Revert r239178 and implement two new functions, namely

"device_free_softc()" and "device_claim_softc()",
to allow USB serial drivers refcounting the softc.
These functions are used to grab the softc from
auto-free and to free the softc back to the correct
malloc type, respectivly.

Discussed with:	jhb
MFC after:	2 weeks

25 files changed, 256 insertions, 227 deletions

diff --git a/sys/dev/usb/net/if_usie.c b/sys/dev/usb/net/if_usie.c
index 8b49d66..cdbdd6b 100644
--- a/sys/dev/usb/net/if_usie.c
+++ b/sys/dev/usb/net/if_usie.c
@@ -95,7 +95,7 @@ static const STRUCT_USB_HOST_ID usie_devs[] = {
 static device_probe_t usie_probe;
 static device_attach_t usie_attach;
 static device_detach_t usie_detach;
-static device_free_softc_t usie_free_softc;
+static void usie_free_softc(struct usie_softc *);
 
 static void usie_free(struct ucom_softc *);
 static void usie_uc_update_line_state(struct ucom_softc *, uint8_t);
@@ -191,7 +191,6 @@ static device_method_t usie_methods[] = {
 	DEVMETHOD(device_probe, usie_probe),
 	DEVMETHOD(device_attach, usie_attach),
 	DEVMETHOD(device_detach, usie_detach),
-	DEVMETHOD(device_free_softc, usie_free_softc),
 	DEVMETHOD_END
 };
 
@@ -488,27 +487,28 @@ usie_detach(device_t self)
 		usbd_transfer_unsetup(sc->sc_uc_xfer[x], USIE_UC_N_XFER);
 
 
+	device_claim_softc(self);
+
+	usie_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(usie);
 
 static void
-usie_free_softc(device_t dev, void *arg)
+usie_free_softc(struct usie_softc *sc)
 {
-	struct usie_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 usie_free(struct ucom_softc *ucom)
 {
-	usie_free_softc(NULL, ucom->sc_parent);
+	usie_free_softc(ucom->sc_parent);
 }
 
 static void
diff --git a/sys/dev/usb/net/uhso.c b/sys/dev/usb/net/uhso.c
index 073f6f6..979c118 100644
--- a/sys/dev/usb/net/uhso.c
+++ b/sys/dev/usb/net/uhso.c
@@ -474,13 +474,12 @@ static void uhso_if_rxflush(void *);
 static device_probe_t uhso_probe;
 static device_attach_t uhso_attach;
 static device_detach_t uhso_detach;
-static device_free_softc_t uhso_free_softc;
+static void uhso_free_softc(struct uhso_softc *);
 
 static device_method_t uhso_methods[] = {
 	DEVMETHOD(device_probe,		uhso_probe),
 	DEVMETHOD(device_attach,	uhso_attach),
 	DEVMETHOD(device_detach,	uhso_detach),
-	DEVMETHOD(device_free_softc,	uhso_free_softc),
 	{ 0, 0 }
 };
 
@@ -697,27 +696,28 @@ uhso_detach(device_t self)
 		usbd_transfer_unsetup(sc->sc_if_xfer, UHSO_IFNET_MAX);
 	}
 
+	device_claim_softc(self);
+
+	uhso_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(uhso);
 
 static void
-uhso_free_softc(device_t dev, void *arg)
+uhso_free_softc(struct uhso_softc *sc)
 {
-	struct uhso_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 uhso_free(struct ucom_softc *ucom)
 {
-	uhso_free_softc(NULL, ucom->sc_parent);
+	uhso_free_softc(ucom->sc_parent);
 }
 
 static void
diff --git a/sys/dev/usb/serial/u3g.c b/sys/dev/usb/serial/u3g.c
index 50af2d5..eb6c4d0 100644
--- a/sys/dev/usb/serial/u3g.c
+++ b/sys/dev/usb/serial/u3g.c
@@ -118,7 +118,7 @@ struct u3g_softc {
 static device_probe_t u3g_probe;
 static device_attach_t u3g_attach;
 static device_detach_t u3g_detach;
-static device_free_softc_t u3g_free_softc;
+static void u3g_free_softc(struct u3g_softc *);
 
 static usb_callback_t u3g_write_callback;
 static usb_callback_t u3g_read_callback;
@@ -169,7 +169,6 @@ static device_method_t u3g_methods[] = {
 	DEVMETHOD(device_probe, u3g_probe),
 	DEVMETHOD(device_attach, u3g_attach),
 	DEVMETHOD(device_detach, u3g_detach),
-	DEVMETHOD(device_free_softc, u3g_free_softc),
 	DEVMETHOD_END
 };
 
@@ -898,27 +897,28 @@ u3g_detach(device_t dev)
 	for (subunit = 0; subunit != U3G_MAXPORTS; subunit++)
 		usbd_transfer_unsetup(sc->sc_xfer[subunit], U3G_N_TRANSFER);
 
+	device_claim_softc(dev);
+
+	u3g_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(u3g);
 
 static void
-u3g_free_softc(device_t dev, void *arg)
+u3g_free_softc(struct u3g_softc *sc)
 {
-	struct u3g_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 u3g_free(struct ucom_softc *ucom)
 {
-	u3g_free_softc(NULL, ucom->sc_parent);
+	u3g_free_softc(ucom->sc_parent);
 }
 
 static void
diff --git a/sys/dev/usb/serial/uark.c b/sys/dev/usb/serial/uark.c
index eef7ac2..f0737f2 100644
--- a/sys/dev/usb/serial/uark.c
+++ b/sys/dev/usb/serial/uark.c
@@ -99,7 +99,7 @@ struct uark_softc {
 static device_probe_t uark_probe;
 static device_attach_t uark_attach;
 static device_detach_t uark_detach;
-static device_free_softc_t uark_free_softc;
+static void uark_free_softc(struct uark_softc *);
 
 static usb_callback_t uark_bulk_write_callback;
 static usb_callback_t uark_bulk_read_callback;
@@ -157,7 +157,6 @@ static device_method_t uark_methods[] = {
 	DEVMETHOD(device_probe, uark_probe),
 	DEVMETHOD(device_attach, uark_attach),
 	DEVMETHOD(device_detach, uark_detach),
-	DEVMETHOD(device_free_softc, uark_free_softc),
 	DEVMETHOD_END
 };
 
@@ -248,27 +247,28 @@ uark_detach(device_t dev)
 	ucom_detach(&sc->sc_super_ucom, &sc->sc_ucom);
 	usbd_transfer_unsetup(sc->sc_xfer, UARK_N_TRANSFER);
 
+	device_claim_softc(dev);
+
+	uark_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(uark);
 
 static void
-uark_free_softc(device_t dev, void *arg)
+uark_free_softc(struct uark_softc *sc)
 {
-	struct uark_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 uark_free(struct ucom_softc *ucom)
 {
-	uark_free_softc(NULL, ucom->sc_parent);
+	uark_free_softc(ucom->sc_parent);
 }
 
 static void
diff --git a/sys/dev/usb/serial/ubsa.c b/sys/dev/usb/serial/ubsa.c
index f434f48..0951626 100644
--- a/sys/dev/usb/serial/ubsa.c
+++ b/sys/dev/usb/serial/ubsa.c
@@ -176,7 +176,7 @@ struct ubsa_softc {
 static device_probe_t ubsa_probe;
 static device_attach_t ubsa_attach;
 static device_detach_t ubsa_detach;
-static device_free_softc_t ubsa_free_softc;
+static void ubsa_free_softc(struct ubsa_softc *);
 
 static usb_callback_t ubsa_write_callback;
 static usb_callback_t ubsa_read_callback;
@@ -265,7 +265,6 @@ static device_method_t ubsa_methods[] = {
 	DEVMETHOD(device_probe, ubsa_probe),
 	DEVMETHOD(device_attach, ubsa_attach),
 	DEVMETHOD(device_detach, ubsa_detach),
-	DEVMETHOD(device_free_softc, ubsa_free_softc),
 	DEVMETHOD_END
 };
 
@@ -354,27 +353,28 @@ ubsa_detach(device_t dev)
 	ucom_detach(&sc->sc_super_ucom, &sc->sc_ucom);
 	usbd_transfer_unsetup(sc->sc_xfer, UBSA_N_TRANSFER);
 
+	device_claim_softc(dev);
+
+	ubsa_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(ubsa);
 
 static void
-ubsa_free_softc(device_t dev, void *arg)
+ubsa_free_softc(struct ubsa_softc *sc)
 {
-	struct ubsa_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 ubsa_free(struct ucom_softc *ucom)
 {
-	ubsa_free_softc(NULL, ucom->sc_parent);
+	ubsa_free_softc(ucom->sc_parent);
 }
 
 static void
diff --git a/sys/dev/usb/serial/ubser.c b/sys/dev/usb/serial/ubser.c
index 9577a59..dae35ab 100644
--- a/sys/dev/usb/serial/ubser.c
+++ b/sys/dev/usb/serial/ubser.c
@@ -148,7 +148,7 @@ struct ubser_softc {
 static device_probe_t ubser_probe;
 static device_attach_t ubser_attach;
 static device_detach_t ubser_detach;
-static device_free_softc_t ubser_free_softc;
+static void ubser_free_softc(struct ubser_softc *);
 
 static usb_callback_t ubser_write_callback;
 static usb_callback_t ubser_read_callback;
@@ -201,7 +201,6 @@ static device_method_t ubser_methods[] = {
 	DEVMETHOD(device_probe, ubser_probe),
 	DEVMETHOD(device_attach, ubser_attach),
 	DEVMETHOD(device_detach, ubser_detach),
-	DEVMETHOD(device_free_softc, ubser_free_softc),
 	DEVMETHOD_END
 };
 
@@ -321,27 +320,28 @@ ubser_detach(device_t dev)
 	ucom_detach(&sc->sc_super_ucom, sc->sc_ucom);
 	usbd_transfer_unsetup(sc->sc_xfer, UBSER_N_TRANSFER);
 
+	device_claim_softc(dev);
+
+	ubser_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(ubser);
 
 static void
-ubser_free_softc(device_t dev, void *arg)
+ubser_free_softc(struct ubser_softc *sc)
 {
-	struct ubser_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 ubser_free(struct ucom_softc *ucom)
 {
-	ubser_free_softc(NULL, ucom->sc_parent);
+	ubser_free_softc(ucom->sc_parent);
 }
 
 static int
diff --git a/sys/dev/usb/serial/uchcom.c b/sys/dev/usb/serial/uchcom.c
index e62a13c..cdddfb0 100644
--- a/sys/dev/usb/serial/uchcom.c
+++ b/sys/dev/usb/serial/uchcom.c
@@ -235,7 +235,7 @@ static void	uchcom_poll(struct ucom_softc *ucom);
 static device_probe_t uchcom_probe;
 static device_attach_t uchcom_attach;
 static device_detach_t uchcom_detach;
-static device_free_softc_t uchcom_free_softc;
+static void uchcom_free_softc(struct uchcom_softc *);
 
 static usb_callback_t uchcom_intr_callback;
 static usb_callback_t uchcom_write_callback;
@@ -376,27 +376,28 @@ uchcom_detach(device_t dev)
 	ucom_detach(&sc->sc_super_ucom, &sc->sc_ucom);
 	usbd_transfer_unsetup(sc->sc_xfer, UCHCOM_N_TRANSFER);
 
+	device_claim_softc(dev);
+
+	uchcom_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(uchcom);
 
 static void
-uchcom_free_softc(device_t dev, void *arg)
+uchcom_free_softc(struct uchcom_softc *sc)
 {
-	struct uchcom_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 uchcom_free(struct ucom_softc *ucom)
 {
-	uchcom_free_softc(NULL, ucom->sc_parent);
+	uchcom_free_softc(ucom->sc_parent);
 }
 
 /* ----------------------------------------------------------------------
@@ -864,7 +865,6 @@ static device_method_t uchcom_methods[] = {
 	DEVMETHOD(device_probe, uchcom_probe),
 	DEVMETHOD(device_attach, uchcom_attach),
 	DEVMETHOD(device_detach, uchcom_detach),
-	DEVMETHOD(device_free_softc, uchcom_free_softc),
 	DEVMETHOD_END
 };
 
diff --git a/sys/dev/usb/serial/ucycom.c b/sys/dev/usb/serial/ucycom.c
index 80aa57e..7536a02 100644
--- a/sys/dev/usb/serial/ucycom.c
+++ b/sys/dev/usb/serial/ucycom.c
@@ -110,7 +110,7 @@ struct ucycom_softc {
 static device_probe_t ucycom_probe;
 static device_attach_t ucycom_attach;
 static device_detach_t ucycom_detach;
-static device_free_softc_t ucycom_free_softc;
+static void ucycom_free_softc(struct ucycom_softc *);
 
 static usb_callback_t ucycom_ctrl_write_callback;
 static usb_callback_t ucycom_intr_read_callback;
@@ -163,7 +163,6 @@ static device_method_t ucycom_methods[] = {
 	DEVMETHOD(device_probe, ucycom_probe),
 	DEVMETHOD(device_attach, ucycom_attach),
 	DEVMETHOD(device_detach, ucycom_detach),
-	DEVMETHOD(device_free_softc, ucycom_free_softc),
 	DEVMETHOD_END
 };
 
@@ -299,27 +298,28 @@ ucycom_detach(device_t dev)
 	ucom_detach(&sc->sc_super_ucom, &sc->sc_ucom);
 	usbd_transfer_unsetup(sc->sc_xfer, UCYCOM_N_TRANSFER);
 
+	device_claim_softc(dev);
+
+	ucycom_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(ucycom);
 
 static void
-ucycom_free_softc(device_t dev, void *arg)
+ucycom_free_softc(struct ucycom_softc *sc)
 {
-	struct ucycom_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 ucycom_free(struct ucom_softc *ucom)
 {
-	ucycom_free_softc(NULL, ucom->sc_parent);
+	ucycom_free_softc(ucom->sc_parent);
 }
 
 static void
diff --git a/sys/dev/usb/serial/ufoma.c b/sys/dev/usb/serial/ufoma.c
index 0e9adf5..d929f86 100644
--- a/sys/dev/usb/serial/ufoma.c
+++ b/sys/dev/usb/serial/ufoma.c
@@ -202,7 +202,7 @@ struct ufoma_softc {
 static device_probe_t ufoma_probe;
 static device_attach_t ufoma_attach;
 static device_detach_t ufoma_detach;
-static device_free_softc_t ufoma_free_softc;
+static void ufoma_free_softc(struct ufoma_softc *);
 
 static usb_callback_t ufoma_ctrl_read_callback;
 static usb_callback_t ufoma_ctrl_write_callback;
@@ -313,7 +313,6 @@ static device_method_t ufoma_methods[] = {
 	DEVMETHOD(device_probe, ufoma_probe),
 	DEVMETHOD(device_attach, ufoma_attach),
 	DEVMETHOD(device_detach, ufoma_detach),
-	DEVMETHOD(device_free_softc, ufoma_free_softc),
 	DEVMETHOD_END
 };
 
@@ -498,27 +497,28 @@ ufoma_detach(device_t dev)
 	}
 	cv_destroy(&sc->sc_cv);
 
+	device_claim_softc(dev);
+
+	ufoma_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(ufoma);
 
 static void
-ufoma_free_softc(device_t dev, void *arg)
+ufoma_free_softc(struct ufoma_softc *sc)
 {
-	struct ufoma_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 ufoma_free(struct ucom_softc *ucom)
 {
-	ufoma_free_softc(NULL, ucom->sc_parent);
+	ufoma_free_softc(ucom->sc_parent);
 }
 
 static void *
diff --git a/sys/dev/usb/serial/uftdi.c b/sys/dev/usb/serial/uftdi.c
index 7ffd4f2..0a7f0a2 100644
--- a/sys/dev/usb/serial/uftdi.c
+++ b/sys/dev/usb/serial/uftdi.c
@@ -125,7 +125,7 @@ struct uftdi_param_config {
 static device_probe_t uftdi_probe;
 static device_attach_t uftdi_attach;
 static device_detach_t uftdi_detach;
-static device_free_softc_t uftdi_free_softc;
+static void uftdi_free_softc(struct uftdi_softc *);
 
 static usb_callback_t uftdi_write_callback;
 static usb_callback_t uftdi_read_callback;
@@ -190,7 +190,6 @@ static device_method_t uftdi_methods[] = {
 	DEVMETHOD(device_probe, uftdi_probe),
 	DEVMETHOD(device_attach, uftdi_attach),
 	DEVMETHOD(device_detach, uftdi_detach),
-	DEVMETHOD(device_free_softc, uftdi_free_softc),
 	DEVMETHOD_END
 };
 
@@ -960,27 +959,28 @@ uftdi_detach(device_t dev)
 	ucom_detach(&sc->sc_super_ucom, &sc->sc_ucom);
 	usbd_transfer_unsetup(sc->sc_xfer, UFTDI_N_TRANSFER);
 
+	device_claim_softc(dev);
+
+	uftdi_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(uftdi);
 
 static void
-uftdi_free_softc(device_t dev, void *arg)
+uftdi_free_softc(struct uftdi_softc *sc)
 {
-	struct uftdi_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 uftdi_free(struct ucom_softc *ucom)
 {
-	uftdi_free_softc(NULL, ucom->sc_parent);
+	uftdi_free_softc(ucom->sc_parent);
 }
 
 static void
diff --git a/sys/dev/usb/serial/ugensa.c b/sys/dev/usb/serial/ugensa.c
index 201a75e..5d6785d 100644
--- a/sys/dev/usb/serial/ugensa.c
+++ b/sys/dev/usb/serial/ugensa.c
@@ -94,7 +94,7 @@ struct ugensa_softc {
 static device_probe_t ugensa_probe;
 static device_attach_t ugensa_attach;
 static device_detach_t ugensa_detach;
-static device_free_softc_t ugensa_free_softc;
+static void ugensa_free_softc(struct ugensa_softc *);
 
 static usb_callback_t ugensa_bulk_write_callback;
 static usb_callback_t ugensa_bulk_read_callback;
@@ -141,7 +141,6 @@ static device_method_t ugensa_methods[] = {
 	DEVMETHOD(device_probe, ugensa_probe),
 	DEVMETHOD(device_attach, ugensa_attach),
 	DEVMETHOD(device_detach, ugensa_detach),
-	DEVMETHOD(device_free_softc, ugensa_free_softc),
 	DEVMETHOD_END
 };
 
@@ -272,27 +271,28 @@ ugensa_detach(device_t dev)
 		usbd_transfer_unsetup(sc->sc_sub[x].sc_xfer, UGENSA_N_TRANSFER);
 	}
 
+	device_claim_softc(dev);
+
+	ugensa_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(ugensa);
 
 static void
-ugensa_free_softc(device_t dev, void *arg)
+ugensa_free_softc(struct ugensa_softc *sc)
 {
-	struct ugensa_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 ugensa_free(struct ucom_softc *ucom)
 {
-	ugensa_free_softc(NULL, ucom->sc_parent);
+	ugensa_free_softc(ucom->sc_parent);
 }
 
 static void
diff --git a/sys/dev/usb/serial/uipaq.c b/sys/dev/usb/serial/uipaq.c
index 31d2595..f9e54f8 100644
--- a/sys/dev/usb/serial/uipaq.c
+++ b/sys/dev/usb/serial/uipaq.c
@@ -103,7 +103,7 @@ struct uipaq_softc {
 static device_probe_t uipaq_probe;
 static device_attach_t uipaq_attach;
 static device_detach_t uipaq_detach;
-static device_free_softc_t uipaq_free_softc;
+static void uipaq_free_softc(struct uipaq_softc *);
 
 static usb_callback_t uipaq_write_callback;
 static usb_callback_t uipaq_read_callback;
@@ -1073,7 +1073,6 @@ static device_method_t uipaq_methods[] = {
 	DEVMETHOD(device_probe, uipaq_probe),
 	DEVMETHOD(device_attach, uipaq_attach),
 	DEVMETHOD(device_detach, uipaq_detach),
-	DEVMETHOD(device_free_softc, uipaq_free_softc),
 	DEVMETHOD_END
 };
 
@@ -1182,27 +1181,28 @@ uipaq_detach(device_t dev)
 	ucom_detach(&sc->sc_super_ucom, &sc->sc_ucom);
 	usbd_transfer_unsetup(sc->sc_xfer, UIPAQ_N_TRANSFER);
 
+	device_claim_softc(dev);
+
+	uipaq_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(uipaq);
 
 static void
-uipaq_free_softc(device_t dev, void *arg)
+uipaq_free_softc(struct uipaq_softc *sc)
 {
-	struct uipaq_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 uipaq_free(struct ucom_softc *ucom)
 {
-	uipaq_free_softc(NULL, ucom->sc_parent);
+	uipaq_free_softc(ucom->sc_parent);
 }
 
 static void
diff --git a/sys/dev/usb/serial/umcs.c b/sys/dev/usb/serial/umcs.c
index 038db29..2e09ba6 100644
--- a/sys/dev/usb/serial/umcs.c
+++ b/sys/dev/usb/serial/umcs.c
@@ -176,7 +176,7 @@ static void umcs7840_poll(struct ucom_softc *ucom);
 static device_probe_t umcs7840_probe;
 static device_attach_t umcs7840_attach;
 static device_detach_t umcs7840_detach;
-static device_free_softc_t umcs7840_free_softc;
+static void umcs7840_free_softc(struct umcs7840_softc *);
 
 static usb_callback_t umcs7840_intr_callback;
 static usb_callback_t umcs7840_read_callback1;
@@ -265,7 +265,6 @@ static device_method_t umcs7840_methods[] = {
 	DEVMETHOD(device_probe, umcs7840_probe),
 	DEVMETHOD(device_attach, umcs7840_attach),
 	DEVMETHOD(device_detach, umcs7840_detach),
-	DEVMETHOD(device_free_softc, umcs7840_free_softc),
 	DEVMETHOD_END
 };
 
@@ -413,27 +412,28 @@ umcs7840_detach(device_t dev)
 		usbd_transfer_unsetup(sc->sc_ports[sc->sc_ucom[subunit].sc_portno].sc_xfer, UMCS7840_N_TRANSFERS);
 	usbd_transfer_unsetup(&sc->sc_intr_xfer, 1);
 
+	device_claim_softc(dev);
+
+	umcs7840_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(umcs7840);
 
 static void
-umcs7840_free_softc(device_t dev, void *arg)
+umcs7840_free_softc(struct umcs7840_softc *sc)
 {
-	struct umcs7840_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 umcs7840_free(struct ucom_softc *ucom)
 {
-	umcs7840_free_softc(NULL, ucom->sc_parent);
+	umcs7840_free_softc(ucom->sc_parent);
 }
 
 static void
diff --git a/sys/dev/usb/serial/umct.c b/sys/dev/usb/serial/umct.c
index e24fbc8..d8fad98 100644
--- a/sys/dev/usb/serial/umct.c
+++ b/sys/dev/usb/serial/umct.c
@@ -122,7 +122,7 @@ struct umct_softc {
 static device_probe_t umct_probe;
 static device_attach_t umct_attach;
 static device_detach_t umct_detach;
-static device_free_softc_t umct_free_softc;
+static void umct_free_softc(struct umct_softc *);
 
 static usb_callback_t umct_intr_callback;
 static usb_callback_t umct_intr_callback_sub;
@@ -206,7 +206,6 @@ static device_method_t umct_methods[] = {
 	DEVMETHOD(device_probe, umct_probe),
 	DEVMETHOD(device_attach, umct_attach),
 	DEVMETHOD(device_detach, umct_detach),
-	DEVMETHOD(device_free_softc, umct_free_softc),
 	DEVMETHOD_END
 };
 
@@ -314,27 +313,28 @@ umct_detach(device_t dev)
 	ucom_detach(&sc->sc_super_ucom, &sc->sc_ucom);
 	usbd_transfer_unsetup(sc->sc_xfer, UMCT_N_TRANSFER);
 
+	device_claim_softc(dev);
+
+	umct_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(umct);
 
 static void
-umct_free_softc(device_t dev, void *arg)
+umct_free_softc(struct umct_softc *sc)
 {
-	struct umct_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 umct_free(struct ucom_softc *ucom)
 {
-	umct_free_softc(NULL, ucom->sc_parent);
+	umct_free_softc(ucom->sc_parent);
 }
 
 static void
diff --git a/sys/dev/usb/serial/umodem.c b/sys/dev/usb/serial/umodem.c
index 72e60a9..d0dc364 100644
--- a/sys/dev/usb/serial/umodem.c
+++ b/sys/dev/usb/serial/umodem.c
@@ -178,7 +178,7 @@ struct umodem_softc {
 static device_probe_t umodem_probe;
 static device_attach_t umodem_attach;
 static device_detach_t umodem_detach;
-static device_free_softc_t umodem_free_softc;
+static void umodem_free_softc(struct umodem_softc *);
 
 static usb_callback_t umodem_intr_callback;
 static usb_callback_t umodem_write_callback;
@@ -259,7 +259,6 @@ static device_method_t umodem_methods[] = {
 	DEVMETHOD(device_probe, umodem_probe),
 	DEVMETHOD(device_attach, umodem_attach),
 	DEVMETHOD(device_detach, umodem_detach),
-	DEVMETHOD(device_free_softc, umodem_free_softc),
 	DEVMETHOD_END
 };
 
@@ -881,27 +880,28 @@ umodem_detach(device_t dev)
 	ucom_detach(&sc->sc_super_ucom, &sc->sc_ucom);
 	usbd_transfer_unsetup(sc->sc_xfer, UMODEM_N_TRANSFER);
 
+	device_claim_softc(dev);
+
+	umodem_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(umodem);
 
 static void
-umodem_free_softc(device_t dev, void *arg)
+umodem_free_softc(struct umodem_softc *sc)
 {
-	struct umodem_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 umodem_free(struct ucom_softc *ucom)
 {
-	umodem_free_softc(NULL, ucom->sc_parent);
+	umodem_free_softc(ucom->sc_parent);
 }
 
 static void
diff --git a/sys/dev/usb/serial/umoscom.c b/sys/dev/usb/serial/umoscom.c
index bec0c45..c51627d 100644
--- a/sys/dev/usb/serial/umoscom.c
+++ b/sys/dev/usb/serial/umoscom.c
@@ -189,7 +189,7 @@ struct umoscom_softc {
 static device_probe_t umoscom_probe;
 static device_attach_t umoscom_attach;
 static device_detach_t umoscom_detach;
-static device_free_softc_t umoscom_free_softc;
+static void umoscom_free_softc(struct umoscom_softc *);
 
 static usb_callback_t umoscom_write_callback;
 static usb_callback_t umoscom_read_callback;
@@ -267,7 +267,6 @@ static device_method_t umoscom_methods[] = {
 	DEVMETHOD(device_probe, umoscom_probe),
 	DEVMETHOD(device_attach, umoscom_attach),
 	DEVMETHOD(device_detach, umoscom_detach),
-	DEVMETHOD(device_free_softc, umoscom_free_softc),
 	DEVMETHOD_END
 };
 
@@ -360,27 +359,28 @@ umoscom_detach(device_t dev)
 	ucom_detach(&sc->sc_super_ucom, &sc->sc_ucom);
 	usbd_transfer_unsetup(sc->sc_xfer, UMOSCOM_N_TRANSFER);
 
+	device_claim_softc(dev);
+
+	umoscom_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(umoscom);
 
 static void
-umoscom_free_softc(device_t dev, void *arg)
+umoscom_free_softc(struct umoscom_softc *sc)
 {
-	struct umoscom_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 umoscom_free(struct ucom_softc *ucom)
 {
-	umoscom_free_softc(NULL, ucom->sc_parent);
+	umoscom_free_softc(ucom->sc_parent);
 }
 
 static void
diff --git a/sys/dev/usb/serial/uplcom.c b/sys/dev/usb/serial/uplcom.c
index 11d6810..4549bad 100644
--- a/sys/dev/usb/serial/uplcom.c
+++ b/sys/dev/usb/serial/uplcom.c
@@ -193,7 +193,7 @@ static void	uplcom_poll(struct ucom_softc *ucom);
 static device_probe_t uplcom_probe;
 static device_attach_t uplcom_attach;
 static device_detach_t uplcom_detach;
-static device_free_softc_t uplcom_free_softc;
+static void uplcom_free_softc(struct uplcom_softc *);
 
 static usb_callback_t uplcom_intr_callback;
 static usb_callback_t uplcom_write_callback;
@@ -318,7 +318,6 @@ static device_method_t uplcom_methods[] = {
 	DEVMETHOD(device_probe, uplcom_probe),
 	DEVMETHOD(device_attach, uplcom_attach),
 	DEVMETHOD(device_detach, uplcom_detach),
-	DEVMETHOD(device_free_softc, uplcom_free_softc),
 	DEVMETHOD_END
 };
 
@@ -471,27 +470,28 @@ uplcom_detach(device_t dev)
 	ucom_detach(&sc->sc_super_ucom, &sc->sc_ucom);
 	usbd_transfer_unsetup(sc->sc_xfer, UPLCOM_N_TRANSFER);
 
+	device_claim_softc(dev);
+
+	uplcom_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(uplcom);
 
 static void
-uplcom_free_softc(device_t dev, void *arg)
+uplcom_free_softc(struct uplcom_softc *sc)
 {
-	struct uplcom_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 uplcom_free(struct ucom_softc *ucom)
 {
-	uplcom_free_softc(NULL, ucom->sc_parent);
+	uplcom_free_softc(ucom->sc_parent);
 }
 
 static usb_error_t
diff --git a/sys/dev/usb/serial/usb_serial.c b/sys/dev/usb/serial/usb_serial.c
index 78ab671..c3161d2 100644
--- a/sys/dev/usb/serial/usb_serial.c
+++ b/sys/dev/usb/serial/usb_serial.c
@@ -284,11 +284,14 @@ ucom_attach(struct ucom_super_softc *ssc, struct ucom_softc *sc,
 		return (error);
 	}
 	ssc->sc_subunits = subunits;
+	ssc->sc_flag = UCOM_FLAG_ATTACHED |
+	    UCOM_FLAG_FREE_UNIT;
 
-	if (callback->ucom_free == NULL) {
-		ssc->sc_wait_refs = 1;
-		ucom_ref(ssc);
-	}
+	if (callback->ucom_free == NULL)
+		ssc->sc_flag |= UCOM_FLAG_WAIT_REFS;
+
+	/* increment reference count */
+	ucom_ref(ssc);
 
 	for (subunit = 0; subunit < ssc->sc_subunits; subunit++) {
 		sc[subunit].sc_subunit = subunit;
@@ -316,15 +319,15 @@ ucom_attach(struct ucom_super_softc *ssc, struct ucom_softc *sc,
 }
 
 /*
- * NOTE: the following function will do nothing if
- * the structure pointed to by "ssc" and "sc" is zero.
+ * The following function will do nothing if the structure pointed to
+ * by "ssc" and "sc" is zero or has already been detached.
  */
 void
 ucom_detach(struct ucom_super_softc *ssc, struct ucom_softc *sc)
 {
 	int subunit;
 
-	if (ssc->sc_subunits == 0)
+	if (!(ssc->sc_flag & UCOM_FLAG_ATTACHED))
 		return;		/* not initialized */
 
 	if (ssc->sc_sysctl_ttyname != NULL) {
@@ -350,17 +353,20 @@ ucom_detach(struct ucom_super_softc *ssc, struct ucom_softc *sc)
 	}
 	usb_proc_free(&ssc->sc_tq);
 
-	if (ssc->sc_wait_refs != 0) {
-		ucom_unref(ssc);
+	ucom_unref(ssc);
+
+	if (ssc->sc_flag & UCOM_FLAG_WAIT_REFS)
 		ucom_drain(ssc);
-	}
+
+	/* make sure we don't detach twice */
+	ssc->sc_flag &= ~UCOM_FLAG_ATTACHED;
 }
 
 void
 ucom_drain(struct ucom_super_softc *ssc)
 {
 	mtx_lock(&ucom_mtx);
-	while (ssc->sc_refs >= 2) {
+	while (ssc->sc_refs > 0) {
 		printf("ucom: Waiting for a TTY device to close.\n");
 		usb_pause_mtx(&ucom_mtx, hz);
 	}
@@ -1513,6 +1519,24 @@ ucom_ref(struct ucom_super_softc *ssc)
 }
 
 /*------------------------------------------------------------------------*
+ *	ucom_free_unit
+ *
+ * This function will free the super UCOM's allocated unit
+ * number. This function can be called on a zero-initialized
+ * structure. This function can be called multiple times.
+ *------------------------------------------------------------------------*/
+static void
+ucom_free_unit(struct ucom_super_softc *ssc)
+{
+	if (!(ssc->sc_flag & UCOM_FLAG_FREE_UNIT))
+		return;
+
+	ucom_unit_free(ssc->sc_unit);
+
+	ssc->sc_flag &= ~UCOM_FLAG_FREE_UNIT;
+}
+
+/*------------------------------------------------------------------------*
  *	ucom_unref
  *
  * This function will decrement the super UCOM reference count.
@@ -1525,21 +1549,15 @@ int
 ucom_unref(struct ucom_super_softc *ssc)
 {
 	int retval;
-	int free_unit;
 
 	mtx_lock(&ucom_mtx);
 	retval = (ssc->sc_refs < 2);
-	free_unit = (ssc->sc_refs == 1);
 	ssc->sc_refs--;
 	mtx_unlock(&ucom_mtx);
 
-	/*
-	 * This function might be called when the "ssc" is only zero
-	 * initialized and in that case the unit number should not be
-	 * freed.
-	 */
-	if (free_unit)
-		ucom_unit_free(ssc->sc_unit);
+	if (retval)
+		ucom_free_unit(ssc);
+
 	return (retval);
 }
 
diff --git a/sys/dev/usb/serial/usb_serial.h b/sys/dev/usb/serial/usb_serial.h
index 4cacd9c..7d72adf 100644
--- a/sys/dev/usb/serial/usb_serial.h
+++ b/sys/dev/usb/serial/usb_serial.h
@@ -137,7 +137,7 @@ struct ucom_super_softc {
 	int sc_unit;
 	int sc_subunits;
 	int sc_refs;
-	int sc_wait_refs;
+	int sc_flag;	/* see UCOM_FLAG_XXX */
 	struct sysctl_oid *sc_sysctl_ttyname;
 	struct sysctl_oid *sc_sysctl_ttyports;
 	char sc_ttyname[16];
@@ -178,6 +178,8 @@ struct ucom_softc {
 #define	UCOM_FLAG_LL_READY	0x20	/* set if low layer is ready */
 #define	UCOM_FLAG_HL_READY	0x40	/* set if high layer is ready */
 #define	UCOM_FLAG_CONSOLE	0x80	/* set if device is a console */
+#define	UCOM_FLAG_WAIT_REFS   0x0100	/* set if we must wait for refs */
+#define	UCOM_FLAG_FREE_UNIT   0x0200	/* set if we must free the unit */
 	uint8_t	sc_lsr;
 	uint8_t	sc_msr;
 	uint8_t	sc_mcr;
diff --git a/sys/dev/usb/serial/uslcom.c b/sys/dev/usb/serial/uslcom.c
index e2003ed..d6fa4ec 100644
--- a/sys/dev/usb/serial/uslcom.c
+++ b/sys/dev/usb/serial/uslcom.c
@@ -146,7 +146,7 @@ struct uslcom_softc {
 static device_probe_t uslcom_probe;
 static device_attach_t uslcom_attach;
 static device_detach_t uslcom_detach;
-static device_free_softc_t uslcom_free_softc;
+static void uslcom_free_softc(struct uslcom_softc *);
 
 static usb_callback_t uslcom_write_callback;
 static usb_callback_t uslcom_read_callback;
@@ -331,7 +331,6 @@ static device_method_t uslcom_methods[] = {
 	DEVMETHOD(device_probe, uslcom_probe),
 	DEVMETHOD(device_attach, uslcom_attach),
 	DEVMETHOD(device_detach, uslcom_detach),
-	DEVMETHOD(device_free_softc, uslcom_free_softc),
 	DEVMETHOD_END
 };
 
@@ -435,27 +434,28 @@ uslcom_detach(device_t dev)
 
 	usb_callout_drain(&sc->sc_watchdog);
 
+	device_claim_softc(dev);
+
+	uslcom_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(uslcom);
 
 static void
-uslcom_free_softc(device_t dev, void *arg)
+uslcom_free_softc(struct uslcom_softc *sc)
 {
-	struct uslcom_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 uslcom_free(struct ucom_softc *ucom)
 {
-	uslcom_free_softc(NULL, ucom->sc_parent);
+	uslcom_free_softc(ucom->sc_parent);
 }
 
 static void
diff --git a/sys/dev/usb/serial/uvisor.c b/sys/dev/usb/serial/uvisor.c
index 4f3426b..793e805 100644
--- a/sys/dev/usb/serial/uvisor.c
+++ b/sys/dev/usb/serial/uvisor.c
@@ -189,7 +189,7 @@ struct uvisor_softc {
 static device_probe_t uvisor_probe;
 static device_attach_t uvisor_attach;
 static device_detach_t uvisor_detach;
-static device_free_softc_t uvisor_free_softc;
+static void uvisor_free_softc(struct uvisor_softc *);
 
 static usb_callback_t uvisor_write_callback;
 static usb_callback_t uvisor_read_callback;
@@ -240,7 +240,6 @@ static device_method_t uvisor_methods[] = {
 	DEVMETHOD(device_probe, uvisor_probe),
 	DEVMETHOD(device_attach, uvisor_attach),
 	DEVMETHOD(device_detach, uvisor_detach),
-	DEVMETHOD(device_free_softc, uvisor_free_softc),
 	DEVMETHOD_END
 };
 
@@ -371,27 +370,28 @@ uvisor_detach(device_t dev)
 	ucom_detach(&sc->sc_super_ucom, &sc->sc_ucom);
 	usbd_transfer_unsetup(sc->sc_xfer, UVISOR_N_TRANSFER);
 
+	device_claim_softc(dev);
+
+	uvisor_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(uvisor);
 
 static void
-uvisor_free_softc(device_t dev, void *arg)
+uvisor_free_softc(struct uvisor_softc *sc)
 {
-	struct uvisor_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 uvisor_free(struct ucom_softc *ucom)
 {
-	uvisor_free_softc(NULL, ucom->sc_parent);
+	uvisor_free_softc(ucom->sc_parent);
 }
 
 static usb_error_t
diff --git a/sys/dev/usb/serial/uvscom.c b/sys/dev/usb/serial/uvscom.c
index bb91c40..b4aa370 100644
--- a/sys/dev/usb/serial/uvscom.c
+++ b/sys/dev/usb/serial/uvscom.c
@@ -163,7 +163,7 @@ struct uvscom_softc {
 static device_probe_t uvscom_probe;
 static device_attach_t uvscom_attach;
 static device_detach_t uvscom_detach;
-static device_free_softc_t uvscom_free_softc;
+static void uvscom_free_softc(struct uvscom_softc *);
 
 static usb_callback_t uvscom_write_callback;
 static usb_callback_t uvscom_read_callback;
@@ -253,7 +253,6 @@ static device_method_t uvscom_methods[] = {
 	DEVMETHOD(device_probe, uvscom_probe),
 	DEVMETHOD(device_attach, uvscom_attach),
 	DEVMETHOD(device_detach, uvscom_detach),
-	DEVMETHOD(device_free_softc, uvscom_free_softc),
 	DEVMETHOD_END
 };
 
@@ -354,27 +353,28 @@ uvscom_detach(device_t dev)
 	ucom_detach(&sc->sc_super_ucom, &sc->sc_ucom);
 	usbd_transfer_unsetup(sc->sc_xfer, UVSCOM_N_TRANSFER);
 
+	device_claim_softc(dev);
+
+	uvscom_free_softc(sc);
+
 	return (0);
 }
 
 UCOM_UNLOAD_DRAIN(uvscom);
 
 static void
-uvscom_free_softc(device_t dev, void *arg)
+uvscom_free_softc(struct uvscom_softc *sc)
 {
-	struct uvscom_softc *sc = arg;
-
 	if (ucom_unref(&sc->sc_super_ucom)) {
-		if (mtx_initialized(&sc->sc_mtx))
-			mtx_destroy(&sc->sc_mtx);
-		device_free_softc(dev, sc);
+		mtx_destroy(&sc->sc_mtx);
+		device_free_softc(sc);
 	}
 }
 
 static void
 uvscom_free(struct ucom_softc *ucom)
 {
-	uvscom_free_softc(NULL, ucom->sc_parent);
+	uvscom_free_softc(ucom->sc_parent);
 }
 
 static void
diff --git a/sys/kern/device_if.m b/sys/kern/device_if.m
index edec42b..eb720eb 100644
--- a/sys/kern/device_if.m
+++ b/sys/kern/device_if.m
@@ -316,14 +316,3 @@ METHOD int resume {
 METHOD int quiesce {
 	device_t dev;
 } DEFAULT null_quiesce;
-
-/**
- * @brief Free the device softc
- *
- * @param _dev		device pointer
- * @param _softc	pointer to softc
- */
-METHOD void free_softc {
-	device_t	_dev;
-	void		*_softc;
-} DEFAULT device_free_softc;
diff --git a/sys/kern/subr_bus.c b/sys/kern/subr_bus.c
index 1356684..fa19cfd 100644
--- a/sys/kern/subr_bus.c
+++ b/sys/kern/subr_bus.c
@@ -2406,8 +2406,8 @@ device_get_softc(device_t dev)
 void
 device_set_softc(device_t dev, void *softc)
 {
-	if (dev->softc != NULL && !(dev->flags & DF_EXTERNALSOFTC))
-		DEVICE_FREE_SOFTC(dev, dev->softc);
+	if (dev->softc && !(dev->flags & DF_EXTERNALSOFTC))
+		free(dev->softc, M_BUS_SC);
 	dev->softc = softc;
 	if (dev->softc)
 		dev->flags |= DF_EXTERNALSOFTC;
@@ -2416,6 +2416,35 @@ device_set_softc(device_t dev, void *softc)
 }
 
 /**
+ * @brief Free claimed softc
+ *
+ * Most drivers do not need to use this since the softc is freed
+ * automatically when the driver is detached.
+ */
+void
+device_free_softc(void *softc)
+{
+	free(softc, M_BUS_SC);
+}
+
+/**
+ * @brief Claim softc
+ *
+ * This function can be used to let the driver free the automatically
+ * allocated softc using "device_free_softc()". This function is
+ * useful when the driver is refcounting the softc and the softc
+ * cannot be freed when the "device_detach" method is called.
+ */
+void
+device_claim_softc(device_t dev)
+{
+	if (dev->softc)
+		dev->flags |= DF_EXTERNALSOFTC;
+	else
+		dev->flags &= ~DF_EXTERNALSOFTC;
+}
+
+/**
  * @brief Get the device's ivars field
  *
  * The ivars field is used by the parent device to store per-device
@@ -2604,8 +2633,8 @@ device_set_driver(device_t dev, driver_t *driver)
 	if (dev->driver == driver)
 		return (0);
 
-	if (dev->softc != NULL && !(dev->flags & DF_EXTERNALSOFTC)) {
-		DEVICE_FREE_SOFTC(dev, dev->softc);
+	if (dev->softc && !(dev->flags & DF_EXTERNALSOFTC)) {
+		free(dev->softc, M_BUS_SC);
 		dev->softc = NULL;
 	}
 	device_set_desc(dev, NULL);
@@ -4797,13 +4826,3 @@ bus_free_resource(device_t dev, int type, struct resource *r)
 		return (0);
 	return (bus_release_resource(dev, type, rman_get_rid(r), r));
 }
-
-/*
- * The "dev" argument passed to "device_free_softc()" is allowed to be
- * NULL, if the device freeing the soft is not available.
- */
-void
-device_free_softc(device_t dev, void *softc)
-{
-	free(softc, M_BUS_SC);
-}
diff --git a/sys/sys/bus.h b/sys/sys/bus.h
index 941819a..db6d3cf 100644
--- a/sys/sys/bus.h
+++ b/sys/sys/bus.h
@@ -464,11 +464,12 @@ int	device_set_devclass(device_t dev, const char *classname);
 int	device_set_driver(device_t dev, driver_t *driver);
 void	device_set_flags(device_t dev, u_int32_t flags);
 void	device_set_softc(device_t dev, void *softc);
+void	device_free_softc(void *softc);
+void	device_claim_softc(device_t dev);
 int	device_set_unit(device_t dev, int unit);	/* XXX DONT USE XXX */
 int	device_shutdown(device_t dev);
 void	device_unbusy(device_t dev);
 void	device_verbose(device_t dev);
-void	device_free_softc(device_t dev, void *softc);
 
 /*
  * Access functions for devclass.