1 files changed, 79 insertions, 11 deletions

diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 5d2bb4d95..f6d2be13b 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -411,6 +411,27 @@ static int gsm_read_ea(unsigned int *val, u8 c)
 }
 
 /**
+ *	gsm_read_ea_val	-	read a value until EA
+ *	@val: variable holding value
+ *	@data: buffer of data
+ *	@dlen: length of data
+ *
+ *	Processes an EA value. Updates the passed variable and
+ *	returns the processed data length.
+ */
+static unsigned int gsm_read_ea_val(unsigned int *val, const u8 *data, int dlen)
+{
+	unsigned int len = 0;
+
+	for (; dlen > 0; dlen--) {
+		len++;
+		if (gsm_read_ea(val, *data++))
+			break;
+	}
+	return len;
+}
+
+/**
  *	gsm_encode_modem	-	encode modem data bits
  *	@dlci: DLCI to encode from
  *
@@ -658,6 +679,37 @@ static struct gsm_msg *gsm_data_alloc(struct gsm_mux *gsm, u8 addr, int len,
 }
 
 /**
+ *	gsm_is_flow_ctrl_msg	-	checks if flow control message
+ *	@msg: message to check
+ *
+ *	Returns true if the given message is a flow control command of the
+ *	control channel. False is returned in any other case.
+ */
+static bool gsm_is_flow_ctrl_msg(struct gsm_msg *msg)
+{
+	unsigned int cmd;
+
+	if (msg->addr > 0)
+		return false;
+
+	switch (msg->ctrl & ~PF) {
+	case UI:
+	case UIH:
+		cmd = 0;
+		if (gsm_read_ea_val(&cmd, msg->data + 2, msg->len - 2) < 1)
+			break;
+		switch (cmd & ~PF) {
+		case CMD_FCOFF:
+		case CMD_FCON:
+			return true;
+		}
+		break;
+	}
+
+	return false;
+}
+
+/**
  *	gsm_data_kick		-	poke the queue
  *	@gsm: GSM Mux
  *
@@ -675,7 +727,7 @@ static void gsm_data_kick(struct gsm_mux *gsm, struct gsm_dlci *dlci)
 	int len;
 
 	list_for_each_entry_safe(msg, nmsg, &gsm->tx_list, list) {
-		if (gsm->constipated && msg->addr)
+		if (gsm->constipated && !gsm_is_flow_ctrl_msg(msg))
 			continue;
 		if (gsm->encoding != 0) {
 			gsm->txframe[0] = GSM1_SOF;
@@ -1330,7 +1382,7 @@ static void gsm_control_retransmit(struct timer_list *t)
 	spin_lock_irqsave(&gsm->control_lock, flags);
 	ctrl = gsm->pending_cmd;
 	if (ctrl) {
-		if (gsm->cretries == 0) {
+		if (gsm->cretries == 0 || !gsm->dlci[0] || gsm->dlci[0]->dead) {
 			gsm->pending_cmd = NULL;
 			ctrl->error = -ETIMEDOUT;
 			ctrl->done = 1;
@@ -1482,8 +1534,8 @@ static void gsm_dlci_t1(struct timer_list *t)
 
 	switch (dlci->state) {
 	case DLCI_OPENING:
-		dlci->retries--;
 		if (dlci->retries) {
+			dlci->retries--;
 			gsm_command(dlci->gsm, dlci->addr, SABM|PF);
 			mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
 		} else if (!dlci->addr && gsm->control == (DM | PF)) {
@@ -1498,8 +1550,8 @@ static void gsm_dlci_t1(struct timer_list *t)
 
 		break;
 	case DLCI_CLOSING:
-		dlci->retries--;
 		if (dlci->retries) {
+			dlci->retries--;
 			gsm_command(dlci->gsm, dlci->addr, DISC|PF);
 			mod_timer(&dlci->t1, jiffies + gsm->t1 * HZ / 100);
 		} else
@@ -1840,7 +1892,7 @@ static void gsm_queue(struct gsm_mux *gsm)
 			goto invalid;
 #endif
 		if (dlci == NULL || dlci->state != DLCI_OPEN) {
-			gsm_command(gsm, address, DM|PF);
+			gsm_response(gsm, address, DM|PF);
 			return;
 		}
 		dlci->data(dlci, gsm->buf, gsm->len);
@@ -2467,11 +2519,24 @@ static ssize_t gsmld_read(struct tty_struct *tty, struct file *file,
 static ssize_t gsmld_write(struct tty_struct *tty, struct file *file,
 			   const unsigned char *buf, size_t nr)
 {
-	int space = tty_write_room(tty);
+	struct gsm_mux *gsm = tty->disc_data;
+	unsigned long flags;
+	int space;
+	int ret;
+
+	if (!gsm)
+		return -ENODEV;
+
+	ret = -ENOBUFS;
+	spin_lock_irqsave(&gsm->tx_lock, flags);
+	space = tty_write_room(tty);
 	if (space >= nr)
-		return tty->ops->write(tty, buf, nr);
-	set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
-	return -ENOBUFS;
+		ret = tty->ops->write(tty, buf, nr);
+	else
+		set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+	spin_unlock_irqrestore(&gsm->tx_lock, flags);
+
+	return ret;
 }
 
 /**
@@ -2496,12 +2561,15 @@ static __poll_t gsmld_poll(struct tty_struct *tty, struct file *file,
 
 	poll_wait(file, &tty->read_wait, wait);
 	poll_wait(file, &tty->write_wait, wait);
+
+	if (gsm->dead)
+		mask |= EPOLLHUP;
 	if (tty_hung_up_p(file))
 		mask |= EPOLLHUP;
+	if (test_bit(TTY_OTHER_CLOSED, &tty->flags))
+		mask |= EPOLLHUP;
 	if (!tty_is_writelocked(tty) && tty_write_room(tty) > 0)
 		mask |= EPOLLOUT | EPOLLWRNORM;
-	if (gsm->dead)
-		mask |= EPOLLHUP;
 	return mask;
 }