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, 62 insertions, 101 deletions

diff --git a/sys/net/if_tun.c b/sys/net/if_tun.c
index 516d299..4a64da4 100644
--- a/sys/net/if_tun.c
+++ b/sys/net/if_tun.c
@@ -41,9 +41,7 @@
 #include <sys/uio.h>
 #include <sys/vnode.h>
 #include <sys/malloc.h>
-#include <machine/bus.h>	/* XXX Shouldn't really be required ! */
 #include <sys/random.h>
-#include <sys/rman.h>
 
 #include <net/if.h>
 #include <net/if_types.h>
@@ -53,17 +51,40 @@
 #include <netinet/in.h>
 #endif
 #include <net/bpf.h>
-#include <net/if_tunvar.h>
 #include <net/if_tun.h>
 
+#include <sys/queue.h>
+
+struct tun_softc {
+	TAILQ_ENTRY(tun_softc)	tun_list;
+	int			tun_unit;
+	dev_t			tun_dev;
+	u_short	tun_flags;		/* misc flags */
+#define	TUN_OPEN	0x0001
+#define	TUN_INITED	0x0002
+#define	TUN_RCOLL	0x0004
+#define	TUN_IASET	0x0008
+#define	TUN_DSTADDR	0x0010
+#define	TUN_LMODE	0x0020
+#define	TUN_RWAIT	0x0040
+#define	TUN_ASYNC	0x0080
+#define	TUN_IFHEAD	0x0100
+
+#define TUN_READY       (TUN_OPEN | TUN_INITED)
+
+	struct proc		*tun_proc;	/* Owning process */
+	struct	ifnet tun_if;		/* the interface */
+	struct  sigio *tun_sigio;	/* information for async I/O */
+	struct	selinfo	tun_rsel;	/* read select */
+};
+
 #define TUNDEBUG	if (tundebug) if_printf
 #define	TUNNAME		"tun"
 
 static MALLOC_DEFINE(M_TUN, TUNNAME, "Tunnel Interface");
 static int tundebug = 0;
-static struct tun_softc *tunhead = NULL;
-static struct rman tununits;
-static udev_t tunbasedev = NOUDEV;
+static struct clonedevs *tunclones;
+static TAILQ_HEAD(,tun_softc)	tunhead = TAILQ_HEAD_INITIALIZER(tunhead);
 SYSCTL_INT(_debug, OID_AUTO, if_tun_debug, CTLFLAG_RW, &tundebug, 0, "");
 
 static void	tunclone(void *arg, char *name, int namelen, dev_t *dev);
@@ -82,7 +103,6 @@ static d_write_t	tunwrite;
 static d_ioctl_t	tunioctl;
 static d_poll_t		tunpoll;
 
-#define CDEV_MAJOR 52
 static struct cdevsw tun_cdevsw = {
 	.d_open =	tunopen,
 	.d_close =	tunclose,
@@ -91,44 +111,32 @@ static struct cdevsw tun_cdevsw = {
 	.d_ioctl =	tunioctl,
 	.d_poll =	tunpoll,
 	.d_name =	TUNNAME,
-	.d_maj =	CDEV_MAJOR,
+	.d_flags =	D_PSEUDO,
 };
 
 static void
 tunclone(void *arg, char *name, int namelen, dev_t *dev)
 {
-	struct resource *r;
-	int err;
-	int u;
+	int u, i;
 
 	if (*dev != NODEV)
 		return;
 
 	if (strcmp(name, TUNNAME) == 0) {
-		r = rman_reserve_resource(&tununits, 0, IF_MAXUNIT, 1,
-		    RF_ALLOCATED | RF_ACTIVE, NULL);
-		u = rman_get_start(r);
-		err = rman_release_resource(r);
-		KASSERT(err == 0, ("Unexpected failure releasing resource"));
-		*dev = makedev(CDEV_MAJOR, unit2minor(u));
-		if ((*dev)->si_flags & SI_NAMED)
-			return;	/* Already make_dev()d */
+		u = -1;
 	} else if (dev_stdclone(name, NULL, TUNNAME, &u) != 1)
 		return;	/* Don't recognise the name */
-
-	*dev = make_dev(&tun_cdevsw, unit2minor(u),
-	    UID_ROOT, GID_WHEEL, 0600, "tun%d", u);
-
-	/*
-	 * All devices depend on tunbasedev so that we can simply
-	 * destroy_dev() this device at module unload time to get
-	 * rid of all our make_dev()d resources.
-	 */
-	if (tunbasedev == NOUDEV)
-		tunbasedev = (*dev)->si_udev;
-	else {
-		(*dev)->si_flags |= SI_CHEAPCLONE;
-		dev_depends(udev2dev(tunbasedev, 0), *dev);
+	if (u != -1 && u > IF_MAXUNIT)
+		return;	/* Unit number too high */
+
+	/* find any existing device, or allocate new unit number */
+	i = clone_create(&tunclones, &tun_cdevsw, &u, dev, 0);
+	if (i) {
+		/* No preexisting dev_t, create one */
+		*dev = make_dev(&tun_cdevsw, unit2minor(u),
+		    UID_UUCP, GID_DIALER, 0600, "tun%d", u);
+		if (*dev != NULL)
+			(*dev)->si_flags |= SI_CHEAPCLONE;
 	}
 }
 
@@ -138,57 +146,29 @@ tunmodevent(module_t mod, int type, void *data)
 	static eventhandler_tag tag;
 	struct tun_softc *tp;
 	dev_t dev;
-	int err;
 
 	switch (type) {
 	case MOD_LOAD:
 		tag = EVENTHANDLER_REGISTER(dev_clone, tunclone, 0, 1000);
 		if (tag == NULL)
 			return (ENOMEM);
-		tununits.rm_type = RMAN_ARRAY;
-		tununits.rm_descr = "open if_tun units";
-		err = rman_init(&tununits);
-		if (err != 0) {
-			EVENTHANDLER_DEREGISTER(dev_clone, tag);
-			return (err);
-		}
-		err = rman_manage_region(&tununits, 0, IF_MAXUNIT);
-		if (err != 0) {
-			printf("%s: tununits: rman_manage_region: Failed %d\n",
-			    TUNNAME, err);
-			rman_fini(&tununits);
-			EVENTHANDLER_DEREGISTER(dev_clone, tag);
-			return (err);
-		}
 		break;
 	case MOD_UNLOAD:
-		err = rman_fini(&tununits);
-		if (err != 0)
-			return (err);
 		EVENTHANDLER_DEREGISTER(dev_clone, tag);
 
-		while (tunhead != NULL) {
-			KASSERT((tunhead->tun_flags & TUN_OPEN) == 0,
+		while (!TAILQ_EMPTY(&tunhead)) {
+			tp = TAILQ_FIRST(&tunhead);
+			KASSERT((tp->tun_flags & TUN_OPEN) == 0,
 			    ("tununits is out of sync - unit %d",
-			    tunhead->tun_if.if_dunit));
-			tp = tunhead;
-			dev = makedev(tun_cdevsw.d_maj,
-			    unit2minor(tp->tun_if.if_dunit));
-			KASSERT(dev->si_drv1 == tp, ("Bad makedev result"));
-			tunhead = tp->next;
+			    tp->tun_if.if_dunit));
+			TAILQ_REMOVE(&tunhead, tp, tun_list);
+			dev = tp->tun_dev;
 			bpfdetach(&tp->tun_if);
 			if_detach(&tp->tun_if);
-			KASSERT(dev->si_flags & SI_NAMED, ("Missing make_dev"));
+			destroy_dev(dev);
 			free(tp, M_TUN);
 		}
-
-		/*
-		 * Destroying tunbasedev results in all of our make_dev()s
-		 * conveniently going away.
-		 */
-		if (tunbasedev != NOUDEV)
-			destroy_dev(udev2dev(tunbasedev, 0));
-
+		clone_cleanup(&tunclones);
 		break;
 	}
 	return 0;
@@ -222,14 +202,12 @@ tuncreate(dev_t dev)
 	struct tun_softc *sc;
 	struct ifnet *ifp;
 
-	if (!(dev->si_flags & SI_NAMED))
-		dev = make_dev(&tun_cdevsw, minor(dev),
-		    UID_UUCP, GID_DIALER, 0600, "tun%d", dev2unit(dev));
+	dev->si_flags &= ~SI_CHEAPCLONE;
 
 	MALLOC(sc, struct tun_softc *, sizeof(*sc), M_TUN, M_WAITOK | M_ZERO);
 	sc->tun_flags = TUN_INITED;
-	sc->next = tunhead;
-	tunhead = sc;
+	sc->tun_dev = dev;
+	TAILQ_INSERT_TAIL(&tunhead, sc, tun_list);
 
 	ifp = &sc->tun_if;
 	if_initname(ifp, TUNNAME, dev2unit(dev));
@@ -249,32 +227,21 @@ tuncreate(dev_t dev)
 static int
 tunopen(dev_t dev, int flag, int mode, struct thread *td)
 {
-	struct resource *r;
 	struct ifnet	*ifp;
 	struct tun_softc *tp;
-	int unit;
-
-	unit = dev2unit(dev);
-	if (unit > IF_MAXUNIT)
-		return (ENXIO);
-
-	r = rman_reserve_resource(&tununits, unit, unit, 1,
-	    RF_ALLOCATED | RF_ACTIVE, NULL);
-	if (r == NULL)
-		return (EBUSY);
-
-	dev->si_flags &= ~SI_CHEAPCLONE;
 
 	tp = dev->si_drv1;
 	if (!tp) {
 		tuncreate(dev);
 		tp = dev->si_drv1;
 	}
-	KASSERT(!(tp->tun_flags & TUN_OPEN), ("Resource & flags out-of-sync"));
-	tp->tun_unit = r;
-	tp->tun_pid = td->td_proc->p_pid;
-	ifp = &tp->tun_if;
+
+	if (tp->tun_proc != NULL && tp->tun_proc != td->td_proc)
+		return (EBUSY);
+	tp->tun_proc = td->td_proc;
+
 	tp->tun_flags |= TUN_OPEN;
+	ifp = &tp->tun_if;
 	TUNDEBUG(ifp, "open\n");
 
 	return (0);
@@ -290,14 +257,12 @@ tunclose(dev_t dev, int foo, int bar, struct thread *td)
 	struct tun_softc *tp;
 	struct ifnet *ifp;
 	int s;
-	int err;
 
 	tp = dev->si_drv1;
 	ifp = &tp->tun_if;
 
-	KASSERT(tp->tun_unit, ("Unit %d not marked open", tp->tun_if.if_dunit));
 	tp->tun_flags &= ~TUN_OPEN;
-	tp->tun_pid = 0;
+	tp->tun_proc = NULL;
 
 	/*
 	 * junk all pending output
@@ -325,11 +290,7 @@ tunclose(dev_t dev, int foo, int bar, struct thread *td)
 
 	funsetown(&tp->tun_sigio);
 	selwakeuppri(&tp->tun_rsel, PZERO + 1);
-
 	TUNDEBUG (ifp, "closed\n");
-	err = rman_release_resource(tp->tun_unit);
-	KASSERT(err == 0, ("Unit %d failed to release", tp->tun_if.if_dunit));
-
 	return (0);
 }
 
@@ -384,9 +345,9 @@ tunifioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
 	switch(cmd) {
 	case SIOCGIFSTATUS:
 		ifs = (struct ifstat *)data;
-		if (tp->tun_pid)
+		if (tp->tun_proc)
 			sprintf(ifs->ascii + strlen(ifs->ascii),
-			    "\tOpened by PID %d\n", tp->tun_pid);
+			    "\tOpened by PID %d\n", tp->tun_proc->p_pid);
 		break;
 	case SIOCSIFADDR:
 		error = tuninit(ifp);
@@ -573,7 +534,7 @@ tunioctl(dev_t dev, u_long cmd, caddr_t data, int flag, struct thread *td)
 		}
 		break;
 	case TUNSIFPID:
-		tp->tun_pid = curthread->td_proc->p_pid;
+		tp->tun_proc = curthread->td_proc;
 		break;
 	case FIONBIO:
 		break;