Modify the critical section API as follows:

- The MD functions critical_enter/exit are renamed to start with a cpu_
  prefix.
- MI wrapper functions critical_enter/exit maintain a per-thread nesting
  count and a per-thread critical section saved state set when entering
  a critical section while at nesting level 0 and restored when exiting
  to nesting level 0.  This moves the saved state out of spin mutexes so
  that interlocking spin mutexes works properly.
- Most low-level MD code that used critical_enter/exit now use
  cpu_critical_enter/exit.  MI code such as device drivers and spin
  mutexes use the MI wrappers.  Note that since the MI wrappers store
  the state in the current thread, they do not have any return values or
  arguments.
- mtx_intr_enable() is replaced with a constant CRITICAL_FORK which is
  assigned to curthread->td_savecrit during fork_exit().

Tested on:	i386, alpha

2 files changed, 112 insertions, 142 deletions

diff --git a/sys/dev/cy/cy.c b/sys/dev/cy/cy.c
index 20316ad..0510e72 100644
--- a/sys/dev/cy/cy.c
+++ b/sys/dev/cy/cy.c
@@ -356,7 +356,7 @@ static	int	cd_getreg	__P((struct com_s *com, int reg));
 static	void	cd_setreg	__P((struct com_s *com, int reg, int val));
 static	timeout_t siodtrwakeup;
 static	void	comhardclose	__P((struct com_s *com));
-static	void	sioinput	__P((struct com_s *com, critical_t *savecrit));
+static	void	sioinput	__P((struct com_s *com));
 #if 0
 static	void	siointr1	__P((struct com_s *com));
 #endif
@@ -673,7 +673,6 @@ sioopen(dev, flag, mode, td)
 	int		s;
 	struct tty	*tp;
 	int		unit;
-	critical_t	savecrit;
 
 	mynor = minor(dev);
 	unit = MINOR_TO_UNIT(mynor);
@@ -775,7 +774,7 @@ open_top:
 			}
 		}
 
-		savecrit = critical_enter();
+		critical_enter();
 		COM_LOCK();
 		(void) inb(com->line_status_port);
 		(void) inb(com->data_port);
@@ -784,7 +783,7 @@ open_top:
 		outb(iobase + com_ier, IER_ERXRDY | IER_ETXRDY | IER_ERLS
 				       | IER_EMSC);
 		COM_UNLOCK();
-		critical_exit(savecrit);
+		critical_exit();
 #else /* !0 */
 		/*
 		 * Flush fifos.  This requires a full channel reset which
@@ -795,7 +794,7 @@ open_top:
 				   CD1400_CCR_CMDRESET | CD1400_CCR_CHANRESET);
 		cd1400_channel_cmd(com, com->channel_control);
 
-		savecrit = critical_enter();
+		critical_enter();
 		COM_LOCK();
 		com->prev_modem_status = com->last_modem_status
 		    = cd_getreg(com, CD1400_MSVR2);
@@ -803,7 +802,7 @@ open_top:
 			  com->intr_enable
 			  = CD1400_SRER_MDMCH | CD1400_SRER_RXDATA);
 		COM_UNLOCK();
-		critical_exit(savecrit);
+		critical_exit();
 #endif /* 0 */
 		/*
 		 * Handle initial DCD.  Callout devices get a fake initial
@@ -886,7 +885,6 @@ comhardclose(com)
 	int		s;
 	struct tty	*tp;
 	int		unit;
-	critical_t	savecrit;
 
 	unit = com->unit;
 	iobase = com->iobase;
@@ -900,12 +898,12 @@ comhardclose(com)
 	outb(iobase + com_cfcr, com->cfcr_image &= ~CFCR_SBREAK);
 #else
 	/* XXX */
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 	com->etc = ETC_NONE;
 	cd_setreg(com, CD1400_COR2, com->cor[1] &= ~CD1400_COR2_ETC);
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 	cd1400_channel_cmd(com, CD1400_CCR_CMDRESET | CD1400_CCR_FTF);
 #endif
 
@@ -913,11 +911,11 @@ comhardclose(com)
 #if 0
 		outb(iobase + com_ier, 0);
 #else
-		savecrit = critical_enter();
+		critical_enter();
 		COM_LOCK();
 		cd_setreg(com, CD1400_SRER, com->intr_enable = 0);
 		COM_UNLOCK();
-		critical_exit(savecrit);
+		critical_exit();
 #endif
 		tp = com->tp;
 		if ((tp->t_cflag & HUPCL)
@@ -1013,9 +1011,8 @@ siodtrwakeup(chan)
  *  b) needs to return with COM_LOCK() held.
  */
 static void
-sioinput(com, savecrit)
+sioinput(com)
 	struct com_s	*com;
-	critical_t	*savecrit;
 {
 	u_char		*buf;
 	int		incc;
@@ -1046,7 +1043,7 @@ sioinput(com, savecrit)
 			 * that are used everywhere else.
 			 */
 			COM_UNLOCK();
-			critical_exit(*savecrit);
+			critical_exit();
 			incc = com->iptr - buf;
 			if (tp->t_rawq.c_cc + incc > tp->t_ihiwat
 			    && (com->state & CS_RTS_IFLOW
@@ -1067,7 +1064,7 @@ sioinput(com, savecrit)
 				tp->t_lflag &= ~FLUSHO;
 				comstart(tp);
 			}
-			*savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 		} while (buf < com->iptr);
 	} else {
@@ -1078,7 +1075,7 @@ sioinput(com, savecrit)
 			 * that are used everywhere else.
 			 */
 			COM_UNLOCK();
-			critical_exit(*savecrit);
+			critical_exit();
 			line_status = buf[com->ierroff];
 			recv_data = *buf++;
 			if (line_status
@@ -1093,7 +1090,7 @@ sioinput(com, savecrit)
 					recv_data |= TTY_PE;
 			}
 			(*linesw[tp->t_line].l_rint)(recv_data, tp);
-			*savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 		} while (buf < com->iptr);
 	}
@@ -1767,7 +1764,6 @@ static void
 siopoll(void *arg)
 {
 	int		unit;
-	critical_t	savecrit;
 
 #ifdef CyDebug
 	++cy_timeouts;
@@ -1790,7 +1786,7 @@ repeat:
 			 * (actually never opened devices) so that we don't
 			 * loop.
 			 */
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 			incc = com->iptr - com->ibuf;
 			com->iptr = com->ibuf;
@@ -1800,7 +1796,7 @@ repeat:
 			}
 			com_events -= incc;
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 			if (incc != 0)
 				log(LOG_DEBUG,
 				    "sio%d: %d events for device with no tp\n",
@@ -1808,36 +1804,36 @@ repeat:
 			continue;
 		}
 		if (com->iptr != com->ibuf) {
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
-			sioinput(com, &savecrit);
+			sioinput(com);
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 		}
 		if (com->state & CS_CHECKMSR) {
 			u_char	delta_modem_status;
 
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
-			sioinput(com, &savecrit);
+			sioinput(com);
 			delta_modem_status = com->last_modem_status
 					     ^ com->prev_modem_status;
 			com->prev_modem_status = com->last_modem_status;
 			com_events -= LOTS_OF_EVENTS;
 			com->state &= ~CS_CHECKMSR;
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 			if (delta_modem_status & MSR_DCD)
 				(*linesw[tp->t_line].l_modem)
 					(tp, com->prev_modem_status & MSR_DCD);
 		}
 		if (com->extra_state & CSE_ODONE) {
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 			com_events -= LOTS_OF_EVENTS;
 			com->extra_state &= ~CSE_ODONE;
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 			if (!(com->state & CS_BUSY)) {
 				tp->t_state &= ~TS_BUSY;
 				ttwwakeup(com->tp);
@@ -1849,12 +1845,12 @@ repeat:
 			}
 		}
 		if (com->state & CS_ODONE) {
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 			com_events -= LOTS_OF_EVENTS;
 			com->state &= ~CS_ODONE;
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 			(*linesw[tp->t_line].l_start)(tp);
 		}
 		if (com_events == 0)
@@ -1883,7 +1879,6 @@ comparam(tp, t)
 	u_char		opt;
 	int		s;
 	int		unit;
-	critical_t	savecrit;
 
 	/* do historical conversions */
 	if (t->c_ispeed == 0)
@@ -2031,14 +2026,14 @@ comparam(tp, t)
 	if (cflag & CCTS_OFLOW)
 		opt |= CD1400_COR2_CCTS_OFLOW;
 #endif
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 	if (opt != com->cor[1]) {
 		cor_change |= CD1400_CCR_COR2;
 		cd_setreg(com, CD1400_COR2, com->cor[1] = opt);
 	}
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 
 	/*
 	 * set channel option register 3 -
@@ -2159,7 +2154,7 @@ comparam(tp, t)
 	 * XXX should have done this long ago, but there is too much state
 	 * to change all atomically.
 	 */
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 
 	com->state &= ~CS_TTGO;
@@ -2227,7 +2222,7 @@ comparam(tp, t)
 	}
 
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 	splx(s);
 	comstart(tp);
 	if (com->ibufold != NULL) {
@@ -2246,7 +2241,6 @@ siosetwater(com, speed)
 	u_char		*ibuf;
 	int		ibufsize;
 	struct tty	*tp;
-	critical_t	savecrit;
 
 	/*
 	 * Make the buffer size large enough to handle a softtty interrupt
@@ -2284,10 +2278,10 @@ siosetwater(com, speed)
 	 * Read current input buffer, if any.  Continue with interrupts
 	 * disabled.
 	 */
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 	if (com->iptr != com->ibuf)
-		sioinput(com, &savecrit);
+		sioinput(com);
 
 	/*-
 	 * Initialize critical variables, including input buffer watermarks.
@@ -2306,7 +2300,7 @@ siosetwater(com, speed)
 	com->ihighwater = ibuf + 3 * ibufsize / 4;
 
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 	return (0);
 }
 
@@ -2320,7 +2314,6 @@ comstart(tp)
 	bool_t		started;
 #endif
 	int		unit;
-	critical_t	savecrit;
 
 	unit = DEV_TO_UNIT(tp->t_dev);
 	com = com_addr(unit);
@@ -2331,7 +2324,7 @@ comstart(tp)
 	started = FALSE;
 #endif
 
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 	if (tp->t_state & TS_TTSTOP) {
 		com->state &= ~CS_TTGO;
@@ -2369,7 +2362,7 @@ comstart(tp)
 #endif
 	}
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 	if (tp->t_state & (TS_TIMEOUT | TS_TTSTOP)) {
 		ttwwakeup(tp);
 		splx(s);
@@ -2388,7 +2381,7 @@ comstart(tp)
 						  sizeof com->obuf1);
 			com->obufs[0].l_next = NULL;
 			com->obufs[0].l_queued = TRUE;
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 			if (com->state & CS_BUSY) {
 				qp = com->obufq.l_next;
@@ -2409,7 +2402,7 @@ comstart(tp)
 						    | CD1400_SRER_TXRDY);
 			}
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 		}
 		if (tp->t_outq.c_cc != 0 && !com->obufs[1].l_queued) {
 #ifdef CyDebug
@@ -2420,7 +2413,7 @@ comstart(tp)
 						  sizeof com->obuf2);
 			com->obufs[1].l_next = NULL;
 			com->obufs[1].l_queued = TRUE;
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 			if (com->state & CS_BUSY) {
 				qp = com->obufq.l_next;
@@ -2441,7 +2434,7 @@ comstart(tp)
 						    | CD1400_SRER_TXRDY);
 			}
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 		}
 		tp->t_state |= TS_BUSY;
 	}
@@ -2450,12 +2443,12 @@ comstart(tp)
 		++com->start_real;
 #endif
 #if 0
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 	if (com->state >= (CS_BUSY | CS_TTGO))
 		siointr1(com);	/* fake interrupt to start output */
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 #endif
 	ttwwakeup(tp);
 	splx(s);
@@ -2468,11 +2461,10 @@ comstop(tp, rw)
 {
 	struct com_s	*com;
 	bool_t		wakeup_etc;
-	critical_t	savecrit;
 
 	com = com_addr(DEV_TO_UNIT(tp->t_dev));
 	wakeup_etc = FALSE;
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 	if (rw & FWRITE) {
 		com->obufs[0].l_queued = FALSE;
@@ -2497,7 +2489,7 @@ comstop(tp, rw)
 		com->iptr = com->ibuf;
 	}
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 	if (wakeup_etc)
 		wakeup(&com->etc);
 	if (rw & FWRITE && com->etc == ETC_NONE)
@@ -2513,7 +2505,6 @@ commctl(com, bits, how)
 {
 	int	mcr;
 	int	msr;
-	critical_t	savecrit;
 
 	if (how == DMGET) {
 		if (com->channel_control & CD1400_CCR_RCVEN)
@@ -2551,7 +2542,7 @@ commctl(com, bits, how)
 		mcr |= com->mcr_dtr;
 	if (bits & TIOCM_RTS)
 		mcr |= com->mcr_rts;
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 	switch (how) {
 	case DMSET:
@@ -2571,7 +2562,7 @@ commctl(com, bits, how)
 		break;
 	}
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 	return (0);
 }
 
@@ -2633,13 +2624,11 @@ comwakeup(chan)
 		com = com_addr(unit);
 		if (com != NULL
 		    && (com->state >= (CS_BUSY | CS_TTGO) || com->poll)) {
-			critical_t	savecrit;
-
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 			siointr1(com);
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 		}
 	}
 #endif
@@ -2659,14 +2648,13 @@ comwakeup(chan)
 		for (errnum = 0; errnum < CE_NTYPES; ++errnum) {
 			u_int	delta;
 			u_long	total;
-			critical_t	savecrit;
 
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 			delta = com->delta_error_counts[errnum];
 			com->delta_error_counts[errnum] = 0;
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 			if (delta == 0)
 				continue;
 			total = com->error_counts[errnum] += delta;
@@ -2818,7 +2806,6 @@ cd_etc(com, etc)
 	struct com_s	*com;
 	int		etc;
 {
-	critical_t	savecrit;
 
 	/*
 	 * We can't change the hardware's ETC state while there are any
@@ -2831,7 +2818,7 @@ cd_etc(com, etc)
 	 * for the tx to become empty so that the command is sure to be
 	 * executed soon after we issue it.
 	 */
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 	if (com->etc == etc)
 		goto wait;
@@ -2842,7 +2829,7 @@ cd_etc(com, etc)
 	       && (com->etc == ETC_BREAK_ENDING || com->etc == ETC_BREAK_ENDED
 		   || com->etc == ETC_NONE))) {
 		COM_UNLOCK();
-		critical_exit(savecrit);
+		critical_exit();
 		return;
 	}
 	com->etc = etc;
@@ -2851,7 +2838,7 @@ cd_etc(com, etc)
 		  = (com->intr_enable & ~CD1400_SRER_TXRDY) | CD1400_SRER_TXMPTY);
 wait:
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 	while (com->etc == etc
 	       && tsleep(&com->etc, TTIPRI | PCATCH, "cyetc", 0) == 0)
 		continue;
@@ -2865,7 +2852,6 @@ cd_getreg(com, reg)
 	struct com_s	*basecom;
 	u_char	car;
 	int	cy_align;
-	critical_t	savecrit;
 	register_t	eflags;
 	cy_addr	iobase;
 	int	val;
@@ -2875,7 +2861,7 @@ cd_getreg(com, reg)
 	cy_align = com->cy_align;
 	iobase = com->iobase;
 	eflags = read_eflags();
-	savecrit = critical_enter();
+	critical_enter();
 	if (eflags & PSL_I)
 		COM_LOCK();
 	if (basecom->car != car)
@@ -2883,7 +2869,7 @@ cd_getreg(com, reg)
 	val = cd_inb(iobase, reg, cy_align);
 	if (eflags & PSL_I)
 		COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 	return (val);
 }
 
@@ -2896,7 +2882,6 @@ cd_setreg(com, reg, val)
 	struct com_s	*basecom;
 	u_char	car;
 	int	cy_align;
-	critical_t	savecrit;
 	register_t	eflags;
 	cy_addr	iobase;
 
@@ -2905,7 +2890,7 @@ cd_setreg(com, reg, val)
 	cy_align = com->cy_align;
 	iobase = com->iobase;
 	eflags = read_eflags();
-	savecrit = critical_enter();
+	critical_enter();
 	if (eflags & PSL_I)
 		COM_LOCK();
 	if (basecom->car != car)
@@ -2913,7 +2898,7 @@ cd_setreg(com, reg, val)
 	cd_outb(iobase, reg, cy_align, val);
 	if (eflags & PSL_I)
 		COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 }
 
 #ifdef CyDebug
diff --git a/sys/dev/cy/cy_isa.c b/sys/dev/cy/cy_isa.c
index 20316ad..0510e72 100644
--- a/sys/dev/cy/cy_isa.c
+++ b/sys/dev/cy/cy_isa.c
@@ -356,7 +356,7 @@ static	int	cd_getreg	__P((struct com_s *com, int reg));
 static	void	cd_setreg	__P((struct com_s *com, int reg, int val));
 static	timeout_t siodtrwakeup;
 static	void	comhardclose	__P((struct com_s *com));
-static	void	sioinput	__P((struct com_s *com, critical_t *savecrit));
+static	void	sioinput	__P((struct com_s *com));
 #if 0
 static	void	siointr1	__P((struct com_s *com));
 #endif
@@ -673,7 +673,6 @@ sioopen(dev, flag, mode, td)
 	int		s;
 	struct tty	*tp;
 	int		unit;
-	critical_t	savecrit;
 
 	mynor = minor(dev);
 	unit = MINOR_TO_UNIT(mynor);
@@ -775,7 +774,7 @@ open_top:
 			}
 		}
 
-		savecrit = critical_enter();
+		critical_enter();
 		COM_LOCK();
 		(void) inb(com->line_status_port);
 		(void) inb(com->data_port);
@@ -784,7 +783,7 @@ open_top:
 		outb(iobase + com_ier, IER_ERXRDY | IER_ETXRDY | IER_ERLS
 				       | IER_EMSC);
 		COM_UNLOCK();
-		critical_exit(savecrit);
+		critical_exit();
 #else /* !0 */
 		/*
 		 * Flush fifos.  This requires a full channel reset which
@@ -795,7 +794,7 @@ open_top:
 				   CD1400_CCR_CMDRESET | CD1400_CCR_CHANRESET);
 		cd1400_channel_cmd(com, com->channel_control);
 
-		savecrit = critical_enter();
+		critical_enter();
 		COM_LOCK();
 		com->prev_modem_status = com->last_modem_status
 		    = cd_getreg(com, CD1400_MSVR2);
@@ -803,7 +802,7 @@ open_top:
 			  com->intr_enable
 			  = CD1400_SRER_MDMCH | CD1400_SRER_RXDATA);
 		COM_UNLOCK();
-		critical_exit(savecrit);
+		critical_exit();
 #endif /* 0 */
 		/*
 		 * Handle initial DCD.  Callout devices get a fake initial
@@ -886,7 +885,6 @@ comhardclose(com)
 	int		s;
 	struct tty	*tp;
 	int		unit;
-	critical_t	savecrit;
 
 	unit = com->unit;
 	iobase = com->iobase;
@@ -900,12 +898,12 @@ comhardclose(com)
 	outb(iobase + com_cfcr, com->cfcr_image &= ~CFCR_SBREAK);
 #else
 	/* XXX */
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 	com->etc = ETC_NONE;
 	cd_setreg(com, CD1400_COR2, com->cor[1] &= ~CD1400_COR2_ETC);
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 	cd1400_channel_cmd(com, CD1400_CCR_CMDRESET | CD1400_CCR_FTF);
 #endif
 
@@ -913,11 +911,11 @@ comhardclose(com)
 #if 0
 		outb(iobase + com_ier, 0);
 #else
-		savecrit = critical_enter();
+		critical_enter();
 		COM_LOCK();
 		cd_setreg(com, CD1400_SRER, com->intr_enable = 0);
 		COM_UNLOCK();
-		critical_exit(savecrit);
+		critical_exit();
 #endif
 		tp = com->tp;
 		if ((tp->t_cflag & HUPCL)
@@ -1013,9 +1011,8 @@ siodtrwakeup(chan)
  *  b) needs to return with COM_LOCK() held.
  */
 static void
-sioinput(com, savecrit)
+sioinput(com)
 	struct com_s	*com;
-	critical_t	*savecrit;
 {
 	u_char		*buf;
 	int		incc;
@@ -1046,7 +1043,7 @@ sioinput(com, savecrit)
 			 * that are used everywhere else.
 			 */
 			COM_UNLOCK();
-			critical_exit(*savecrit);
+			critical_exit();
 			incc = com->iptr - buf;
 			if (tp->t_rawq.c_cc + incc > tp->t_ihiwat
 			    && (com->state & CS_RTS_IFLOW
@@ -1067,7 +1064,7 @@ sioinput(com, savecrit)
 				tp->t_lflag &= ~FLUSHO;
 				comstart(tp);
 			}
-			*savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 		} while (buf < com->iptr);
 	} else {
@@ -1078,7 +1075,7 @@ sioinput(com, savecrit)
 			 * that are used everywhere else.
 			 */
 			COM_UNLOCK();
-			critical_exit(*savecrit);
+			critical_exit();
 			line_status = buf[com->ierroff];
 			recv_data = *buf++;
 			if (line_status
@@ -1093,7 +1090,7 @@ sioinput(com, savecrit)
 					recv_data |= TTY_PE;
 			}
 			(*linesw[tp->t_line].l_rint)(recv_data, tp);
-			*savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 		} while (buf < com->iptr);
 	}
@@ -1767,7 +1764,6 @@ static void
 siopoll(void *arg)
 {
 	int		unit;
-	critical_t	savecrit;
 
 #ifdef CyDebug
 	++cy_timeouts;
@@ -1790,7 +1786,7 @@ repeat:
 			 * (actually never opened devices) so that we don't
 			 * loop.
 			 */
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 			incc = com->iptr - com->ibuf;
 			com->iptr = com->ibuf;
@@ -1800,7 +1796,7 @@ repeat:
 			}
 			com_events -= incc;
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 			if (incc != 0)
 				log(LOG_DEBUG,
 				    "sio%d: %d events for device with no tp\n",
@@ -1808,36 +1804,36 @@ repeat:
 			continue;
 		}
 		if (com->iptr != com->ibuf) {
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
-			sioinput(com, &savecrit);
+			sioinput(com);
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 		}
 		if (com->state & CS_CHECKMSR) {
 			u_char	delta_modem_status;
 
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
-			sioinput(com, &savecrit);
+			sioinput(com);
 			delta_modem_status = com->last_modem_status
 					     ^ com->prev_modem_status;
 			com->prev_modem_status = com->last_modem_status;
 			com_events -= LOTS_OF_EVENTS;
 			com->state &= ~CS_CHECKMSR;
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 			if (delta_modem_status & MSR_DCD)
 				(*linesw[tp->t_line].l_modem)
 					(tp, com->prev_modem_status & MSR_DCD);
 		}
 		if (com->extra_state & CSE_ODONE) {
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 			com_events -= LOTS_OF_EVENTS;
 			com->extra_state &= ~CSE_ODONE;
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 			if (!(com->state & CS_BUSY)) {
 				tp->t_state &= ~TS_BUSY;
 				ttwwakeup(com->tp);
@@ -1849,12 +1845,12 @@ repeat:
 			}
 		}
 		if (com->state & CS_ODONE) {
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 			com_events -= LOTS_OF_EVENTS;
 			com->state &= ~CS_ODONE;
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 			(*linesw[tp->t_line].l_start)(tp);
 		}
 		if (com_events == 0)
@@ -1883,7 +1879,6 @@ comparam(tp, t)
 	u_char		opt;
 	int		s;
 	int		unit;
-	critical_t	savecrit;
 
 	/* do historical conversions */
 	if (t->c_ispeed == 0)
@@ -2031,14 +2026,14 @@ comparam(tp, t)
 	if (cflag & CCTS_OFLOW)
 		opt |= CD1400_COR2_CCTS_OFLOW;
 #endif
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 	if (opt != com->cor[1]) {
 		cor_change |= CD1400_CCR_COR2;
 		cd_setreg(com, CD1400_COR2, com->cor[1] = opt);
 	}
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 
 	/*
 	 * set channel option register 3 -
@@ -2159,7 +2154,7 @@ comparam(tp, t)
 	 * XXX should have done this long ago, but there is too much state
 	 * to change all atomically.
 	 */
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 
 	com->state &= ~CS_TTGO;
@@ -2227,7 +2222,7 @@ comparam(tp, t)
 	}
 
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 	splx(s);
 	comstart(tp);
 	if (com->ibufold != NULL) {
@@ -2246,7 +2241,6 @@ siosetwater(com, speed)
 	u_char		*ibuf;
 	int		ibufsize;
 	struct tty	*tp;
-	critical_t	savecrit;
 
 	/*
 	 * Make the buffer size large enough to handle a softtty interrupt
@@ -2284,10 +2278,10 @@ siosetwater(com, speed)
 	 * Read current input buffer, if any.  Continue with interrupts
 	 * disabled.
 	 */
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 	if (com->iptr != com->ibuf)
-		sioinput(com, &savecrit);
+		sioinput(com);
 
 	/*-
 	 * Initialize critical variables, including input buffer watermarks.
@@ -2306,7 +2300,7 @@ siosetwater(com, speed)
 	com->ihighwater = ibuf + 3 * ibufsize / 4;
 
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 	return (0);
 }
 
@@ -2320,7 +2314,6 @@ comstart(tp)
 	bool_t		started;
 #endif
 	int		unit;
-	critical_t	savecrit;
 
 	unit = DEV_TO_UNIT(tp->t_dev);
 	com = com_addr(unit);
@@ -2331,7 +2324,7 @@ comstart(tp)
 	started = FALSE;
 #endif
 
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 	if (tp->t_state & TS_TTSTOP) {
 		com->state &= ~CS_TTGO;
@@ -2369,7 +2362,7 @@ comstart(tp)
 #endif
 	}
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 	if (tp->t_state & (TS_TIMEOUT | TS_TTSTOP)) {
 		ttwwakeup(tp);
 		splx(s);
@@ -2388,7 +2381,7 @@ comstart(tp)
 						  sizeof com->obuf1);
 			com->obufs[0].l_next = NULL;
 			com->obufs[0].l_queued = TRUE;
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 			if (com->state & CS_BUSY) {
 				qp = com->obufq.l_next;
@@ -2409,7 +2402,7 @@ comstart(tp)
 						    | CD1400_SRER_TXRDY);
 			}
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 		}
 		if (tp->t_outq.c_cc != 0 && !com->obufs[1].l_queued) {
 #ifdef CyDebug
@@ -2420,7 +2413,7 @@ comstart(tp)
 						  sizeof com->obuf2);
 			com->obufs[1].l_next = NULL;
 			com->obufs[1].l_queued = TRUE;
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 			if (com->state & CS_BUSY) {
 				qp = com->obufq.l_next;
@@ -2441,7 +2434,7 @@ comstart(tp)
 						    | CD1400_SRER_TXRDY);
 			}
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 		}
 		tp->t_state |= TS_BUSY;
 	}
@@ -2450,12 +2443,12 @@ comstart(tp)
 		++com->start_real;
 #endif
 #if 0
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 	if (com->state >= (CS_BUSY | CS_TTGO))
 		siointr1(com);	/* fake interrupt to start output */
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 #endif
 	ttwwakeup(tp);
 	splx(s);
@@ -2468,11 +2461,10 @@ comstop(tp, rw)
 {
 	struct com_s	*com;
 	bool_t		wakeup_etc;
-	critical_t	savecrit;
 
 	com = com_addr(DEV_TO_UNIT(tp->t_dev));
 	wakeup_etc = FALSE;
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 	if (rw & FWRITE) {
 		com->obufs[0].l_queued = FALSE;
@@ -2497,7 +2489,7 @@ comstop(tp, rw)
 		com->iptr = com->ibuf;
 	}
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 	if (wakeup_etc)
 		wakeup(&com->etc);
 	if (rw & FWRITE && com->etc == ETC_NONE)
@@ -2513,7 +2505,6 @@ commctl(com, bits, how)
 {
 	int	mcr;
 	int	msr;
-	critical_t	savecrit;
 
 	if (how == DMGET) {
 		if (com->channel_control & CD1400_CCR_RCVEN)
@@ -2551,7 +2542,7 @@ commctl(com, bits, how)
 		mcr |= com->mcr_dtr;
 	if (bits & TIOCM_RTS)
 		mcr |= com->mcr_rts;
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 	switch (how) {
 	case DMSET:
@@ -2571,7 +2562,7 @@ commctl(com, bits, how)
 		break;
 	}
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 	return (0);
 }
 
@@ -2633,13 +2624,11 @@ comwakeup(chan)
 		com = com_addr(unit);
 		if (com != NULL
 		    && (com->state >= (CS_BUSY | CS_TTGO) || com->poll)) {
-			critical_t	savecrit;
-
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 			siointr1(com);
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 		}
 	}
 #endif
@@ -2659,14 +2648,13 @@ comwakeup(chan)
 		for (errnum = 0; errnum < CE_NTYPES; ++errnum) {
 			u_int	delta;
 			u_long	total;
-			critical_t	savecrit;
 
-			savecrit = critical_enter();
+			critical_enter();
 			COM_LOCK();
 			delta = com->delta_error_counts[errnum];
 			com->delta_error_counts[errnum] = 0;
 			COM_UNLOCK();
-			critical_exit(savecrit);
+			critical_exit();
 			if (delta == 0)
 				continue;
 			total = com->error_counts[errnum] += delta;
@@ -2818,7 +2806,6 @@ cd_etc(com, etc)
 	struct com_s	*com;
 	int		etc;
 {
-	critical_t	savecrit;
 
 	/*
 	 * We can't change the hardware's ETC state while there are any
@@ -2831,7 +2818,7 @@ cd_etc(com, etc)
 	 * for the tx to become empty so that the command is sure to be
 	 * executed soon after we issue it.
 	 */
-	savecrit = critical_enter();
+	critical_enter();
 	COM_LOCK();
 	if (com->etc == etc)
 		goto wait;
@@ -2842,7 +2829,7 @@ cd_etc(com, etc)
 	       && (com->etc == ETC_BREAK_ENDING || com->etc == ETC_BREAK_ENDED
 		   || com->etc == ETC_NONE))) {
 		COM_UNLOCK();
-		critical_exit(savecrit);
+		critical_exit();
 		return;
 	}
 	com->etc = etc;
@@ -2851,7 +2838,7 @@ cd_etc(com, etc)
 		  = (com->intr_enable & ~CD1400_SRER_TXRDY) | CD1400_SRER_TXMPTY);
 wait:
 	COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 	while (com->etc == etc
 	       && tsleep(&com->etc, TTIPRI | PCATCH, "cyetc", 0) == 0)
 		continue;
@@ -2865,7 +2852,6 @@ cd_getreg(com, reg)
 	struct com_s	*basecom;
 	u_char	car;
 	int	cy_align;
-	critical_t	savecrit;
 	register_t	eflags;
 	cy_addr	iobase;
 	int	val;
@@ -2875,7 +2861,7 @@ cd_getreg(com, reg)
 	cy_align = com->cy_align;
 	iobase = com->iobase;
 	eflags = read_eflags();
-	savecrit = critical_enter();
+	critical_enter();
 	if (eflags & PSL_I)
 		COM_LOCK();
 	if (basecom->car != car)
@@ -2883,7 +2869,7 @@ cd_getreg(com, reg)
 	val = cd_inb(iobase, reg, cy_align);
 	if (eflags & PSL_I)
 		COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 	return (val);
 }
 
@@ -2896,7 +2882,6 @@ cd_setreg(com, reg, val)
 	struct com_s	*basecom;
 	u_char	car;
 	int	cy_align;
-	critical_t	savecrit;
 	register_t	eflags;
 	cy_addr	iobase;
 
@@ -2905,7 +2890,7 @@ cd_setreg(com, reg, val)
 	cy_align = com->cy_align;
 	iobase = com->iobase;
 	eflags = read_eflags();
-	savecrit = critical_enter();
+	critical_enter();
 	if (eflags & PSL_I)
 		COM_LOCK();
 	if (basecom->car != car)
@@ -2913,7 +2898,7 @@ cd_setreg(com, reg, val)
 	cd_outb(iobase, reg, cy_align, val);
 	if (eflags & PSL_I)
 		COM_UNLOCK();
-	critical_exit(savecrit);
+	critical_exit();
 }
 
 #ifdef CyDebug