[PATCH] isdn/gigaset: fix possible missing wakeup

Eliminate some possibilities for user processes writing to the Gigaset
character device to be left sleeping indefinitely, by adding wakeup calls
to error paths and properly disposing of pending write requests when the
device is disconnected.

It also removes unnecessary NULL checks before usb_free_urb() and
usb_kill_urb() calls.
Signed-off-by: NTilman Schmidt <tilman@imap.cc>
Acked-by: NKarsten Keil <kkeil@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

drivers/isdn/gigaset/bas-gigaset.c

@@ -1853,20 +1853,24 @@ static int gigaset_write_cmd(struct cardstate *cs,
 {
 	struct cmdbuf_t *cb;
 	unsigned long flags;
-	int status;
+	int rc;
 
 	gigaset_dbg_buffer(atomic_read(&cs->mstate) != MS_LOCKED ?
 			     DEBUG_TRANSCMD : DEBUG_LOCKCMD,
 			   "CMD Transmit", len, buf);
 
-	if (len <= 0)
-		return 0;			/* nothing to do */
+	if (len <= 0) {
+		/* nothing to do */
+		rc = 0;
+		goto notqueued;
+	}
 
 	if (len > IF_WRITEBUF)
 		len = IF_WRITEBUF;
 	if (!(cb = kmalloc(sizeof(struct cmdbuf_t) + len, GFP_ATOMIC))) {
 		dev_err(cs->dev, "%s: out of memory\n", __func__);
-		return -ENOMEM;
+		rc = -ENOMEM;
+		goto notqueued;
 	}
 
 	memcpy(cb->buf, buf, len);
@@ -1891,11 +1895,21 @@ static int gigaset_write_cmd(struct cardstate *cs,
 	if (unlikely(!cs->connected)) {
 		spin_unlock_irqrestore(&cs->lock, flags);
 		gig_dbg(DEBUG_USBREQ, "%s: not connected", __func__);
+		/* flush command queue */
+		spin_lock_irqsave(&cs->cmdlock, flags);
+		while (cs->cmdbuf != NULL)
+			complete_cb(cs);
+		spin_unlock_irqrestore(&cs->cmdlock, flags);
 		return -ENODEV;
 	}
-	status = start_cbsend(cs);
+	rc = start_cbsend(cs);
 	spin_unlock_irqrestore(&cs->lock, flags);
-	return status < 0 ? status : len;
+	return rc < 0 ? rc : len;
+
+notqueued:			/* request handled without queuing */
+	if (wake_tasklet)
+		tasklet_schedule(wake_tasklet);
+	return rc;
 }
 
 /* gigaset_write_room
@@ -1964,20 +1978,15 @@ static int gigaset_freebcshw(struct bc_state *bcs)
 
 	/* 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]);
-		}
+	gig_dbg(DEBUG_INIT, "%s: killing iso URBs", __func__);
+	for (i = 0; i < BAS_OUTURBS; ++i) {
+		usb_kill_urb(ubc->isoouturbs[i].urb);
+		usb_free_urb(ubc->isoouturbs[i].urb);
+	}
+	for (i = 0; i < BAS_INURBS; ++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);
@@ -2099,55 +2108,32 @@ static void freeurbs(struct cardstate *cs)
 	struct bas_bc_state *ubc;
 	int i, j;
 
+	gig_dbg(DEBUG_INIT, "%s: killing URBs", __func__);
 	for (j = 0; j < 2; ++j) {
 		ubc = cs->bcs[j].hw.bas;
-		for (i = 0; i < BAS_OUTURBS; ++i)
-			if (ubc->isoouturbs[i].urb) {
-				usb_kill_urb(ubc->isoouturbs[i].urb);
-				gig_dbg(DEBUG_INIT,
-					"%s: isoc output URB %d/%d unlinked",
-					__func__, j, i);
-				usb_free_urb(ubc->isoouturbs[i].urb);
-				ubc->isoouturbs[i].urb = NULL;
-			}
-		for (i = 0; i < BAS_INURBS; ++i)
-			if (ubc->isoinurbs[i]) {
-				usb_kill_urb(ubc->isoinurbs[i]);
-				gig_dbg(DEBUG_INIT,
-					"%s: isoc input URB %d/%d unlinked",
-					__func__, j, i);
-				usb_free_urb(ubc->isoinurbs[i]);
-				ubc->isoinurbs[i] = NULL;
-			}
-	}
-	if (ucs->urb_int_in) {
-		usb_kill_urb(ucs->urb_int_in);
-		gig_dbg(DEBUG_INIT, "%s: interrupt input URB unlinked",
-			__func__);
-		usb_free_urb(ucs->urb_int_in);
-		ucs->urb_int_in = NULL;
-	}
-	if (ucs->urb_cmd_out) {
-		usb_kill_urb(ucs->urb_cmd_out);
-		gig_dbg(DEBUG_INIT, "%s: command output URB unlinked",
-			__func__);
-		usb_free_urb(ucs->urb_cmd_out);
-		ucs->urb_cmd_out = NULL;
-	}
-	if (ucs->urb_cmd_in) {
-		usb_kill_urb(ucs->urb_cmd_in);
-		gig_dbg(DEBUG_INIT, "%s: command input URB unlinked",
-			__func__);
-		usb_free_urb(ucs->urb_cmd_in);
-		ucs->urb_cmd_in = NULL;
-	}
-	if (ucs->urb_ctrl) {
-		usb_kill_urb(ucs->urb_ctrl);
-		gig_dbg(DEBUG_INIT, "%s: control output URB unlinked",
-			__func__);
-		usb_free_urb(ucs->urb_ctrl);
-		ucs->urb_ctrl = NULL;
+		for (i = 0; i < BAS_OUTURBS; ++i) {
+			usb_kill_urb(ubc->isoouturbs[i].urb);
+			usb_free_urb(ubc->isoouturbs[i].urb);
+			ubc->isoouturbs[i].urb = NULL;
+		}
+		for (i = 0; i < BAS_INURBS; ++i) {
+			usb_kill_urb(ubc->isoinurbs[i]);
+			usb_free_urb(ubc->isoinurbs[i]);
+			ubc->isoinurbs[i] = NULL;
+		}
 	}
+	usb_kill_urb(ucs->urb_int_in);
+	usb_free_urb(ucs->urb_int_in);
+	ucs->urb_int_in = NULL;
+	usb_kill_urb(ucs->urb_cmd_out);
+	usb_free_urb(ucs->urb_cmd_out);
+	ucs->urb_cmd_out = NULL;
+	usb_kill_urb(ucs->urb_cmd_in);
+	usb_free_urb(ucs->urb_cmd_in);
+	ucs->urb_cmd_in = NULL;
+	usb_kill_urb(ucs->urb_ctrl);
+	usb_free_urb(ucs->urb_ctrl);
+	ucs->urb_ctrl = NULL;
 }
 
 /* gigaset_probe