true);
 		/* spc now unlocked */
+	}
 	kpreempt_enable();
+}
 /*
  * sched_unsleep:
+ *
  *	The is called when the LWP has not been awoken normally but instead
  *	interrupted: for example, if the sleep timed out.  Because of this,
  *	it's not a valid action for running or idle LWPs.
  */
 static void
 sched_unsleep(struct lwp *l, bool cleanup)
+{
 	lwp_unlock(l);
 	panic("sched_unsleep");
+}
 static void
 sched_changepri(struct lwp *l, pri_t pri)
+{
 	struct schedstate_percpu *spc;
 	struct cpu_info *ci;
 	KASSERT(lwp_locked(l, NULL));
 	ci = l->l_cpu;
 	spc = &ci->ci_schedstate;
 	if (l->l_stat == LSRUN) {
 		KASSERT(lwp_locked(l, spc->spc_mutex));
 		sched_dequeue(l);
 		l->l_priority = pri;
 		sched_enqueue(l);
 		sched_resched_lwp(l, false);
 	} else if (l->l_stat == LSONPROC && l->l_class != SCHED_OTHER) {
 		/* On priority drop, only evict realtime LWPs. */
 		KASSERT(lwp_locked(l, spc->spc_lwplock));
 		l->l_priority = pri;
 		spc_lock(ci);
 		sched_resched_cpu(ci, spc->spc_maxpriority, true);
 		/* spc now unlocked */
 	} else {
 		l->l_priority = pri;
+	}
+}
 static void
 sched_lendpri(struct lwp *l, pri_t pri)
+{
 	struct schedstate_percpu *spc;
 	struct cpu_info *ci;
 	KASSERT(lwp_locked(l, NULL));
 	ci = l->l_cpu;
 	spc = &ci->ci_schedstate;
 	if (l->l_stat == LSRUN) {
 		KASSERT(lwp_locked(l, spc->spc_mutex));
 		sched_dequeue(l);
 		l->l_inheritedprio = pri;
 		l->l_auxprio = MAX(l->l_inheritedprio, l->l_protectprio);
 		sched_enqueue(l);
 		sched_resched_lwp(l, false);
 	} else if (l->l_stat == LSONPROC && l->l_class != SCHED_OTHER) {
 		/* On priority drop, only evict realtime LWPs. */
 		KASSERT(lwp_locked(l, spc->spc_lwplock));
 		l->l_inheritedprio = pri;
 		l->l_auxprio = MAX(l->l_inheritedprio, l->l_protectprio);
 		spc_lock(ci);
 		sched_resched_cpu(ci, spc->spc_maxpriority, true);
 		/* spc now unlocked */
 	} else {
 		l->l_inheritedprio = pri;
 		l->l_auxprio = MAX(l->l_inheritedprio, l->l_protectprio);
+	}
+}
 struct lwp *
 syncobj_noowner(wchan_t wchan)
+{
 	return NULL;
+}
 /* Decay 95% of proc::p_pctcpu in 60 seconds, ccpu = exp(-1/20) */
 const fixpt_t ccpu = 0.95122942450071400909 * FSCALE;
 /*
  * Constants for averages over 1, 5 and 15 minutes when sampling at
  * 5 second intervals.
  */
 static const fixpt_t cexp[ ] = {
 .9200444146293232 * FSCALE,	/* exp(-1/12) */
 .9834714538216174 * FSCALE,	/* exp(-1/60) */
 .9944598480048967 * FSCALE,	/* exp(-1/180) */
 };
 /*
  * sched_pstats:
+ *
  * => Update process statistics and check CPU resource allocation.
  * => Call scheduler-specific hook to eventually adjust LWP priorities.
  * => Compute load average of a quantity on 1, 5 and 15 minute intervals.
  */
 void
 sched_pstats(void)
+{
 	struct loadavg *avg = &averunnable;
 	const int clkhz = (stathz != 0 ? stathz : hz);
 	static bool backwards = false;
 	static u_int lavg_count = 0;
 	struct proc *p;
 	int nrun;
 	sched_pstats_ticks++;
 	if (++lavg_count >= 5) {
 		lavg_count = 0;
 		nrun = 0;
+	}
 	mutex_enter(&proc_lock);
 	PROCLIST_FOREACH(p, &allproc) {
 		struct lwp *l;
 		struct rlimit *rlim;
 		time_t runtm;
 		int sig;
 		/* Increment sleep time (if sleeping), ignore overflow. */
 		mutex_enter(p->p_lock);
 		runtm = p->p_rtime.sec;
 		LIST_FOREACH(l, &p->p_lwps, l_sibling) {
 			fixpt_t lpctcpu;
 			u_int lcpticks;
 			if (__predict_false((l->l_flag & LW_IDLE) != 0))
 				continue;
 			lwp_lock(l);
 			runtm += l->l_rtime.sec;
 			l->l_swtime++;
 			sched_lwp_stats(l);
 			/* For load average calculation. */
 			if (__predict_false(lavg_count == 0) &&
 			    (l->l_flag & (LW_SINTR | LW_SYSTEM)) == 0) {
 				switch (l->l_stat) {
 				case LSSLEEP:
 					if (l->l_slptime > 1) {
 						break;
+					}
 					/* FALLTHROUGH */
 				case LSRUN:
 				case LSONPROC:
 				case LSIDL:
 					nrun++;
+				}
+			}
 			lwp_unlock(l);
 			l->l_pctcpu = (l->l_pctcpu * ccpu) >> FSHIFT;
 			if (l->l_slptime != 0)
 				continue;
 			lpctcpu = l->l_pctcpu;
 			lcpticks = atomic_swap_uint(&l->l_cpticks, 0);
 			lpctcpu += ((FSCALE - ccpu) *
 			    (lcpticks * FSCALE / clkhz)) >> FSHIFT;
 			l->l_pctcpu = lpctcpu;
+		}
 		/* Calculating p_pctcpu only for ps(1) */
 		p->p_pctcpu = (p->p_pctcpu * ccpu) >> FSHIFT;
 		if (__predict_false(runtm < 0)) {
 			if (!backwards) {
 				backwards = true;
 				printf("WARNING: negative runtime; "
 				    "monotonic clock has gone backwards\n");
+			}
 			mutex_exit(p->p_lock);
 			continue;
+		}
 		/*
 		 * Check if the process exceeds its CPU resource allocation.
 		 * If over the hard limit, kill it with SIGKILL.
 		 * If over the soft limit, send SIGXCPU and raise
 		 * the soft limit a little.
 		 */
 		rlim = &p->p_rlimit[RLIMIT_CPU];
 		sig = 0;
 		if (__predict_false(runtm >= rlim->rlim_cur)) {
 			if (runtm >= rlim->rlim_max) {
 				sig = SIGKILL;
 				log(LOG_NOTICE,
 				    "pid %d, command %s, is killed: %s\n",
 				    p->p_pid, p->p_comm, "exceeded RLIMIT_CPU");
 				uprintf("pid %d, command %s, is killed: %s\n",
 				    p->p_pid, p->p_comm, "exceeded RLIMIT_CPU");
 			} else {
 				sig = SIGXCPU;
 				if (rlim->rlim_cur < rlim->rlim_max)
 					rlim->rlim_cur += 5;
+			}
+		}
 		mutex_exit(p->p_lock);
 		if (__predict_false(sig)) {
 			KASSERT((p->p_flag & PK_SYSTEM) == 0);
 			psignal(p, sig);
+		}
+	}
 	/* Load average calculation. */
 	if (__predict_false(lavg_count == 0)) {
 		int i;
 		CTASSERT(__arraycount(cexp) == __arraycount(avg->ldavg));
 		for (i = 0; i < __arraycount(cexp); i++) {
 			avg->ldavg[i] = (cexp[i] * avg->ldavg[i] +
 			    nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT;
+		}
+	}
 	/* Lightning bolt. */
 	cv_broadcast(&lbolt);
 	mutex_exit(&proc_lock);
+}