[PATCH v2 1/2] hso: remove unused workqueue

[PATCH v2 1/2] hso: remove unused workqueue

[Olivier Sobrie]

The workqueue "retry_unthrottle_workqueue" is not scheduled anywhere
in the code. So, remove it.

Signed-off-by: Olivier Sobrie <olivier@sobrie.be>
---
 drivers/net/usb/hso.c |   12 ------------
 1 file changed, 12 deletions(-)

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index a3a0586..9ca2b41 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -261,7 +261,6 @@ struct hso_serial {
 	u16  curr_rx_urb_offset;
 	u8   rx_urb_filled[MAX_RX_URBS];
 	struct tasklet_struct unthrottle_tasklet;
-	struct work_struct    retry_unthrottle_workqueue;
 };
 
 struct hso_device {
@@ -1252,14 +1251,6 @@ static	void hso_unthrottle(struct tty_struct *tty)
 	tasklet_hi_schedule(&serial->unthrottle_tasklet);
 }
 
-static void hso_unthrottle_workfunc(struct work_struct *work)
-{
-	struct hso_serial *serial =
-	    container_of(work, struct hso_serial,
-			 retry_unthrottle_workqueue);
-	hso_unthrottle_tasklet(serial);
-}
-
 /* open the requested serial port */
 static int hso_serial_open(struct tty_struct *tty, struct file *filp)
 {
@@ -1295,8 +1286,6 @@ static int hso_serial_open(struct tty_struct *tty, struct file *filp)
 		tasklet_init(&serial->unthrottle_tasklet,
 			     (void (*)(unsigned long))hso_unthrottle_tasklet,
 			     (unsigned long)serial);
-		INIT_WORK(&serial->retry_unthrottle_workqueue,
-			  hso_unthrottle_workfunc);
 		result = hso_start_serial_device(serial->parent, GFP_KERNEL);
 		if (result) {
 			hso_stop_serial_device(serial->parent);
@@ -1345,7 +1334,6 @@ static void hso_serial_close(struct tty_struct *tty, struct file *filp)
 		if (!usb_gone)
 			hso_stop_serial_device(serial->parent);
 		tasklet_kill(&serial->unthrottle_tasklet);
-		cancel_work_sync(&serial->retry_unthrottle_workqueue);
 	}
 
 	if (!usb_gone)
-- 
1.7.9.5

[PATCH v2 2/2] hso: fix deadlock when receiving bursts of data

[Olivier Sobrie]

When the module sends bursts of data, sometimes a deadlock happens in
the hso driver when the tty buffer doesn't get the chance to be flushed
quickly enough.

Remove the endless while loop in function put_rxbuf_data() which is
called by the urb completion handler.
If there isn't enough room in the tty buffer, discards all the data
received in the URB.

Cc: David Miller <davem@davemloft.net>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
Cc: Dan Williams <dcbw@redhat.com>
Cc: Jan Dumon <j.dumon@option.com>
Signed-off-by: Olivier Sobrie <olivier@sobrie.be>
---
Changes in v2:
 - remove the unthrottle timer added in the previous patch version
 - drop entire rx urb data if there is not enough space in tty buffer
 - remove variable curr_rx_urb_offset from hso_serial structure

 drivers/net/usb/hso.c |   38 +++++++++++++++++---------------------
 1 file changed, 17 insertions(+), 21 deletions(-)

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index 9ca2b41..a4272ed 100644
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -258,7 +258,6 @@ struct hso_serial {
 	 * so as not to drop characters on the floor.
 	 */
 	int  curr_rx_urb_idx;
-	u16  curr_rx_urb_offset;
 	u8   rx_urb_filled[MAX_RX_URBS];
 	struct tasklet_struct unthrottle_tasklet;
 };
@@ -2001,8 +2000,7 @@ static void ctrl_callback(struct urb *urb)
 static int put_rxbuf_data(struct urb *urb, struct hso_serial *serial)
 {
 	struct tty_struct *tty;
-	int write_length_remaining = 0;
-	int curr_write_len;
+	int count;
 
 	/* Sanity check */
 	if (urb == NULL || serial == NULL) {
@@ -2012,29 +2010,28 @@ static int put_rxbuf_data(struct urb *urb, struct hso_serial *serial)
 
 	tty = tty_port_tty_get(&serial->port);
 
+	if (tty && test_bit(TTY_THROTTLED, &tty->flags)) {
+		tty_kref_put(tty);
+		return -1;
+	}
+
 	/* Push data to tty */
-	write_length_remaining = urb->actual_length -
-		serial->curr_rx_urb_offset;
 	D1("data to push to tty");
-	while (write_length_remaining) {
-		if (tty && test_bit(TTY_THROTTLED, &tty->flags)) {
-			tty_kref_put(tty);
-			return -1;
-		}
-		curr_write_len = tty_insert_flip_string(&serial->port,
-			urb->transfer_buffer + serial->curr_rx_urb_offset,
-			write_length_remaining);
-		serial->curr_rx_urb_offset += curr_write_len;
-		write_length_remaining -= curr_write_len;
+	count = tty_buffer_request_room(&serial->port, urb->actual_length);
+	if (count >= urb->actual_length) {
+		tty_insert_flip_string(&serial->port, urb->transfer_buffer,
+				       urb->actual_length);
 		tty_flip_buffer_push(&serial->port);
+	} else {
+		dev_warn(&serial->parent->usb->dev,
+			 "dropping data, %d bytes lost\n", urb->actual_length);
 	}
+
 	tty_kref_put(tty);
 
-	if (write_length_remaining == 0) {
-		serial->curr_rx_urb_offset = 0;
-		serial->rx_urb_filled[hso_urb_to_index(serial, urb)] = 0;
-	}
-	return write_length_remaining;
+	serial->rx_urb_filled[hso_urb_to_index(serial, urb)] = 0;
+
+	return 0;
 }
 
 
@@ -2205,7 +2202,6 @@ static int hso_stop_serial_device(struct hso_device *hso_dev)
 		}
 	}
 	serial->curr_rx_urb_idx = 0;
-	serial->curr_rx_urb_offset = 0;
 
 	if (serial->tx_urb)
 		usb_kill_urb(serial->tx_urb);
-- 
1.7.9.5

Re: [PATCH v2 2/2] hso: fix deadlock when receiving bursts of data

[One Thousand Gnomes]

On Mon, 14 Jul 2014 12:08:50 +0200
Olivier Sobrie <olivier-Ui3EtX6WB9GzQB+pC5nmwQ@public.gmane.org> wrote:

> When the module sends bursts of data, sometimes a deadlock happens in
> the hso driver when the tty buffer doesn't get the chance to be flushed
> quickly enough.
> 
> Remove the endless while loop in function put_rxbuf_data() which is
> called by the urb completion handler.
> If there isn't enough room in the tty buffer, discards all the data
> received in the URB.
> 
> Cc: David Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
> Cc: David Laight <David.Laight-ZS65k/vG3HxXrIkS9f7CXA@public.gmane.org>
> Cc: One Thousand Gnomes <gnomes-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>
> Cc: Dan Williams <dcbw-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> Cc: Jan Dumon <j.dumon-x9gZzRpC1QbQT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Olivier Sobrie <olivier-Ui3EtX6WB9GzQB+pC5nmwQ@public.gmane.org>

Acked-by: Alan Cox <alan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
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Re: [PATCH v2 1/2] hso: remove unused workqueue

[David Miller]

From: Olivier Sobrie <olivier@sobrie.be>
Date: Mon, 14 Jul 2014 12:08:49 +0200

> The workqueue "retry_unthrottle_workqueue" is not scheduled anywhere
> in the code. So, remove it.
> 
> Signed-off-by: Olivier Sobrie <olivier@sobrie.be>

Applied.

Re: [PATCH v2 2/2] hso: fix deadlock when receiving bursts of data

[David Miller]

From: Olivier Sobrie <olivier-Ui3EtX6WB9GzQB+pC5nmwQ@public.gmane.org>
Date: Mon, 14 Jul 2014 12:08:50 +0200

> When the module sends bursts of data, sometimes a deadlock happens in
> the hso driver when the tty buffer doesn't get the chance to be flushed
> quickly enough.
> 
> Remove the endless while loop in function put_rxbuf_data() which is
> called by the urb completion handler.
> If there isn't enough room in the tty buffer, discards all the data
> received in the URB.
> 
> Cc: David Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
> Cc: David Laight <David.Laight-ZS65k/vG3HxXrIkS9f7CXA@public.gmane.org>
> Cc: One Thousand Gnomes <gnomes-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>
> Cc: Dan Williams <dcbw-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> Cc: Jan Dumon <j.dumon-x9gZzRpC1QbQT0dZR+AlfA@public.gmane.org>
> Signed-off-by: Olivier Sobrie <olivier-Ui3EtX6WB9GzQB+pC5nmwQ@public.gmane.org>
> ---
> Changes in v2:
>  - remove the unthrottle timer added in the previous patch version
>  - drop entire rx urb data if there is not enough space in tty buffer
>  - remove variable curr_rx_urb_offset from hso_serial structure

Applied, thanks.
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