Index: fifo_vnops.c
===================================================================
RCS file: /home/ncvs/src/sys/fs/fifofs/fifo_vnops.c,v
retrieving revision 1.126
diff -u -r1.126 fifo_vnops.c
--- fifo_vnops.c	18 Sep 2005 10:44:50 -0000	1.126
+++ fifo_vnops.c	21 Sep 2005 16:44:55 -0000
@@ -82,6 +82,7 @@
 	struct socket	*fi_writesock;
 	long		fi_readers;
 	long		fi_writers;
+	struct sx	fi_sx;
 };
 
 static vop_print_t	fifo_print;
@@ -152,6 +153,7 @@
 		vp->v_fifoinfo = NULL;
 		(void)soclose(fip->fi_readsock);
 		(void)soclose(fip->fi_writesock);
+		sx_destroy(&fip->fi_sx);
 		FREE(fip, M_VNODE);
 	}
 }
@@ -179,7 +181,8 @@
 	int error;
 
 	if ((fip = vp->v_fifoinfo) == NULL) {
-		MALLOC(fip, struct fifoinfo *, sizeof(*fip), M_VNODE, M_WAITOK);
+		MALLOC(fip, struct fifoinfo *, sizeof(*fip), M_VNODE,
+		    M_WAITOK | M_ZERO);
 		error = socreate(AF_LOCAL, &rso, SOCK_STREAM, 0, cred, td);
 		if (error)
 			goto fail1;
@@ -198,6 +201,7 @@
 			return (error);
 		}
 		fip->fi_readers = fip->fi_writers = 0;
+		sx_init(&fip->fi_sx, "fifo_sx");
 		wso->so_snd.sb_lowat = PIPE_BUF;
 		SOCKBUF_LOCK(&rso->so_rcv);
 		rso->so_rcv.sb_state |= SBS_CANTRCVMORE;
@@ -703,7 +707,9 @@
 	if (uio->uio_resid == 0)
 		return (0);
 	sflags = (fp->f_flag & FNONBLOCK) ? MSG_NBIO : 0;
+	sx_xlock(&fip->fi_sx);
 	error = soreceive(fip->fi_readsock, NULL, uio, NULL, NULL, &sflags);
+	sx_xunlock(&fip->fi_sx);
 	return (error);
 }
 
@@ -723,6 +729,8 @@
 	fip = fp->f_data;
 	KASSERT(uio->uio_rw == UIO_WRITE,("fifo_write mode"));
 	sflags = (fp->f_flag & FNONBLOCK) ? MSG_NBIO : 0;
+	sx_xlock(&fip->fi_sx);
 	error = sosend(fip->fi_writesock, NULL, uio, 0, NULL, sflags, td);
+	sx_xunlock(&fip->fi_sx);
 	return (error);
 }