Index: subr_log.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/subr_log.c,v
retrieving revision 1.60
diff -u -r1.60 subr_log.c
--- subr_log.c	21 Feb 2004 21:10:52 -0000	1.60
+++ subr_log.c	22 Mar 2004 13:55:51 -0000
@@ -87,7 +87,12 @@
 	struct	callout sc_callout;	/* callout to wakeup syslog  */
 } logsoftc;
 
-int	log_open;			/* also used in log() */
+/*
+ * log_mtx protects logsoftc, log_open.  Note that log_mtx does not protect
+ * the structures associated with msgbuf, which require Giant.
+ */
+struct mtx	log_mtx;
+int		log_open;			/* also used in log() */
 
 /* Times per second to check for a pending syslog wakeup. */
 static int	log_wakeups_per_second = 5;
@@ -98,17 +103,24 @@
 static	int
 logopen(dev_t dev, int flags, int mode, struct thread *td)
 {
-	if (log_open)
+
+	mtx_lock(&log_mtx);
+	if (log_open) {
+		mtx_unlock(&log_mtx);
 		return (EBUSY);
+	}
 	log_open = 1;
-	callout_init(&logsoftc.sc_callout, 0);
+	callout_init(&logsoftc.sc_callout, CALLOUT_MPSAFE);
+	mtx_unlock(&log_mtx);
 	fsetown(td->td_proc->p_pid, &logsoftc.sc_sigio);	/* signal process only */
+	mtx_lock(&log_mtx);
 	if (log_wakeups_per_second < 1) {
 		printf("syslog wakeup is less than one.  Adjusting to 1.\n");
 		log_wakeups_per_second = 1;
 	}
 	callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
 	    logtimeout, NULL);
+	mtx_unlock(&log_mtx);
 	return (0);
 }
 
@@ -117,9 +129,11 @@
 logclose(dev_t dev, int flag, int mode, struct thread *td)
 {
 
+	mtx_lock(&log_mtx);
 	log_open = 0;
 	callout_stop(&logsoftc.sc_callout);
 	logsoftc.sc_state = 0;
+	mtx_unlock(&log_mtx);
 	funsetown(&logsoftc.sc_sigio);
 	return (0);
 }
@@ -138,14 +152,18 @@
 			splx(s);
 			return (EWOULDBLOCK);
 		}
+		mtx_lock(&log_mtx);
 		logsoftc.sc_state |= LOG_RDWAIT;
+		mtx_unlock(&log_mtx);
 		if ((error = tsleep(mbp, LOG_RDPRI | PCATCH, "klog", 0))) {
 			splx(s);
 			return (error);
 		}
 	}
 	splx(s);
+	mtx_lock(&log_mtx);
 	logsoftc.sc_state &= ~LOG_RDWAIT;
+	mtx_unlock(&log_mtx);
 
 	while (uio->uio_resid > 0) {
 		l = imin(sizeof(buf), uio->uio_resid);
@@ -182,8 +200,11 @@
 logtimeout(void *arg)
 {
 
-	if (!log_open)
+	mtx_lock(&log_mtx);
+	if (!log_open) {
+		mtx_unlock(&log_mtx);
 		return;
+	}
 	if (log_wakeups_per_second < 1) {
 		printf("syslog wakeup is less than one.  Adjusting to 1.\n");
 		log_wakeups_per_second = 1;
@@ -191,6 +212,7 @@
 	if (msgbuftrigger == 0) {
 		callout_reset(&logsoftc.sc_callout,
 		    hz / log_wakeups_per_second, logtimeout, NULL);
+		mtx_unlock(&log_mtx);
 		return;
 	}
 	msgbuftrigger = 0;
@@ -203,6 +225,7 @@
 	}
 	callout_reset(&logsoftc.sc_callout, hz / log_wakeups_per_second,
 	    logtimeout, NULL);
+	mtx_unlock(&log_mtx);
 }
 
 /*ARGSUSED*/
@@ -221,10 +244,12 @@
 		break;
 
 	case FIOASYNC:
+		mtx_lock(&log_mtx);
 		if (*(int *)data)
 			logsoftc.sc_state |= LOG_ASYNC;
 		else
 			logsoftc.sc_state &= ~LOG_ASYNC;
+		mtx_unlock(&log_mtx);
 		break;
 
 	case FIOSETOWN:
@@ -253,6 +278,7 @@
 log_drvinit(void *unused)
 {
 
+	mtx_init(&log_mtx, "log_mtx", NULL, MTX_DEF);
 	make_dev(&log_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, "klog");
 }