[PATCH] isdn4linux: Siemens Gigaset base driver: fix disconnect handling

Fix a possible Oops in the Siemens Gigaset base driver when the device is
unplugged while an ISDN connection is still active, and makes sure that the
isdn4linux link level (LL) is properly informed if a connection is broken
by the USB cable being unplugged.

- Avoid unsafe checks of URB status fields outside the URB completion
  handlers, keep track of in-use URBs myself instead.

- If an isochronous transfer URB completes with status==0, also check the
  status of the frame descriptors.

- Verify length of interrupt messages received from the device.

- Align the length limit on transmitted AT commands with the device
  documentation.

- In case of AT response receive overrun, keep newly arrived instead of old
  unread data.

- Remove redundant check of device ID in the USB probe function.

- Correct and improve some comments and formatting.

Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Acked-by: Hansjoerg Lipp <hjlipp@web.de>
Cc: Karsten Keil <kkeil@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

6 files changed, 342 insertions, 280 deletions

diff --git a/drivers/isdn/gigaset/bas-gigaset.c b/drivers/isdn/gigaset/bas-gigaset.c
index f86ed6af3aa2..eb41aba3ddef 100644
--- a/drivers/isdn/gigaset/bas-gigaset.c
+++ b/drivers/isdn/gigaset/bas-gigaset.c
@@ -5,8 +5,6 @@
  *                       Tilman Schmidt <tilman@imap.cc>,
  *                       Stefan Eilers.
  *
- * Based on usb-gigaset.c.
- *
  * =====================================================================
  *	This program is free software; you can redistribute it and/or
  *	modify it under the terms of the GNU General Public License as
@@ -46,19 +44,20 @@ MODULE_PARM_DESC(cidmode, "Call-ID mode");
 #define GIGASET_DEVFSNAME  "gig/bas/"
 #define GIGASET_DEVNAME    "ttyGB"
 
-#define IF_WRITEBUF 256 //FIXME
+/* length limit according to Siemens 3070usb-protokoll.doc ch. 2.1 */
+#define IF_WRITEBUF 264
 
 /* Values for the Gigaset 307x */
 #define USB_GIGA_VENDOR_ID      0x0681
-#define USB_GIGA_PRODUCT_ID     0x0001
-#define USB_4175_PRODUCT_ID     0x0002
+#define USB_3070_PRODUCT_ID     0x0001
+#define USB_3075_PRODUCT_ID     0x0002
 #define USB_SX303_PRODUCT_ID    0x0021
 #define USB_SX353_PRODUCT_ID    0x0022
 
 /* table of devices that work with this driver */
 static struct usb_device_id gigaset_table [] = {
-	{ USB_DEVICE(USB_GIGA_VENDOR_ID, USB_GIGA_PRODUCT_ID) },
-	{ USB_DEVICE(USB_GIGA_VENDOR_ID, USB_4175_PRODUCT_ID) },
+	{ USB_DEVICE(USB_GIGA_VENDOR_ID, USB_3070_PRODUCT_ID) },
+	{ USB_DEVICE(USB_GIGA_VENDOR_ID, USB_3075_PRODUCT_ID) },
 	{ USB_DEVICE(USB_GIGA_VENDOR_ID, USB_SX303_PRODUCT_ID) },
 	{ USB_DEVICE(USB_GIGA_VENDOR_ID, USB_SX353_PRODUCT_ID) },
 	{ } /* Terminating entry */
@@ -77,6 +76,10 @@ static int gigaset_probe(struct usb_interface *interface,
 /* Function will be called if the device is unplugged */
 static void gigaset_disconnect(struct usb_interface *interface);
 
+static void read_ctrl_callback(struct urb *, struct pt_regs *);
+static void stopurbs(struct bas_bc_state *);
+static int atwrite_submit(struct cardstate *, unsigned char *, int);
+static int start_cbsend(struct cardstate *);
 
 /*==============================================================================*/
 
@@ -111,12 +114,14 @@ struct bas_cardstate {
 };
 
 /* status of direct USB connection to 307x base (bits in basstate) */
-#define BS_ATOPEN	0x001
-#define BS_B1OPEN	0x002
-#define BS_B2OPEN	0x004
-#define BS_ATREADY	0x008
-#define BS_INIT		0x010
-#define BS_ATTIMER	0x020
+#define BS_ATOPEN	0x001	/* AT channel open */
+#define BS_B1OPEN	0x002	/* B channel 1 open */
+#define BS_B2OPEN	0x004	/* B channel 2 open */
+#define BS_ATREADY	0x008	/* base ready for AT command */
+#define BS_INIT		0x010	/* base has signalled INIT_OK */
+#define BS_ATTIMER	0x020	/* waiting for HD_READY_SEND_ATDATA */
+#define BS_ATRDPEND	0x040	/* urb_cmd_in in use */
+#define BS_ATWRPEND	0x080	/* urb_cmd_out in use */
 
 
 static struct gigaset_driver *driver = NULL;
@@ -130,6 +135,47 @@ static struct usb_driver gigaset_usb_driver = {
 	.id_table =     gigaset_table,
 };
 
+/* get message text for usb_submit_urb return code
+ */
+static char *get_usb_rcmsg(int rc)
+{
+	static char unkmsg[28];
+
+	switch (rc) {
+	case 0:
+		return "success";
+	case -ENOMEM:
+		return "out of memory";
+	case -ENODEV:
+		return "device not present";
+	case -ENOENT:
+		return "endpoint not present";
+	case -ENXIO:
+		return "URB type not supported";
+	case -EINVAL:
+		return "invalid argument";
+	case -EAGAIN:
+		return "start frame too early or too much scheduled";
+	case -EFBIG:
+		return "too many isochronous frames requested";
+	case -EPIPE:
+		return "endpoint stalled";
+	case -EMSGSIZE:
+		return "invalid packet size";
+	case -ENOSPC:
+		return "would overcommit USB bandwidth";
+	case -ESHUTDOWN:
+		return "device shut down";
+	case -EPERM:
+		return "reject flag set";
+	case -EHOSTUNREACH:
+		return "device suspended";
+	default:
+		snprintf(unkmsg, sizeof(unkmsg), "unknown error %d", rc);
+		return unkmsg;
+	}
+}
+
 /* get message text for USB status code
  */
 static char *get_usb_statmsg(int status)
@@ -140,43 +186,37 @@ static char *get_usb_statmsg(int status)
 	case 0:
 		return "success";
 	case -ENOENT:
-		return "canceled";
-	case -ECONNRESET:
-		return "canceled (async)";
+		return "unlinked (sync)";
 	case -EINPROGRESS:
 		return "pending";
 	case -EPROTO:
-		return "bit stuffing or unknown USB error";
+		return "bit stuffing error, timeout, or unknown USB error";
 	case -EILSEQ:
-		return "Illegal byte sequence (CRC mismatch)";
-	case -EPIPE:
-		return "babble detect or endpoint stalled";
-	case -ENOSR:
-		return "buffer error";
+		return "CRC mismatch, timeout, or unknown USB error";
 	case -ETIMEDOUT:
 		return "timed out";
-	case -ENODEV:
-		return "device not present";
+	case -EPIPE:
+		return "endpoint stalled";
+	case -ECOMM:
+		return "IN buffer overrun";
+	case -ENOSR:
+		return "OUT buffer underrun";
+	case -EOVERFLOW:
+		return "too much data";
 	case -EREMOTEIO:
 		return "short packet detected";
+	case -ENODEV:
+		return "device removed";
 	case -EXDEV:
 		return "partial isochronous transfer";
 	case -EINVAL:
 		return "invalid argument";
-	case -ENXIO:
-		return "URB already queued";
-	case -EAGAIN:
-		return "isochronous start frame too early or too much scheduled";
-	case -EFBIG:
-		return "too many isochronous frames requested";
-	case -EMSGSIZE:
-		return "endpoint message size zero";
+	case -ECONNRESET:
+		return "unlinked (async)";
 	case -ESHUTDOWN:
-		return "endpoint shutdown";
-	case -EBUSY:
-		return "another request pending";
+		return "device shut down";
 	default:
-		snprintf(unkmsg, sizeof(unkmsg), "unknown error %d", status);
+		snprintf(unkmsg, sizeof(unkmsg), "unknown status %d", status);
 		return unkmsg;
 	}
 }
@@ -277,18 +317,17 @@ static inline void error_hangup(struct bc_state *bcs)
 	gig_dbg(DEBUG_ANY, "%s: scheduling HUP for channel %d",
 		__func__, bcs->channel);
 
-	if (!gigaset_add_event(cs, &bcs->at_state, EV_HUP, NULL, 0, NULL)) {
-		//FIXME what should we do?
-		return;
-	}
+	if (!gigaset_add_event(cs, &bcs->at_state, EV_HUP, NULL, 0, NULL))
+		dev_err(cs->dev, "event queue full\n");
 
 	gigaset_schedule_event(cs);
 }
 
 /* error_reset
  * reset Gigaset device because of an unrecoverable error
- * This function may be called from any context and takes care of scheduling
- * the necessary actions for execution outside of interrupt context.
+ * This function may be called from any context, and should take care of
+ * scheduling the necessary actions for execution outside of interrupt context.
+ * Right now, it just generates a kernel message calling for help.
  * argument:
  *	controller state structure
  */
@@ -364,36 +403,38 @@ static void cmd_in_timeout(unsigned long data)
 {
 	struct cardstate *cs = (struct cardstate *) data;
 	struct bas_cardstate *ucs = cs->hw.bas;
-	unsigned long flags;
 
-	spin_lock_irqsave(&cs->lock, flags);
-	if (unlikely(!cs->connected)) {
-		gig_dbg(DEBUG_USBREQ, "%s: disconnected", __func__);
-		spin_unlock_irqrestore(&cs->lock, flags);
-		return;
-	}
 	if (!ucs->rcvbuf_size) {
 		gig_dbg(DEBUG_USBREQ, "%s: no receive in progress", __func__);
-		spin_unlock_irqrestore(&cs->lock, flags);
 		return;
 	}
-	spin_unlock_irqrestore(&cs->lock, flags);
 
 	dev_err(cs->dev, "timeout reading AT response\n");
 	error_reset(cs);	//FIXME retry?
 }
 
+/* set/clear bits in base connection state, return previous state
+ */
+inline static int update_basstate(struct bas_cardstate *ucs,
+				  int set, int clear)
+{
+	unsigned long flags;
+	int state;
 
-static void read_ctrl_callback(struct urb *urb, struct pt_regs *regs);
+	spin_lock_irqsave(&ucs->lock, flags);
+	state = atomic_read(&ucs->basstate);
+	atomic_set(&ucs->basstate, (state & ~clear) | set);
+	spin_unlock_irqrestore(&ucs->lock, flags);
+	return state;
+}
 
 /* atread_submit
- * submit an HD_READ_ATMESSAGE command URB
+ * submit an HD_READ_ATMESSAGE command URB and optionally start a timeout
  * parameters:
  *	cs	controller state structure
  *	timeout	timeout in 1/10 sec., 0: none
  * return value:
  *	0 on success
- *	-EINVAL if a NULL pointer is encountered somewhere
  *	-EBUSY if another request is pending
  *	any URB submission error code
  */
@@ -405,7 +446,7 @@ static int atread_submit(struct cardstate *cs, int timeout)
 	gig_dbg(DEBUG_USBREQ, "-------> HD_READ_ATMESSAGE (%d)",
 		ucs->rcvbuf_size);
 
-	if (ucs->urb_cmd_in->status == -EINPROGRESS) {
+	if (update_basstate(ucs, BS_ATRDPEND, 0) & BS_ATRDPEND) {
 		dev_err(cs->dev,
 			"could not submit HD_READ_ATMESSAGE: URB busy\n");
 		return -EBUSY;
@@ -423,6 +464,7 @@ static int atread_submit(struct cardstate *cs, int timeout)
 			     read_ctrl_callback, cs->inbuf);
 
 	if ((ret = usb_submit_urb(ucs->urb_cmd_in, SLAB_ATOMIC)) != 0) {
+		update_basstate(ucs, 0, BS_ATRDPEND);
 		dev_err(cs->dev, "could not submit HD_READ_ATMESSAGE: %s\n",
 			get_usb_statmsg(ret));
 		return ret;
@@ -438,26 +480,6 @@ static int atread_submit(struct cardstate *cs, int timeout)
 	return 0;
 }
 
-static void stopurbs(struct bas_bc_state *);
-static int start_cbsend(struct cardstate *);
-
-/* set/clear bits in base connection state
- */
-inline static void update_basstate(struct bas_cardstate *ucs,
-				   int set, int clear)
-{
-	unsigned long flags;
-	int state;
-
-	spin_lock_irqsave(&ucs->lock, flags);
-	state = atomic_read(&ucs->basstate);
-	state &= ~clear;
-	state |= set;
-	atomic_set(&ucs->basstate, state);
-	spin_unlock_irqrestore(&ucs->lock, flags);
-}
-
-
 /* read_int_callback
  * USB completion handler for interrupt pipe input
  * called by the USB subsystem in interrupt context
@@ -471,20 +493,25 @@ static void read_int_callback(struct urb *urb, struct pt_regs *regs)
 	struct bas_cardstate *ucs = cs->hw.bas;
 	struct bc_state *bcs;
 	unsigned long flags;
-	int status;
+	int rc;
 	unsigned l;
 	int channel;
 
 	switch (urb->status) {
 	case 0:			/* success */
 		break;
-	case -ENOENT:			/* canceled */
-	case -ECONNRESET:		/* canceled (async) */
+	case -ENOENT:			/* cancelled */
+	case -ECONNRESET:		/* cancelled (async) */
 	case -EINPROGRESS:		/* pending */
 		/* ignore silently */
 		gig_dbg(DEBUG_USBREQ, "%s: %s",
 			__func__, get_usb_statmsg(urb->status));
 		return;
+	case -ENODEV:			/* device removed */
+	case -ESHUTDOWN:		/* device shut down */
+		//FIXME use this as disconnect indicator?
+		gig_dbg(DEBUG_USBREQ, "%s: device disconnected", __func__);
+		return;
 	default:		/* severe trouble */
 		dev_warn(cs->dev, "interrupt read: %s\n",
 			 get_usb_statmsg(urb->status));
@@ -492,6 +519,13 @@ static void read_int_callback(struct urb *urb, struct pt_regs *regs)
 		goto resubmit;
 	}
 
+	/* drop incomplete packets even if the missing bytes wouldn't matter */
+	if (unlikely(urb->actual_length < 3)) {
+		dev_warn(cs->dev, "incomplete interrupt packet (%d bytes)\n",
+			 urb->actual_length);
+		goto resubmit;
+	}
+
 	l = (unsigned) ucs->int_in_buf[1] +
 	    (((unsigned) ucs->int_in_buf[2]) << 8);
 
@@ -558,25 +592,28 @@ static void read_int_callback(struct urb *urb, struct pt_regs *regs)
 		}
 		spin_lock_irqsave(&cs->lock, flags);
 		if (ucs->rcvbuf_size) {
-			spin_unlock_irqrestore(&cs->lock, flags);
+			/* throw away previous buffer - we have no queue */
 			dev_err(cs->dev,
-				"receive AT data overrun, %d bytes lost\n", l);
-			error_reset(cs);	//FIXME reschedule
-			break;
+				"receive AT data overrun, %d bytes lost\n",
+				ucs->rcvbuf_size);
+			kfree(ucs->rcvbuf);
+			ucs->rcvbuf_size = 0;
 		}
 		if ((ucs->rcvbuf = kmalloc(l, GFP_ATOMIC)) == NULL) {
 			spin_unlock_irqrestore(&cs->lock, flags);
-			dev_err(cs->dev, "out of memory, %d bytes lost\n", l);
-			error_reset(cs);	//FIXME reschedule
+			dev_err(cs->dev, "out of memory receiving AT data\n");
+			error_reset(cs);
 			break;
 		}
 		ucs->rcvbuf_size = l;
 		ucs->retry_cmd_in = 0;
-		if ((status = atread_submit(cs, BAS_TIMEOUT)) < 0) {
+		if ((rc = atread_submit(cs, BAS_TIMEOUT)) < 0) {
 			kfree(ucs->rcvbuf);
 			ucs->rcvbuf = NULL;
 			ucs->rcvbuf_size = 0;
-			error_reset(cs);	//FIXME reschedule
+			if (rc != -ENODEV)
+				//FIXME corrective action?
+				error_reset(cs);
 		}
 		spin_unlock_irqrestore(&cs->lock, flags);
 		break;
@@ -598,12 +635,10 @@ static void read_int_callback(struct urb *urb, struct pt_regs *regs)
 	check_pending(ucs);
 
 resubmit:
-	spin_lock_irqsave(&cs->lock, flags);
-	status = cs->connected ? usb_submit_urb(urb, SLAB_ATOMIC) : -ENODEV;
-	spin_unlock_irqrestore(&cs->lock, flags);
-	if (unlikely(status)) {
+	rc = usb_submit_urb(urb, SLAB_ATOMIC);
+	if (unlikely(rc != 0 && rc != -ENODEV)) {
 		dev_err(cs->dev, "could not resubmit interrupt URB: %s\n",
-			get_usb_statmsg(status));
+			get_usb_rcmsg(rc));
 		error_reset(cs);
 	}
 }
@@ -622,18 +657,12 @@ static void read_ctrl_callback(struct urb *urb, struct pt_regs *regs)
 	struct bas_cardstate *ucs = cs->hw.bas;
 	int have_data = 0;
 	unsigned numbytes;
-	unsigned long flags;
+	int rc;
 
-	spin_lock_irqsave(&cs->lock, flags);
-	if (unlikely(!cs->connected)) {
-		warn("%s: disconnected", __func__);
-		spin_unlock_irqrestore(&cs->lock, flags);
-		return;
-	}
+	update_basstate(ucs, 0, BS_ATRDPEND);
 
 	if (!ucs->rcvbuf_size) {
 		dev_warn(cs->dev, "%s: no receive in progress\n", __func__);
-		spin_unlock_irqrestore(&cs->lock, flags);
 		return;
 	}
 
@@ -666,9 +695,11 @@ static void read_ctrl_callback(struct urb *urb, struct pt_regs *regs)
 		}
 		break;
 
-	case -ENOENT:			/* canceled */
-	case -ECONNRESET:		/* canceled (async) */
+	case -ENOENT:			/* cancelled */
+	case -ECONNRESET:		/* cancelled (async) */
 	case -EINPROGRESS:		/* pending */
+	case -ENODEV:			/* device removed */
+	case -ESHUTDOWN:		/* device shut down */
 		/* no action necessary */
 		gig_dbg(DEBUG_USBREQ, "%s: %s",
 			__func__, get_usb_statmsg(urb->status));
@@ -681,11 +712,11 @@ static void read_ctrl_callback(struct urb *urb, struct pt_regs *regs)
 		if (ucs->retry_cmd_in++ < BAS_RETRY) {
 			dev_notice(cs->dev, "control read: retry %d\n",
 				   ucs->retry_cmd_in);
-			if (atread_submit(cs, BAS_TIMEOUT) >= 0) {
-				/* resubmitted - bypass regular exit block */
-				spin_unlock_irqrestore(&cs->lock, flags);
+			rc = atread_submit(cs, BAS_TIMEOUT);
+			if (rc >= 0 || rc == -ENODEV)
+				/* resubmitted or disconnected */
+				/* - bypass regular exit block */
 				return;
-			}
 		} else {
 			dev_err(cs->dev,
 				"control read: giving up after %d tries\n",
@@ -697,7 +728,6 @@ static void read_ctrl_callback(struct urb *urb, struct pt_regs *regs)
 	kfree(ucs->rcvbuf);
 	ucs->rcvbuf = NULL;
 	ucs->rcvbuf_size = 0;
-	spin_unlock_irqrestore(&cs->lock, flags);
 	if (have_data) {
 		gig_dbg(DEBUG_INTR, "%s-->BH", __func__);
 		gigaset_schedule_event(cs);
@@ -719,8 +749,11 @@ static void read_iso_callback(struct urb *urb, struct pt_regs *regs)
 	int i, rc;
 
 	/* status codes not worth bothering the tasklet with */
-	if (unlikely(urb->status == -ENOENT || urb->status == -ECONNRESET ||
-		     urb->status == -EINPROGRESS)) {
+	if (unlikely(urb->status == -ENOENT ||
+		     urb->status == -ECONNRESET ||
+		     urb->status == -EINPROGRESS ||
+		     urb->status == -ENODEV ||
+		     urb->status == -ESHUTDOWN)) {
 		gig_dbg(DEBUG_ISO, "%s: %s",
 			__func__, get_usb_statmsg(urb->status));
 		return;
@@ -740,9 +773,9 @@ static void read_iso_callback(struct urb *urb, struct pt_regs *regs)
 		for (i = 0; i < BAS_NUMFRAMES; i++) {
 			ubc->isoinlost += urb->iso_frame_desc[i].actual_length;
 			if (unlikely(urb->iso_frame_desc[i].status != 0 &&
-				     urb->iso_frame_desc[i].status != -EINPROGRESS)) {
+				     urb->iso_frame_desc[i].status !=
+								-EINPROGRESS))
 				ubc->loststatus = urb->iso_frame_desc[i].status;
-			}
 			urb->iso_frame_desc[i].status = 0;
 			urb->iso_frame_desc[i].actual_length = 0;
 		}
@@ -754,10 +787,10 @@ static void read_iso_callback(struct urb *urb, struct pt_regs *regs)
 			gig_dbg(DEBUG_ISO, "%s: isoc read overrun/resubmit",
 				__func__);
 			rc = usb_submit_urb(urb, SLAB_ATOMIC);
-			if (unlikely(rc != 0)) {
+			if (unlikely(rc != 0 && rc != -ENODEV)) {
 				dev_err(bcs->cs->dev,
 					"could not resubmit isochronous read "
-					"URB: %s\n", get_usb_statmsg(rc));
+					"URB: %s\n", get_usb_rcmsg(rc));
 				dump_urb(DEBUG_ISO, "isoc read", urb);
 				error_hangup(bcs);
 			}
@@ -780,8 +813,11 @@ static void write_iso_callback(struct urb *urb, struct pt_regs *regs)
 	unsigned long flags;
 
 	/* status codes not worth bothering the tasklet with */
-	if (unlikely(urb->status == -ENOENT || urb->status == -ECONNRESET ||
-		     urb->status == -EINPROGRESS)) {
+	if (unlikely(urb->status == -ENOENT ||
+		     urb->status == -ECONNRESET ||
+		     urb->status == -EINPROGRESS ||
+		     urb->status == -ENODEV ||
+		     urb->status == -ESHUTDOWN)) {
 		gig_dbg(DEBUG_ISO, "%s: %s",
 			__func__, get_usb_statmsg(urb->status));
 		return;
@@ -822,7 +858,6 @@ static int starturbs(struct bc_state *bcs)
 	for (k = 0; k < BAS_INURBS; k++) {
 		urb = ubc->isoinurbs[k];
 		if (!urb) {
-			dev_err(bcs->cs->dev, "isoinurbs[%d]==NULL\n", k);
 			rc = -EFAULT;
 			goto error;
 		}
@@ -844,12 +879,8 @@ static int starturbs(struct bc_state *bcs)
 		}
 
 		dump_urb(DEBUG_ISO, "Initial isoc read", urb);
-		if ((rc = usb_submit_urb(urb, SLAB_ATOMIC)) != 0) {
-			dev_err(bcs->cs->dev,
-			       "could not submit isochronous read URB %d: %s\n",
-				k, get_usb_statmsg(rc));
+		if ((rc = usb_submit_urb(urb, SLAB_ATOMIC)) != 0)
 			goto error;
-		}
 	}
 
 	/* initialize L2 transmission */
@@ -859,7 +890,6 @@ static int starturbs(struct bc_state *bcs)
 	for (k = 0; k < BAS_OUTURBS; ++k) {
 		urb = ubc->isoouturbs[k].urb;
 		if (!urb) {
-			dev_err(bcs->cs->dev, "isoouturbs[%d].urb==NULL\n", k);
 			rc = -EFAULT;
 			goto error;
 		}
@@ -885,12 +915,8 @@ static int starturbs(struct bc_state *bcs)
 	for (k = 0; k < 2; ++k) {
 		dump_urb(DEBUG_ISO, "Initial isoc write", urb);
 		rc = usb_submit_urb(ubc->isoouturbs[k].urb, SLAB_ATOMIC);
-		if (rc != 0) {
-			dev_err(bcs->cs->dev,
-			      "could not submit isochronous write URB %d: %s\n",
-				k, get_usb_statmsg(rc));
+		if (rc != 0)
 			goto error;
-		}
 	}
 	dump_urb(DEBUG_ISO, "Initial isoc write (free)", urb);
 	ubc->isooutfree = &ubc->isoouturbs[2];
@@ -916,15 +942,15 @@ static void stopurbs(struct bas_bc_state *ubc)
 	for (k = 0; k < BAS_INURBS; ++k) {
 		rc = usb_unlink_urb(ubc->isoinurbs[k]);
 		gig_dbg(DEBUG_ISO,
-			"%s: isoc input URB %d unlinked, result = %d",
-			__func__, k, rc);
+			"%s: isoc input URB %d unlinked, result = %s",
+			__func__, k, get_usb_rcmsg(rc));
 	}
 
 	for (k = 0; k < BAS_OUTURBS; ++k) {
 		rc = usb_unlink_urb(ubc->isoouturbs[k].urb);
 		gig_dbg(DEBUG_ISO,
-			"%s: isoc output URB %d unlinked, result = %d",
-			__func__, k, rc);
+			"%s: isoc output URB %d unlinked, result = %s",
+			__func__, k, get_usb_rcmsg(rc));
 	}
 }
 
@@ -934,7 +960,7 @@ static void stopurbs(struct bas_bc_state *ubc)
 /* submit_iso_write_urb
  * fill and submit the next isochronous write URB
  * parameters:
- *	bcs	B channel state structure
+ *	ucx	context structure containing URB
  * return value:
  *	number of frames submitted in URB
  *	0 if URB not submitted because no data available (isooutbuf busy)
@@ -946,7 +972,6 @@ static int submit_iso_write_urb(struct isow_urbctx_t *ucx)
 	struct bas_bc_state *ubc = ucx->bcs->hw.bas;
 	struct usb_iso_packet_descriptor *ifd;
 	int corrbytes, nframe, rc;
-	unsigned long flags;
 
 	/* urb->dev is clobbered by USB subsystem */
 	urb->dev = ucx->bcs->cs->hw.bas->udev;
@@ -992,20 +1017,22 @@ static int submit_iso_write_urb(struct isow_urbctx_t *ucx)
 		ifd->status = 0;
 		ifd->actual_length = 0;
 	}
-	if ((urb->number_of_packets = nframe) > 0) {
-		spin_lock_irqsave(&ucx->bcs->cs->lock, flags);
-		rc = ucx->bcs->cs->connected ? usb_submit_urb(urb, SLAB_ATOMIC) : -ENODEV;
-		spin_unlock_irqrestore(&ucx->bcs->cs->lock, flags);
+	if (unlikely(nframe == 0))
+		return 0;	/* no data to send */
+	urb->number_of_packets = nframe;
 
-		if (rc) {
+	rc = usb_submit_urb(urb, SLAB_ATOMIC);
+	if (unlikely(rc)) {
+		if (rc == -ENODEV)
+			/* device removed - give up silently */
+			gig_dbg(DEBUG_ISO, "%s: disconnected", __func__);
+		else
 			dev_err(ucx->bcs->cs->dev,
 				"could not submit isochronous write URB: %s\n",
-				get_usb_statmsg(rc));
-			dump_urb(DEBUG_ISO, "isoc write", urb);
-			return rc;
-		}
-		++ubc->numsub;
+				get_usb_rcmsg(rc));
+		return rc;
 	}
+	++ubc->numsub;
 	return nframe;
 }
 
@@ -1028,6 +1055,7 @@ static void write_iso_tasklet(unsigned long data)
 	int i;
 	struct sk_buff *skb;
 	int len;
+	int rc;
 
 	/* loop while completed URBs arrive in time */
 	for (;;) {
@@ -1057,7 +1085,8 @@ static void write_iso_tasklet(unsigned long data)
 		ubc->isooutfree = NULL;
 		spin_unlock_irqrestore(&ubc->isooutlock, flags);
 		if (next) {
-			if (submit_iso_write_urb(next) <= 0) {
+			rc = submit_iso_write_urb(next);
+			if (unlikely(rc <= 0 && rc != -ENODEV)) {
 				/* could not submit URB, put it back */
 				spin_lock_irqsave(&ubc->isooutlock, flags);
 				if (ubc->isooutfree == NULL) {
@@ -1077,17 +1106,18 @@ static void write_iso_tasklet(unsigned long data)
 		/* process completed URB */
 		urb = done->urb;
 		switch (urb->status) {
+		case -EXDEV:			/* partial completion */
+			gig_dbg(DEBUG_ISO, "%s: URB partially completed",
+				__func__);
+			/* fall through - what's the difference anyway? */
 		case 0:				/* normal completion */
-			break;
-		case -EXDEV:			/* inspect individual frames */
-			/* assumptions (for lack of documentation):
-			 * - actual_length bytes of the frame in error are
+			/* inspect individual frames
+			 * assumptions (for lack of documentation):
+			 * - actual_length bytes of first frame in error are
 			 *   successfully sent
 			 * - all following frames are not sent at all
 			 */
-			gig_dbg(DEBUG_ISO, "%s: URB partially completed",
-				__func__);
-			offset = done->limit;	/* just in case */
+			offset = done->limit;	/* default (no error) */
 			for (i = 0; i < BAS_NUMFRAMES; i++) {
 				ifd = &urb->iso_frame_desc[i];
 				if (ifd->status ||
@@ -1122,7 +1152,7 @@ static void write_iso_tasklet(unsigned long data)
 			}
 #endif
 			break;
-		case -EPIPE:		//FIXME is this the code for "underrun"?
+		case -EPIPE:			/* stall - probably underrun */
 			dev_err(cs->dev, "isochronous write stalled\n");
 			error_hangup(bcs);
 			break;
@@ -1142,7 +1172,8 @@ static void write_iso_tasklet(unsigned long data)
 		spin_unlock_irqrestore(&ubc->isooutlock, flags);
 		if (next) {
 			/* only one URB still active - resubmit one */
-			if (submit_iso_write_urb(next) <= 0) {
+			rc = submit_iso_write_urb(next);
+			if (unlikely(rc <= 0 && rc != -ENODEV)) {
 				/* couldn't submit */
 				error_hangup(bcs);
 			}
@@ -1222,10 +1253,9 @@ static void read_iso_tasklet(unsigned long data)
 			break;
 		case -ENOENT:
 		case -ECONNRESET:
-			gig_dbg(DEBUG_ISO, "%s: URB canceled", __func__);
-			continue;		/* -> skip */
-		case -EINPROGRESS:		/* huh? */
-			gig_dbg(DEBUG_ISO, "%s: URB still pending", __func__);
+		case -EINPROGRESS:
+			gig_dbg(DEBUG_ISO, "%s: %s",
+				__func__, get_usb_statmsg(urb->status));
 			continue;		/* -> skip */
 		case -EPIPE:
 			dev_err(cs->dev, "isochronous read stalled\n");
@@ -1290,13 +1320,11 @@ static void read_iso_tasklet(unsigned long data)
 		urb->dev = bcs->cs->hw.bas->udev;
 		urb->transfer_flags = URB_ISO_ASAP;
 		urb->number_of_packets = BAS_NUMFRAMES;
-		spin_lock_irqsave(&cs->lock, flags);
-		rc = cs->connected ? usb_submit_urb(urb, SLAB_ATOMIC) : -ENODEV;
-		spin_unlock_irqrestore(&cs->lock, flags);
-		if (rc) {
+		rc = usb_submit_urb(urb, SLAB_ATOMIC);
+		if (unlikely(rc != 0 && rc != -ENODEV)) {
 			dev_err(cs->dev,
 				"could not resubmit isochronous read URB: %s\n",
-				get_usb_statmsg(rc));
+				get_usb_rcmsg(rc));
 			dump_urb(DEBUG_ISO, "resubmit iso read", urb);
 			error_hangup(bcs);
 		}
@@ -1397,7 +1425,6 @@ static void write_ctrl_callback(struct urb *urb, struct pt_regs *regs)
  *	timeout	timeout in seconds (0: no timeout)
  * return value:
  *	0 on success
- *	-EINVAL if a NULL pointer is encountered somewhere
  *	-EBUSY if another request is pending
  *	any URB submission error code
  */
@@ -1418,12 +1445,6 @@ static int req_submit(struct bc_state *bcs, int req, int val, int timeout)
 			req, ucs->pending);
 		return -EBUSY;
 	}
-	if (ucs->urb_ctrl->status == -EINPROGRESS) {
-		spin_unlock_irqrestore(&ucs->lock, flags);
-		dev_err(bcs->cs->dev,
-			"could not submit request 0x%02x: URB busy\n", req);
-		return -EBUSY;
-	}
 
 	ucs->dr_ctrl.bRequestType = OUT_VENDOR_REQ;
 	ucs->dr_ctrl.bRequest = req;
@@ -1465,22 +1486,36 @@ static int req_submit(struct bc_state *bcs, int req, int val, int timeout)
 static int gigaset_init_bchannel(struct bc_state *bcs)
 {
 	int req, ret;
+	unsigned long flags;
+
+	spin_lock_irqsave(&bcs->cs->lock, flags);
+	if (unlikely(!bcs->cs->connected)) {
+		gig_dbg(DEBUG_USBREQ, "%s: not connected", __func__);
+		spin_unlock_irqrestore(&bcs->cs->lock, flags);
+		return -ENODEV;
+	}
 
 	if ((ret = starturbs(bcs)) < 0) {
 		dev_err(bcs->cs->dev,
-			"could not start isochronous I/O for channel %d\n",
-			bcs->channel + 1);
-		error_hangup(bcs);
+			"could not start isochronous I/O for channel B%d: %s\n",
+			bcs->channel + 1,
+			ret == -EFAULT ? "null URB" : get_usb_rcmsg(ret));
+		if (ret != -ENODEV)
+			error_hangup(bcs);
+		spin_unlock_irqrestore(&bcs->cs->lock, flags);
 		return ret;
 	}
 
 	req = bcs->channel ? HD_OPEN_B2CHANNEL : HD_OPEN_B1CHANNEL;
 	if ((ret = req_submit(bcs, req, 0, BAS_TIMEOUT)) < 0) {
-		dev_err(bcs->cs->dev, "could not open channel %d: %s\n",
-			bcs->channel + 1, get_usb_statmsg(ret));
+		dev_err(bcs->cs->dev, "could not open channel B%d\n",
+			bcs->channel + 1);
 		stopurbs(bcs->hw.bas);
-		error_hangup(bcs);
+		if (ret != -ENODEV)
+			error_hangup(bcs);
 	}
+
+	spin_unlock_irqrestore(&bcs->cs->lock, flags);
 	return ret;
 }
 
@@ -1497,19 +1532,30 @@ static int gigaset_init_bchannel(struct bc_state *bcs)
 static int gigaset_close_bchannel(struct bc_state *bcs)
 {
 	int req, ret;
+	unsigned long flags;
+
+	spin_lock_irqsave(&bcs->cs->lock, flags);
+	if (unlikely(!bcs->cs->connected)) {
+		spin_unlock_irqrestore(&bcs->cs->lock, flags);
+		gig_dbg(DEBUG_USBREQ, "%s: not connected", __func__);
+		return -ENODEV;
+	}
 
 	if (!(atomic_read(&bcs->cs->hw.bas->basstate) &
 	      (bcs->channel ? BS_B2OPEN : BS_B1OPEN))) {
 		/* channel not running: just signal common.c */
+		spin_unlock_irqrestore(&bcs->cs->lock, flags);
 		gigaset_bchannel_down(bcs);
 		return 0;
 	}
 
+	/* channel running: tell device to close it */
 	req = bcs->channel ? HD_CLOSE_B2CHANNEL : HD_CLOSE_B1CHANNEL;
 	if ((ret = req_submit(bcs, req, 0, BAS_TIMEOUT)) < 0)
-		dev_err(bcs->cs->dev,
-			"could not submit HD_CLOSE_BxCHANNEL request: %s\n",
-			get_usb_statmsg(ret));
+		dev_err(bcs->cs->dev, "closing channel B%d failed\n",
+			bcs->channel + 1);
+
+	spin_unlock_irqrestore(&bcs->cs->lock, flags);
 	return ret;
 }
 
@@ -1545,8 +1591,6 @@ static void complete_cb(struct cardstate *cs)
 	kfree(cb);
 }
 
-static int atwrite_submit(struct cardstate *cs, unsigned char *buf, int len);
-
 /* write_command_callback
  * USB completion handler for AT command transmission
  * called by the USB subsystem in interrupt context
@@ -1560,13 +1604,17 @@ static void write_command_callback(struct urb *urb, struct pt_regs *regs)
 	struct bas_cardstate *ucs = cs->hw.bas;
 	unsigned long flags;
 
+	update_basstate(ucs, 0, BS_ATWRPEND);
+
 	/* check status */
 	switch (urb->status) {
 	case 0:					/* normal completion */
 		break;
-	case -ENOENT:			/* canceled */
-	case -ECONNRESET:		/* canceled (async) */
+	case -ENOENT:			/* cancelled */
+	case -ECONNRESET:		/* cancelled (async) */
 	case -EINPROGRESS:		/* pending */
+	case -ENODEV:			/* device removed */
+	case -ESHUTDOWN:		/* device shut down */
 		/* ignore silently */
 		gig_dbg(DEBUG_USBREQ, "%s: %s",
 			__func__, get_usb_statmsg(urb->status));
@@ -1627,19 +1675,17 @@ static void atrdy_timeout(unsigned long data)
  *	len	length of command to send
  * return value:
  *	0 on success
- *	-EFAULT if a NULL pointer is encountered somewhere
  *	-EBUSY if another request is pending
  *	any URB submission error code
  */
 static int atwrite_submit(struct cardstate *cs, unsigned char *buf, int len)
 {
 	struct bas_cardstate *ucs = cs->hw.bas;
-	unsigned long flags;
-	int ret;
+	int rc;
 
 	gig_dbg(DEBUG_USBREQ, "-------> HD_WRITE_ATMESSAGE (%d)", len);
 
-	if (ucs->urb_cmd_out->status == -EINPROGRESS) {
+	if (update_basstate(ucs, BS_ATWRPEND, 0) & BS_ATWRPEND) {
 		dev_err(cs->dev,
 			"could not submit HD_WRITE_ATMESSAGE: URB busy\n");
 		return -EBUSY;
@@ -1654,29 +1700,22 @@ static int atwrite_submit(struct cardstate *cs, unsigned char *buf, int len)
 			     usb_sndctrlpipe(ucs->udev, 0),
 			     (unsigned char*) &ucs->dr_cmd_out, buf, len,
 			     write_command_callback, cs);
-
-	spin_lock_irqsave(&cs->lock, flags);
-	ret = cs->connected ? usb_submit_urb(ucs->urb_cmd_out, SLAB_ATOMIC) : -ENODEV;
-	spin_unlock_irqrestore(&cs->lock, flags);
-
-	if (ret) {
+	rc = usb_submit_urb(ucs->urb_cmd_out, SLAB_ATOMIC);
+	if (unlikely(rc)) {
+		update_basstate(ucs, 0, BS_ATWRPEND);
 		dev_err(cs->dev, "could not submit HD_WRITE_ATMESSAGE: %s\n",
-			get_usb_statmsg(ret));
-		return ret;
+			get_usb_rcmsg(rc));
+		return rc;
 	}
 
-	/* submitted successfully */
-	update_basstate(ucs, 0, BS_ATREADY);
-
-	/* start timeout if necessary */
-	if (!(atomic_read(&ucs->basstate) & BS_ATTIMER)) {
+	/* submitted successfully, start timeout if necessary */
+	if (!(update_basstate(ucs, BS_ATTIMER, BS_ATREADY) & BS_ATTIMER)) {
 		gig_dbg(DEBUG_OUTPUT, "setting ATREADY timeout of %d/10 secs",
 			ATRDY_TIMEOUT);
 		ucs->timer_atrdy.expires = jiffies + ATRDY_TIMEOUT * HZ / 10;
 		ucs->timer_atrdy.data = (unsigned long) cs;
 		ucs->timer_atrdy.function = atrdy_timeout;
 		add_timer(&ucs->timer_atrdy);
-		update_basstate(ucs, BS_ATTIMER, 0);
 	}
 	return 0;
 }
@@ -1702,7 +1741,6 @@ static int start_cbsend(struct cardstate *cs)
 		gig_dbg(DEBUG_TRANSCMD|DEBUG_LOCKCMD, "AT channel not open");
 		rc = req_submit(cs->bcs, HD_OPEN_ATCHANNEL, 0, BAS_TIMEOUT);
 		if (rc < 0) {
-			dev_err(cs->dev, "could not open AT channel\n");
 			/* flush command queue */
 			spin_lock_irqsave(&cs->cmdlock, flags);
 			while (cs->cmdbuf != NULL)
@@ -1786,8 +1824,14 @@ static int gigaset_write_cmd(struct cardstate *cs,
 	cs->lastcmdbuf = cb;
 	spin_unlock_irqrestore(&cs->cmdlock, flags);
 
+	spin_lock_irqsave(&cs->lock, flags);
+	if (unlikely(!cs->connected)) {
+		spin_unlock_irqrestore(&cs->lock, flags);
+		gig_dbg(DEBUG_USBREQ, "%s: not connected", __func__);
+		return -ENODEV;
+	}
 	status = start_cbsend(cs);
-
+	spin_unlock_irqrestore(&cs->lock, flags);
 	return status < 0 ? status : len;
 }
 
@@ -1849,12 +1893,32 @@ static int gigaset_brkchars(struct cardstate *cs, const unsigned char buf[6])
  */
 static int gigaset_freebcshw(struct bc_state *bcs)
 {
-	if (!bcs->hw.bas)
+	struct bas_bc_state *ubc = bcs->hw.bas;
+	int i;
+
+	if (!ubc)
 		return 0;
 
-	if (bcs->hw.bas->isooutbuf)
-		kfree(bcs->hw.bas->isooutbuf);
-	kfree(bcs->hw.bas);
+	/* kill URBs and tasklets before freeing - better safe than sorry */
+	atomic_set(&ubc->running, 0);
+	for (i = 0; i < BAS_OUTURBS; ++i)
+		if (ubc->isoouturbs[i].urb) {
+			gig_dbg(DEBUG_INIT, "%s: killing iso out URB %d",
+				__func__, i);
+			usb_kill_urb(ubc->isoouturbs[i].urb);
+			usb_free_urb(ubc->isoouturbs[i].urb);
+		}
+	for (i = 0; i < BAS_INURBS; ++i)
+		if (ubc->isoinurbs[i]) {
+			gig_dbg(DEBUG_INIT, "%s: killing iso in URB %d",
+				__func__, i);
+			usb_kill_urb(ubc->isoinurbs[i]);
+			usb_free_urb(ubc->isoinurbs[i]);
+		}
+	tasklet_kill(&ubc->sent_tasklet);
+	tasklet_kill(&ubc->rcvd_tasklet);
+	kfree(ubc->isooutbuf);
+	kfree(ubc);
 	bcs->hw.bas = NULL;
 	return 1;
 }
@@ -1931,13 +1995,9 @@ static void gigaset_reinitbcshw(struct bc_state *bcs)
 
 static void gigaset_freecshw(struct cardstate *cs)
 {
-	struct bas_cardstate *ucs = cs->hw.bas;
-
-	del_timer(&ucs->timer_ctrl);
-	del_timer(&ucs->timer_atrdy);
-	del_timer(&ucs->timer_cmd_in);
-
+	/* timers, URBs and rcvbuf are disposed of in disconnect */
 	kfree(cs->hw.bas);
+	cs->hw.bas = NULL;
 }
 
 static int gigaset_initcshw(struct cardstate *cs)
@@ -2041,23 +2101,13 @@ static int gigaset_probe(struct usb_interface *interface,
 	struct bas_bc_state *ubc;
 	struct usb_endpoint_descriptor *endpoint;
 	int i, j;
-	int ret;
+	int rc;
 
 	gig_dbg(DEBUG_ANY,
 		"%s: Check if device matches .. (Vendor: 0x%x, Product: 0x%x)",
 		__func__, le16_to_cpu(udev->descriptor.idVendor),
 		le16_to_cpu(udev->descriptor.idProduct));
 
-	/* See if the device offered us matches what we can accept */
-	if ((le16_to_cpu(udev->descriptor.idVendor)  != USB_GIGA_VENDOR_ID) ||
-	    (le16_to_cpu(udev->descriptor.idProduct) != USB_GIGA_PRODUCT_ID &&
-	     le16_to_cpu(udev->descriptor.idProduct) != USB_4175_PRODUCT_ID &&
-	     le16_to_cpu(udev->descriptor.idProduct) != USB_SX303_PRODUCT_ID &&
-	     le16_to_cpu(udev->descriptor.idProduct) != USB_SX353_PRODUCT_ID)) {
-		gig_dbg(DEBUG_ANY, "%s: unmatched ID - exiting", __func__);
-		return -ENODEV;
-	}
-
 	/* set required alternate setting */
 	hostif = interface->cur_altsetting;
 	if (hostif->desc.bAlternateSetting != 3) {
@@ -2105,45 +2155,22 @@ static int gigaset_probe(struct usb_interface *interface,
 	 * - three for the different uses of the default control pipe
 	 * - three for each isochronous pipe
 	 */
-	ucs->urb_int_in = usb_alloc_urb(0, SLAB_KERNEL);
-	if (!ucs->urb_int_in) {
-		dev_err(cs->dev, "no free urbs available\n");
-		goto error;
-	}
-	ucs->urb_cmd_in = usb_alloc_urb(0, SLAB_KERNEL);
-	if (!ucs->urb_cmd_in) {
-		dev_err(cs->dev, "no free urbs available\n");
-		goto error;
-	}
-	ucs->urb_cmd_out = usb_alloc_urb(0, SLAB_KERNEL);
-	if (!ucs->urb_cmd_out) {
-		dev_err(cs->dev, "no free urbs available\n");
-		goto error;
-	}
-	ucs->urb_ctrl = usb_alloc_urb(0, SLAB_KERNEL);
-	if (!ucs->urb_ctrl) {
-		dev_err(cs->dev, "no free urbs available\n");
-		goto error;
-	}
+	if (!(ucs->urb_int_in = usb_alloc_urb(0, SLAB_KERNEL)) ||
+	    !(ucs->urb_cmd_in = usb_alloc_urb(0, SLAB_KERNEL)) ||
+	    !(ucs->urb_cmd_out = usb_alloc_urb(0, SLAB_KERNEL)) ||
+	    !(ucs->urb_ctrl = usb_alloc_urb(0, SLAB_KERNEL)))
+		goto allocerr;
 
 	for (j = 0; j < 2; ++j) {
 		ubc = cs->bcs[j].hw.bas;
-		for (i = 0; i < BAS_OUTURBS; ++i) {
-			ubc->isoouturbs[i].urb =
-				usb_alloc_urb(BAS_NUMFRAMES, SLAB_KERNEL);
-			if (!ubc->isoouturbs[i].urb) {
-				dev_err(cs->dev, "no free urbs available\n");
-				goto error;
-			}
-		}
-		for (i = 0; i < BAS_INURBS; ++i) {
-			ubc->isoinurbs[i] =
-				usb_alloc_urb(BAS_NUMFRAMES, SLAB_KERNEL);
-			if (!ubc->isoinurbs[i]) {
-				dev_err(cs->dev, "no free urbs available\n");
-				goto error;
-			}
-		}
+		for (i = 0; i < BAS_OUTURBS; ++i)
+			if (!(ubc->isoouturbs[i].urb =
+			      usb_alloc_urb(BAS_NUMFRAMES, SLAB_KERNEL)))
+				goto allocerr;
+		for (i = 0; i < BAS_INURBS; ++i)
+			if (!(ubc->isoinurbs[i] =
+			      usb_alloc_urb(BAS_NUMFRAMES, SLAB_KERNEL)))
+				goto allocerr;
 	}
 
 	ucs->rcvbuf = NULL;
@@ -2156,15 +2183,14 @@ static int gigaset_probe(struct usb_interface *interface,
 					(endpoint->bEndpointAddress) & 0x0f),
 			 ucs->int_in_buf, 3, read_int_callback, cs,
 			 endpoint->bInterval);
-	ret = usb_submit_urb(ucs->urb_int_in, SLAB_KERNEL);
-	if (ret) {
+	if ((rc = usb_submit_urb(ucs->urb_int_in, SLAB_KERNEL)) != 0) {
 		dev_err(cs->dev, "could not submit interrupt URB: %s\n",
-			get_usb_statmsg(ret));
+			get_usb_rcmsg(rc));
 		goto error;
 	}
 
 	/* tell the device that the driver is ready */
-	if ((ret = req_submit(cs->bcs, HD_DEVICE_INIT_ACK, 0, 0)) != 0)
+	if ((rc = req_submit(cs->bcs, HD_DEVICE_INIT_ACK, 0, 0)) != 0)
 		goto error;
 
 	/* tell common part that the device is ready */
@@ -2179,6 +2205,8 @@ static int gigaset_probe(struct usb_interface *interface,
 
 	return 0;
 
+allocerr:
+	dev_err(cs->dev, "could not allocate URBs\n");
 error:
 	freeurbs(cs);
 	usb_set_intfdata(interface, NULL);
@@ -2193,19 +2221,34 @@ static void gigaset_disconnect(struct usb_interface *interface)
 {
 	struct cardstate *cs;
 	struct bas_cardstate *ucs;
+	int j;
 
 	cs = usb_get_intfdata(interface);
 
 	ucs = cs->hw.bas;
 
 	dev_info(cs->dev, "disconnecting Gigaset base\n");
+
+	/* mark base as not ready, all channels disconnected */
+	atomic_set(&ucs->basstate, 0);
+
+	/* tell LL all channels are down */
+	//FIXME shouldn't gigaset_stop() do this?
+	for (j = 0; j < 2; ++j)
+		gigaset_bchannel_down(cs->bcs + j);
+
+	/* stop driver (common part) */
 	gigaset_stop(cs);
+
+	/* stop timers and URBs, free ressources */
+	del_timer_sync(&ucs->timer_ctrl);
+	del_timer_sync(&ucs->timer_atrdy);
+	del_timer_sync(&ucs->timer_cmd_in);
 	freeurbs(cs);
 	usb_set_intfdata(interface, NULL);
 	kfree(ucs->rcvbuf);
 	ucs->rcvbuf = NULL;
 	ucs->rcvbuf_size = 0;
-	atomic_set(&ucs->basstate, 0);
 	usb_put_dev(ucs->udev);
 	ucs->interface = NULL;
 	ucs->udev = NULL;
@@ -2277,6 +2320,8 @@ error:	if (cardstate)
  */
 static void __exit bas_gigaset_exit(void)
 {
+	struct bas_cardstate *ucs = cardstate->hw.bas;
+
 	gigaset_blockdriver(driver); /* => probe will fail
 				      * => no gigaset_start any more
 				      */
@@ -2284,14 +2329,26 @@ static void __exit bas_gigaset_exit(void)
 	gigaset_shutdown(cardstate);
 	/* from now on, no isdn callback should be possible */
 
-	if (atomic_read(&cardstate->hw.bas->basstate) & BS_ATOPEN) {
-		gig_dbg(DEBUG_ANY, "closing AT channel");
-		if (req_submit(cardstate->bcs,
-			       HD_CLOSE_ATCHANNEL, 0, BAS_TIMEOUT) >= 0) {
-			/* successfully submitted */
-			//FIXME wait for completion?
-		}
+	/* close all still open channels */
+	if (atomic_read(&ucs->basstate) & BS_B1OPEN) {
+		gig_dbg(DEBUG_INIT, "closing B1 channel");
+		usb_control_msg(ucs->udev, usb_sndctrlpipe(ucs->udev, 0),
+				HD_CLOSE_B1CHANNEL, OUT_VENDOR_REQ, 0, 0,
+				NULL, 0, BAS_TIMEOUT);
+	}
+	if (atomic_read(&ucs->basstate) & BS_B2OPEN) {
+		gig_dbg(DEBUG_INIT, "closing B2 channel");
+		usb_control_msg(ucs->udev, usb_sndctrlpipe(ucs->udev, 0),
+				HD_CLOSE_B2CHANNEL, OUT_VENDOR_REQ, 0, 0,
+				NULL, 0, BAS_TIMEOUT);
+	}
+	if (atomic_read(&ucs->basstate) & BS_ATOPEN) {
+		gig_dbg(DEBUG_INIT, "closing AT channel");
+		usb_control_msg(ucs->udev, usb_sndctrlpipe(ucs->udev, 0),
+				HD_CLOSE_ATCHANNEL, OUT_VENDOR_REQ, 0, 0,
+				NULL, 0, BAS_TIMEOUT);
 	}
+	atomic_set(&ucs->basstate, 0);
 
 	/* deregister this driver with the USB subsystem */
 	usb_deregister(&gigaset_usb_driver);
diff --git a/drivers/isdn/gigaset/common.c b/drivers/isdn/gigaset/common.c
index 749b3da1236e..e55767b2ccd3 100644
--- a/drivers/isdn/gigaset/common.c
+++ b/drivers/isdn/gigaset/common.c
@@ -781,8 +781,7 @@ error:	if (cs)
 }
 EXPORT_SYMBOL_GPL(gigaset_initcs);
 
-/* ReInitialize the b-channel structure */
-/* e.g. called on hangup, disconnect */
+/* ReInitialize the b-channel structure on hangup */
 void gigaset_bcs_reinit(struct bc_state *bcs)
 {
 	struct sk_buff *skb;
diff --git a/drivers/isdn/gigaset/ev-layer.c b/drivers/isdn/gigaset/ev-layer.c
index 1ba3424a286b..18e05c09b71c 100644
--- a/drivers/isdn/gigaset/ev-layer.c
+++ b/drivers/isdn/gigaset/ev-layer.c
@@ -373,6 +373,9 @@ struct reply_t gigaset_tab_cid_m10x[] = /* for M10x */
 
 	{EV_TIMEOUT,  750,750, -1,                  0, 0, {ACT_CONNTIMEOUT}},
 
+	/* B channel closed (general case) */
+	{EV_BC_CLOSED, -1, -1, -1,                 -1,-1, {ACT_NOTIFY_BC_DOWN}}, //FIXME
+
 	/* misc. */
 	{EV_PROTO_L2,  -1, -1, -1,                 -1,-1, {ACT_PROTO_L2}}, //FIXME
 
diff --git a/drivers/isdn/gigaset/gigaset.h b/drivers/isdn/gigaset/gigaset.h
index 9d21ba8757b0..22b9693f7c0a 100644
--- a/drivers/isdn/gigaset/gigaset.h
+++ b/drivers/isdn/gigaset/gigaset.h
@@ -75,7 +75,7 @@ extern int gigaset_debuglevel;	/* "needs" cast to (enum debuglevel) */
  * e.g. 'insmod usb_gigaset.o debug=0x2c' will set DEBUG_OPEN, DEBUG_CMD and
  * DEBUG_INTR.
  */
-enum debuglevel { /* up to 24 bits (atomic_t) */
+enum debuglevel {
 	DEBUG_REG	  = 0x0002, /* serial port I/O register operations */
 	DEBUG_OPEN	  = 0x0004, /* open/close serial port */
 	DEBUG_INTR	  = 0x0008, /* interrupt processing */
@@ -141,7 +141,7 @@ enum debuglevel { /* up to 24 bits (atomic_t) */
 			printk(KERN_DEBUG KBUILD_MODNAME ": " format "\n", \
 			       ## arg); \
 	} while (0)
-#define DEBUG_DEFAULT (DEBUG_INIT | DEBUG_TRANSCMD | DEBUG_CMD | DEBUG_USBREQ)
+#define DEBUG_DEFAULT (DEBUG_TRANSCMD | DEBUG_CMD | DEBUG_USBREQ)
 
 #else
 
@@ -627,8 +627,7 @@ struct gigaset_ops {
 	/* Called by gigaset_freecs() for freeing bcs->hw.xxx */
 	int (*freebcshw)(struct bc_state *bcs);
 
-	/* Called by gigaset_stop() or gigaset_bchannel_down() for resetting
-	   bcs->hw.xxx */
+	/* Called by gigaset_bchannel_down() for resetting bcs->hw.xxx */
 	void (*reinitbcshw)(struct bc_state *bcs);
 
 	/* Called by gigaset_initcs() for setting up cs->hw.xxx */
diff --git a/drivers/isdn/gigaset/i4l.c b/drivers/isdn/gigaset/i4l.c
index 0815dbfb8291..1654fa413575 100644
--- a/drivers/isdn/gigaset/i4l.c
+++ b/drivers/isdn/gigaset/i4l.c
@@ -73,7 +73,7 @@ static int writebuf_from_LL(int driverID, int channel, int ack,
 		len, skblen, (unsigned) skb->head[0], (unsigned) skb->head[1]);
 
 	/* pass to device-specific module */
-	return cs->ops->send_skb(bcs, skb); //FIXME cs->ops->send_skb() must handle !cs->connected correctly
+	return cs->ops->send_skb(bcs, skb);
 }
 
 void gigaset_skb_sent(struct bc_state *bcs, struct sk_buff *skb)
diff --git a/drivers/isdn/gigaset/isocdata.c b/drivers/isdn/gigaset/isocdata.c
index 45f017ed6e8c..8667daaa1a82 100644
--- a/drivers/isdn/gigaset/isocdata.c
+++ b/drivers/isdn/gigaset/isocdata.c
@@ -992,14 +992,18 @@ int gigaset_isoc_send_skb(struct bc_state *bcs, struct sk_buff *skb)
 	int len = skb->len;
 	unsigned long flags;
 
+	spin_lock_irqsave(&bcs->cs->lock, flags);
+	if (!bcs->cs->connected) {
+		spin_unlock_irqrestore(&bcs->cs->lock, flags);
+		return -ENODEV;
+	}
+
 	skb_queue_tail(&bcs->squeue, skb);
 	gig_dbg(DEBUG_ISO, "%s: skb queued, qlen=%d",
 		__func__, skb_queue_len(&bcs->squeue));
 
 	/* tasklet submits URB if necessary */
-	spin_lock_irqsave(&bcs->cs->lock, flags);
-	if (bcs->cs->connected)
-		tasklet_schedule(&bcs->hw.bas->sent_tasklet);
+	tasklet_schedule(&bcs->hw.bas->sent_tasklet);
 	spin_unlock_irqrestore(&bcs->cs->lock, flags);
 
 	return len;	/* ok so far */