Index: sys/fs/procfs/procfs_ioctl.c
===================================================================
--- sys/fs/procfs/procfs_ioctl.c
+++ sys/fs/procfs/procfs_ioctl.c
@@ -65,7 +65,7 @@
 #ifdef COMPAT_FREEBSD32
 	struct procfs_status32 *ps32;
 #endif
-	int error, flags, sig;
+	int error, flags;
 #ifdef COMPAT_FREEBSD6
 	int ival;
 #endif
@@ -85,7 +85,7 @@
 		data = &ival;
 #endif
 	case PIOCBIS:
-		p->p_stops |= *(unsigned int *)data;
+		error = EOPNOTSUPP;
 		break;
 #if defined(COMPAT_FREEBSD5) || defined(COMPAT_FREEBSD4) || defined(COMPAT_43)
 	case _IOC(IOC_IN, 'p', 2, 0):
@@ -96,7 +96,7 @@
 		data = &ival;
 #endif
 	case PIOCBIC:
-		p->p_stops &= ~*(unsigned int *)data;
+		error = EOPNOTSUPP;
 		break;
 #if defined(COMPAT_FREEBSD5) || defined(COMPAT_FREEBSD4) || defined(COMPAT_43)
 	case _IOC(IOC_IN, 'p', 3, 0):
@@ -124,43 +124,27 @@
 		*(unsigned int *)data = p->p_pfsflags;
 		break;
 	case PIOCWAIT:
-		while (p->p_step == 0 && (p->p_flag & P_WEXIT) == 0) {
-			/* sleep until p stops */
-			_PHOLD(p);
-			error = msleep(&p->p_stype, &p->p_mtx,
-			    PWAIT|PCATCH, "pioctl", 0);
-			_PRELE(p);
-			if (error != 0)
-				break;
-		}
-		/* fall through to PIOCSTATUS */
+		error = EOPNOTSUPP;
+		break;
 	case PIOCSTATUS:
 		ps = (struct procfs_status *)data;
-		ps->state = (p->p_step == 0);
+		ps->state = 1;
 		ps->flags = 0; /* nope */
-		ps->events = p->p_stops;
-		ps->why = p->p_step ? p->p_stype : 0;
-		ps->val = p->p_step ? p->p_xsig : 0;
+		ps->events = 0;
+		ps->why = 0;
+		ps->val = 0;
 		break;
 #ifdef COMPAT_FREEBSD32
 	case PIOCWAIT32:
-		while (p->p_step == 0 && (p->p_flag & P_WEXIT) == 0) {
-			/* sleep until p stops */
-			_PHOLD(p);
-			error = msleep(&p->p_stype, &p->p_mtx,
-			    PWAIT|PCATCH, "pioctl", 0);
-			_PRELE(p);
-			if (error != 0)
-				break;
-		}
-		/* fall through to PIOCSTATUS32 */
+		error = EOPNOTSUPP;
+		break;
 	case PIOCSTATUS32:
 		ps32 = (struct procfs_status32 *)data;
-		ps32->state = (p->p_step == 0);
+		ps32->state = 1;
 		ps32->flags = 0; /* nope */
-		ps32->events = p->p_stops;
-		ps32->why = p->p_step ? p->p_stype : 0;
-		ps32->val = p->p_step ? p->p_xsig : 0;
+		ps32->events = 0;
+		ps32->why = 0;
+		ps32->val = 0;
 		break;
 #endif
 #if defined(COMPAT_FREEBSD5) || defined(COMPAT_FREEBSD4) || defined(COMPAT_43)
@@ -172,29 +156,7 @@
 		data = &ival;
 #endif
 	case PIOCCONT:
-		if (p->p_step == 0)
-			break;
-		sig = *(unsigned int *)data;
-		if (sig != 0 && !_SIG_VALID(sig)) {
-			error = EINVAL;
-			break;
-		}
-#if 0
-		p->p_step = 0;
-		if (P_SHOULDSTOP(p)) {
-			p->p_xsig = sig;
-			p->p_flag &= ~(P_STOPPED_TRACE|P_STOPPED_SIG);
-			PROC_SLOCK(p);
-			thread_unsuspend(p);
-			PROC_SUNLOCK(p);
-		} else if (sig)
-			kern_psignal(p, sig);
-#else
-		if (sig)
-			kern_psignal(p, sig);
-		p->p_step = 0;
-		wakeup(&p->p_step);
-#endif
+		error = EOPNOTSUPP;
 		break;
 	default:
 		error = (ENOTTY);
@@ -212,9 +174,6 @@
 	if (p != NULL && (p->p_pfsflags & PF_LINGER) == 0) {
 		PROC_LOCK_ASSERT(p, MA_OWNED);
 		p->p_pfsflags = 0;
-		p->p_stops = 0;
-		p->p_step = 0;
-		wakeup(&p->p_step);
 	}
 	return (0);
 }
Index: sys/kern/kern_exec.c
===================================================================
--- sys/kern/kern_exec.c
+++ sys/kern/kern_exec.c
@@ -908,12 +908,6 @@
 				td->td_dbgflags |= TDB_EXEC;
 			PROC_UNLOCK(p);
 		}
-
-		/*
-		 * Stop the process here if its stop event mask has
-		 * the S_EXEC bit set.
-		 */
-		STOPEVENT(p, S_EXEC, 0);
 	} else {
 exec_fail:
 		/* we're done here, clear P_INEXEC */
Index: sys/kern/kern_exit.c
===================================================================
--- sys/kern/kern_exit.c
+++ sys/kern/kern_exit.c
@@ -280,15 +280,6 @@
 	p->p_xexit = rval;
 	p->p_xsig = signo;
 
-	/*
-	 * Wakeup anyone in procfs' PIOCWAIT.  They should have a hold
-	 * on our vmspace, so we should block below until they have
-	 * released their reference to us.  Note that if they have
-	 * requested S_EXIT stops we will block here until they ack
-	 * via PIOCCONT.
-	 */
-	_STOPEVENT(p, S_EXIT, 0);
-
 	/*
 	 * Ignore any pending request to stop due to a stop signal.
 	 * Once P_WEXIT is set, future requests will be ignored as
@@ -303,7 +294,6 @@
 	 * decided to wait again after we told them we are exiting.
 	 */
 	p->p_flag |= P_WEXIT;
-	wakeup(&p->p_stype);
 
 	/*
 	 * Wait for any processes that have a hold on our vmspace to
Index: sys/kern/kern_fork.c
===================================================================
--- sys/kern/kern_fork.c
+++ sys/kern/kern_fork.c
@@ -585,7 +585,6 @@
 	 * procfs ioctl flags from its parent.
 	 */
 	if (p1->p_pfsflags & PF_FORK) {
-		p2->p_stops = p1->p_stops;
 		p2->p_pfsflags = p1->p_pfsflags;
 	}
 
@@ -1109,7 +1108,6 @@
 		 */
 		PROC_LOCK(p);
 		td->td_dbgflags |= TDB_SCX;
-		_STOPEVENT(p, S_SCX, td->td_sa.code);
 		if ((p->p_ptevents & PTRACE_SCX) != 0 ||
 		    (td->td_dbgflags & TDB_BORN) != 0)
 			ptracestop(td, SIGTRAP, NULL);
Index: sys/kern/kern_prot.c
===================================================================
--- sys/kern/kern_prot.c
+++ sys/kern/kern_prot.c
@@ -2191,8 +2191,6 @@
 
 	PROC_LOCK_ASSERT(p, MA_OWNED);
 	p->p_flag |= P_SUGID;
-	if (!(p->p_pfsflags & PF_ISUGID))
-		p->p_stops = 0;
 }
 
 /*-
Index: sys/kern/kern_sig.c
===================================================================
--- sys/kern/kern_sig.c
+++ sys/kern/kern_sig.c
@@ -2248,14 +2248,6 @@
 	    !((prop & SIGPROP_CONT) && (p->p_flag & P_STOPPED_SIG)))
 		return (ret);
 
-	/* SIGKILL: Remove procfs STOPEVENTs. */
-	if (sig == SIGKILL) {
-		/* from procfs_ioctl.c: PIOCBIC */
-		p->p_stops = 0;
-		/* from procfs_ioctl.c: PIOCCONT */
-		p->p_step = 0;
-		wakeup(&p->p_step);
-	}
 	wakeup_swapper = 0;
 
 	/*
@@ -2852,7 +2844,7 @@
 	mtx_assert(&ps->ps_mtx, MA_OWNED);
 	PROC_LOCK_ASSERT(p, MA_OWNED);
 	for (;;) {
-		traced = (p->p_flag & P_TRACED) || (p->p_stops & S_SIG);
+		traced = (p->p_flag & P_TRACED);
 
 		sigpending = td->td_sigqueue.sq_signals;
 		SIGSETOR(sigpending, p->p_sigqueue.sq_signals);
@@ -2896,12 +2888,6 @@
 			sig = sig_ffs(&sigpending);
 		}
 
-		if (p->p_stops & S_SIG) {
-			mtx_unlock(&ps->ps_mtx);
-			stopevent(p, S_SIG, sig);
-			mtx_lock(&ps->ps_mtx);
-		}
-
 		/*
 		 * We should see pending but ignored signals
 		 * only if P_TRACED was on when they were posted.
@@ -3106,11 +3092,6 @@
 		ktrpsig(sig, action, td->td_pflags & TDP_OLDMASK ?
 		    &td->td_oldsigmask : &td->td_sigmask, ksi.ksi_code);
 #endif
-	if ((p->p_stops & S_SIG) != 0) {
-		mtx_unlock(&ps->ps_mtx);
-		stopevent(p, S_SIG, sig);
-		mtx_lock(&ps->ps_mtx);
-	}
 
 	if (action == SIG_DFL) {
 		/*
@@ -3655,7 +3636,6 @@
 
 	PROC_LOCK_ASSERT(p, MA_OWNED);
 	MPASS((p->p_flag & P_HADTHREADS) == 0 || p->p_singlethread == td);
-	_STOPEVENT(p, S_CORE, 0);
 
 	if (!do_coredump || (!sugid_coredump && (p->p_flag & P_SUGID) != 0) ||
 	    (p->p_flag2 & P2_NOTRACE) != 0) {
Index: sys/kern/subr_syscall.c
===================================================================
--- sys/kern/subr_syscall.c
+++ sys/kern/subr_syscall.c
@@ -90,7 +90,6 @@
 		goto retval;
 	}
 
-	STOPEVENT(p, S_SCE, sa->narg);
 	if (__predict_false((p->p_flag & P_TRACED) != 0)) {
 		PROC_LOCK(p);
 		if (p->p_ptevents & PTRACE_SCE)
@@ -227,7 +226,6 @@
 	 * register set.  If we ever support an emulation where this
 	 * is not the case, this code will need to be revisited.
 	 */
-	STOPEVENT(p, S_SCX, sa->code);
 	if (__predict_false(traced ||
 	    (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0)) {
 		PROC_LOCK(p);
Index: sys/kern/sys_process.c
===================================================================
--- sys/kern/sys_process.c
+++ sys/kern/sys_process.c
@@ -1524,26 +1524,3 @@
 }
 #undef PROC_READ
 #undef PROC_WRITE
-
-/*
- * Stop a process because of a debugging event;
- * stay stopped until p->p_step is cleared
- * (cleared by PIOCCONT in procfs).
- */
-void
-stopevent(struct proc *p, unsigned int event, unsigned int val)
-{
-
-	PROC_LOCK_ASSERT(p, MA_OWNED);
-	p->p_step = 1;
-	CTR3(KTR_PTRACE, "stopevent: pid %d event %u val %u", p->p_pid, event,
-	    val);
-	do {
-		if (event != S_EXIT)
-			p->p_xsig = val;
-		p->p_xthread = NULL;
-		p->p_stype = event;	/* Which event caused the stop? */
-		wakeup(&p->p_stype);	/* Wake up any PIOCWAIT'ing procs */
-		msleep(&p->p_step, &p->p_mtx, PWAIT, "stopevent", 0);
-	} while (p->p_step);
-}
Index: sys/sys/proc.h
===================================================================
--- sys/sys/proc.h
+++ sys/sys/proc.h
@@ -641,9 +641,9 @@
 	struct sigiolst	p_sigiolst;	/* (c) List of sigio sources. */
 	int		p_sigparent;	/* (c) Signal to parent on exit. */
 	int		p_sig;		/* (n) For core dump/debugger XXX. */
-	u_int		p_stops;	/* (c) Stop event bitmask. */
-	u_int		p_stype;	/* (c) Stop event type. */
-	char		p_step;		/* (c) Process is stopped. */
+	u_int		p_unused0;
+	u_int		p_unused1;
+	char		p_unused2;
 	u_char		p_pfsflags;	/* (c) Procfs flags. */
 	u_int		p_ptevents;	/* (c + e) ptrace() event mask. */
 	struct nlminfo	*p_nlminfo;	/* (?) Only used by/for lockd. */
@@ -860,24 +860,6 @@
 
 #define	SESS_LEADER(p)	((p)->p_session->s_leader == (p))
 
-
-#define	STOPEVENT(p, e, v) do {						\
-	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL,			\
- 	    "checking stopevent %d", (e));				\
-	if ((p)->p_stops & (e))	{					\
-		PROC_LOCK(p);						\
-		stopevent((p), (e), (v));				\
-		PROC_UNLOCK(p);						\
-	}								\
-} while (0)
-#define	_STOPEVENT(p, e, v) do {					\
-	PROC_LOCK_ASSERT(p, MA_OWNED);					\
-	WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, &p->p_mtx.lock_object, \
- 	    "checking stopevent %d", (e));				\
-	if ((p)->p_stops & (e))						\
-		stopevent((p), (e), (v));				\
-} while (0)
-
 /* Lock and unlock a process. */
 #define	PROC_LOCK(p)	mtx_lock(&(p)->p_mtx)
 #define	PROC_TRYLOCK(p)	mtx_trylock(&(p)->p_mtx)
@@ -1114,7 +1096,6 @@
 void	setsugid(struct proc *p);
 int	should_yield(void);
 int	sigonstack(size_t sp);
-void	stopevent(struct proc *, u_int, u_int);
 struct	thread *tdfind(lwpid_t, pid_t);
 void	threadinit(void);
 void	tidhash_add(struct thread *);