Behave correctly in interrupt handlers if no tty has been allocated yet.

Prevents monkeys pounding on your serial terminal from panicing your kernel
before getty gets spawned on the serial ports.

dcm(4) looks safe from this problem from code inspection.

1 files changed, 37 insertions, 22 deletions

diff --git a/sys/arch/hp300/dev/dca.c b/sys/arch/hp300/dev/dca.c
index dd56bbe17ae..71ccfc3e13f 100644
--- a/sys/arch/hp300/dev/dca.c
+++ b/sys/arch/hp300/dev/dca.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: dca.c,v 1.24 2005/02/12 18:01:08 miod Exp $	*/
+/*	$OpenBSD: dca.c,v 1.25 2005/02/14 00:52:09 miod Exp $	*/
 /*	$NetBSD: dca.c,v 1.35 1997/05/05 20:58:18 thorpej Exp $	*/
 
 /*
@@ -521,6 +521,7 @@ dcaintr(arg)
 #ifdef DEBUG
 		dcaintrcount[code & IIR_IMASK]++;
 #endif
+
 		switch (code & IIR_IMASK) {
 		case IIR_NOPEND:
 			return (1);
@@ -533,16 +534,18 @@ dcaintr(arg)
 #ifdef KGDB
 #define	RCVBYTE() \
 			code = dca->dca_data; \
-			if ((tp->t_state & TS_ISOPEN) == 0) { \
-				if (code == FRAME_END && \
-				    kgdb_dev == makedev(dcamajor, unit)) \
-					kgdb_connect(0); /* trap into kgdb */ \
-			} else \
-				(*linesw[tp->t_line].l_rint)(code, tp)
+			if (tp != NULL) { \
+				if ((tp->t_state & TS_ISOPEN) == 0) { \
+					if (code == FRAME_END && \
+					    kgdb_dev == makedev(dcamajor, unit)) \
+						kgdb_connect(0); /* trap into kgdb */ \
+				} else \
+					(*linesw[tp->t_line].l_rint)(code, tp) \
+			}
 #else
 #define	RCVBYTE() \
 			code = dca->dca_data; \
-			if ((tp->t_state & TS_ISOPEN) != 0) \
+			if (tp != NULL && (tp->t_state & TS_ISOPEN) != 0) \
 				(*linesw[tp->t_line].l_rint)(code, tp)
 #endif
 			RCVBYTE();
@@ -573,11 +576,13 @@ dcaintr(arg)
 			}
 			break;
 		case IIR_TXRDY:
-			tp->t_state &=~ (TS_BUSY|TS_FLUSH);
-			if (tp->t_line)
-				(*linesw[tp->t_line].l_start)(tp);
-			else
-				dcastart(tp);
+			if (tp != NULL) {
+				tp->t_state &=~ (TS_BUSY|TS_FLUSH);
+				if (tp->t_line)
+					(*linesw[tp->t_line].l_start)(tp);
+				else
+					dcastart(tp);
+			}
 			break;
 		case IIR_RLS:
 			dcaeint(sc, dca->dca_lsr);
@@ -587,7 +592,7 @@ dcaintr(arg)
 				return (1);
 			log(LOG_WARNING, "%s: weird interrupt: 0x%x\n",
 			    sc->sc_dev.dv_xname, code);
-			/* fall through */
+			/* FALLTHROUGH */
 		case IIR_MLSC:
 			dcamint(sc);
 			break;
@@ -605,22 +610,28 @@ dcaeint(sc, stat)
 	int c;
 
 	c = dca->dca_data;
+
+#if defined(DDB) && !defined(KGDB)
+	if ((sc->sc_flags & DCA_ISCONSOLE) && db_console && (stat & LSR_BI)) {
+		Debugger();
+		return;
+	}
+#endif
+
+	if (tp == NULL)
+		return;
+
 	if ((tp->t_state & TS_ISOPEN) == 0) {
 #ifdef KGDB
 		/* we don't care about parity errors */
 		if (((stat & (LSR_BI|LSR_FE|LSR_PE)) == LSR_PE) &&
-		    kgdb_dev == makedev(dcamajor, sc->sc_hd->hp_unit)
-		    && c == FRAME_END)
+		    kgdb_dev == makedev(dcamajor, sc->sc_hd->hp_unit) &&
+		    c == FRAME_END)
 			kgdb_connect(0); /* trap into kgdb */
 #endif
 		return;
 	}
-#if defined(DDB) && !defined(KGDB)
-	if ((sc->sc_flags & DCA_ISCONSOLE) && db_console && (stat & LSR_BI)) {
-		Debugger();
-		return;
-	}
-#endif
+
 	if (stat & (LSR_BI | LSR_FE))
 		c |= TTY_FE;
 	else if (stat & LSR_PE)
@@ -642,6 +653,10 @@ dcamint(sc)
 #ifdef DEBUG
 	dcamintcount[stat & 0xf]++;
 #endif
+
+	if (tp == NULL)
+		return;
+
 	if ((stat & MSR_DDCD) &&
 	    (sc->sc_flags & DCA_SOFTCAR) == 0) {
 		if (stat & MSR_DCD)