1 files changed, 42 insertions, 32 deletions

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index c95f7d8314fc..cb8de8d61265 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -795,41 +795,51 @@ static int gsm_dlci_data_output(struct gsm_mux *gsm, struct gsm_dlci *dlci)
 {
 	struct gsm_msg *msg;
 	u8 *dp;
-	int len, total_size, size;
-	int h = dlci->adaption - 1;
+	int h, len, size;
 
-	total_size = 0;
-	while (1) {
-		len = kfifo_len(&dlci->fifo);
-		if (len == 0)
-			return total_size;
-
-		/* MTU/MRU count only the data bits */
-		if (len > gsm->mtu)
-			len = gsm->mtu;
-
-		size = len + h;
-
-		msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
-		/* FIXME: need a timer or something to kick this so it can't
-		   get stuck with no work outstanding and no buffer free */
-		if (msg == NULL)
-			return -ENOMEM;
-		dp = msg->data;
-		switch (dlci->adaption) {
-		case 1:	/* Unstructured */
-			break;
-		case 2:	/* Unstructed with modem bits.
-		Always one byte as we never send inline break data */
-			*dp++ = (gsm_encode_modem(dlci) << 1) | EA;
-			break;
-		}
-		WARN_ON(kfifo_out_locked(&dlci->fifo, dp , len, &dlci->lock) != len);
-		__gsm_data_queue(dlci, msg);
-		total_size += size;
+	/* for modem bits without break data */
+	h = ((dlci->adaption == 1) ? 0 : 1);
+
+	len = kfifo_len(&dlci->fifo);
+	if (len == 0)
+		return 0;
+
+	/* MTU/MRU count only the data bits but watch adaption mode */
+	if ((len + h) > gsm->mtu)
+		len = gsm->mtu - h;
+
+	size = len + h;
+
+	msg = gsm_data_alloc(gsm, dlci->addr, size, gsm->ftype);
+	/* FIXME: need a timer or something to kick this so it can't
+	 * get stuck with no work outstanding and no buffer free
+	 */
+	if (!msg)
+		return -ENOMEM;
+	dp = msg->data;
+	switch (dlci->adaption) {
+	case 1: /* Unstructured */
+		break;
+	case 2: /* Unstructured with modem bits.
+		 * Always one byte as we never send inline break data
+		 */
+		*dp++ = (gsm_encode_modem(dlci) << 1) | EA;
+		break;
+	default:
+		pr_err("%s: unsupported adaption %d\n", __func__,
+		       dlci->adaption);
+		break;
 	}
+
+	WARN_ON(len != kfifo_out_locked(&dlci->fifo, dp, len,
+		&dlci->lock));
+
+	/* Notify upper layer about available send space. */
+	tty_port_tty_wakeup(&dlci->port);
+
+	__gsm_data_queue(dlci, msg);
 	/* Bytes of data we used up */
-	return total_size;
+	return size;
 }
 
 /**