Device megapatch 2/6:

This commit adds a couple of functions for pseudodrivers to use for
implementing cloning in a manner we will be able to lock down (shortly).

Basically what happens is that pseudo drivers get a way to ask for
"give me the dev_t with this unit number" or alternatively "give
me a dev_t with the lowest guaranteed free unit number" (there is
unfortunately a lot of non-POLA in the exact numeric value of this
number, just live with it for now)

Managing the unit number space this way removes the need to use
rman(9) to do so in the drivers this greatly simplifies the code in
the drivers because even using rman(9) they still needed to manage
their dev_t's anyway.

I have taken the if_tun, if_tap, snp and nmdm drivers through the
mill, partly because they (ab)used makedev(), but mostly because
together they represent three different problems for device-cloning:

if_tun and snp is the plain case: just give me a device.

if_tap has two kinds of devices, with a flag for device type.

nmdm has paired devices (ala pty) can you can clone either of them.

1 files changed, 12 insertions, 18 deletions

diff --git a/sys/dev/snp/snp.c b/sys/dev/snp/snp.c
index 4c4115d..2c1c3c6 100644
--- a/sys/dev/snp/snp.c
+++ b/sys/dev/snp/snp.c
@@ -38,7 +38,6 @@ static	d_write_t	snpwrite;
 static	d_ioctl_t	snpioctl;
 static	d_poll_t	snppoll;
 
-#define CDEV_MAJOR 53
 static struct cdevsw snp_cdevsw = {
 	.d_open =	snpopen,
 	.d_close =	snpclose,
@@ -47,7 +46,7 @@ static struct cdevsw snp_cdevsw = {
 	.d_ioctl =	snpioctl,
 	.d_poll =	snppoll,
 	.d_name =	"snp",
-	.d_maj =	CDEV_MAJOR,
+	.d_flags =	D_PSEUDO,
 };
 
 static struct linesw snpdisc = {
@@ -101,10 +100,9 @@ static MALLOC_DEFINE(M_SNP, "snp", "Snoop device data");
  * module load time.
  */
 static int snooplinedisc;
-static udev_t snpbasedev = NOUDEV;
-
 
 static LIST_HEAD(, snoop) snp_sclist = LIST_HEAD_INITIALIZER(&snp_sclist);
+static struct clonedevs	  *snpclones;
 
 static struct tty	*snpdevtotty(dev_t dev);
 static void		snp_clone(void *arg, char *name,
@@ -384,9 +382,7 @@ snpopen(dev, flag, mode, td)
 	struct snoop *snp;
 
 	if (dev->si_drv1 == NULL) {
-		if (!(dev->si_flags & SI_NAMED))
-			make_dev(&snp_cdevsw, minor(dev), UID_ROOT, GID_WHEEL,
-			    0600, "snp%d", dev2unit(dev));
+		dev->si_flags &= ~SI_CHEAPCLONE;
 		dev->si_drv1 = snp = malloc(sizeof(*snp), M_SNP,
 		    M_WAITOK | M_ZERO);
 		snp->snp_unit = dev2unit(dev);
@@ -466,6 +462,7 @@ snpclose(dev, flags, fmt, td)
 	free(snp->snp_buf, M_SNP);
 	snp->snp_flags &= ~SNOOP_OPEN;
 	dev->si_drv1 = NULL;
+	destroy_dev(dev);
 
 	return (snp_detach(snp));
 }
@@ -608,20 +605,18 @@ snp_clone(arg, name, namelen, dev)
 	int namelen;
 	dev_t *dev;
 {
-	int u;
+	int u, i;
 
 	if (*dev != NODEV)
 		return;
 	if (dev_stdclone(name, NULL, "snp", &u) != 1)
 		return;
-	*dev = make_dev(&snp_cdevsw, unit2minor(u), UID_ROOT, GID_WHEEL, 0600,
-	    "snp%d", u);
-	if (snpbasedev == NOUDEV)
-		snpbasedev = (*dev)->si_udev;
-	else {
+	i = clone_create(&snpclones, &snp_cdevsw, &u, dev, 0);
+	if (i)
+		*dev = make_dev(&snp_cdevsw, unit2minor(u),
+		     UID_ROOT, GID_WHEEL, 0600, "snp%d", u);
+	if (*dev != NULL)
 		(*dev)->si_flags |= SI_CHEAPCLONE;
-		dev_depends(udev2dev(snpbasedev, 0), *dev);
-	}
 }
 
 static int
@@ -642,8 +637,7 @@ snp_modevent(mod, type, data)
 		if (!LIST_EMPTY(&snp_sclist))
 			return (EBUSY);
 		EVENTHANDLER_DEREGISTER(dev_clone, eh_tag);
-		if (snpbasedev != NOUDEV)
-			destroy_dev(udev2dev(snpbasedev, 0));
+		clone_cleanup(&snpclones);
 		ldisc_deregister(snooplinedisc);
 		break;
 	default:
@@ -657,4 +651,4 @@ static moduledata_t snp_mod = {
         snp_modevent,
         NULL
 };
-DECLARE_MODULE(snp, snp_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE + CDEV_MAJOR);
+DECLARE_MODULE(snp, snp_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);