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USB: serial: keyspan_pda: fix data loss on receive throttling

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Killing the interrupt-in urb when the line disciple requests throttling
may lead to data loss if an ongoing transfer is cancelled.

Instead set a flag to prevent the completion handler from resubmitting
the urb until the port is unthrottled.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>
This commit is contained in:
Johan Hovold 2026-07-08 16:31:35 +02:00
parent a13c140cc2
commit 42a97c0480
1 changed files with 35 additions and 9 deletions
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44
drivers/usb/serial/keyspan_pda.c
View File

@ -33,6 +33,8 @@ struct keyspan_pda_private {
struct work_struct unthrottle_work;
struct usb_serial *serial;
struct usb_serial_port *port;
bool throttled;
bool throttle_req;
};
static int keyspan_pda_write_start(struct usb_serial_port *port);
@ -148,6 +150,7 @@ static void keyspan_pda_rx_interrupt(struct urb *urb)
int retval;
int status = urb->status;
struct keyspan_pda_private *priv;
bool throttled = false;
unsigned long flags;
priv = usb_get_serial_port_data(port);
@ -209,16 +212,24 @@ static void keyspan_pda_rx_interrupt(struct urb *urb)
}
exit:
retval = usb_submit_urb(urb, GFP_ATOMIC);
if (retval)
dev_err(&port->dev,
"%s - usb_submit_urb failed with result %d\n",
__func__, retval);
spin_lock_irqsave(&port->lock, flags);
if (priv->throttle_req) {
priv->throttled = true;
throttled = true;
}
spin_unlock_irqrestore(&port->lock, flags);
if (!throttled) {
retval = usb_submit_urb(urb, GFP_ATOMIC);
if (retval)
dev_err(&port->dev, "failed to resubmit in urb: %d\n", retval);
}
}
static void keyspan_pda_rx_throttle(struct tty_struct *tty)
{
struct usb_serial_port *port = tty->driver_data;
struct keyspan_pda_private *priv = usb_get_serial_port_data(port);
/*
* Stop receiving characters. We just turn off the URB request, and
@ -228,16 +239,29 @@ static void keyspan_pda_rx_throttle(struct tty_struct *tty)
* send an XOFF, although it might make sense to foist that off upon
* the device too.
*/
usb_kill_urb(port->interrupt_in_urb);
spin_lock_irq(&port->lock);
priv->throttle_req = true;
spin_unlock_irq(&port->lock);
}
static void keyspan_pda_rx_unthrottle(struct tty_struct *tty)
{
struct usb_serial_port *port = tty->driver_data;
struct keyspan_pda_private *priv = usb_get_serial_port_data(port);
bool throttled;
int ret;
/* just restart the receive interrupt URB */
if (usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL))
dev_dbg(&port->dev, "usb_submit_urb(read urb) failed\n");
spin_lock_irq(&port->lock);
throttled = priv->throttled;
priv->throttled = false;
priv->throttle_req = false;
spin_unlock_irq(&port->lock);
if (throttled) {
ret = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
if (ret)
dev_err(&port->dev, "failed to submit in urb: %d\n", ret);
}
}
static speed_t keyspan_pda_setbaud(struct usb_serial *serial, speed_t baud)
@ -577,6 +601,8 @@ static int keyspan_pda_open(struct tty_struct *tty,
spin_lock_irq(&port->lock);
priv->tx_room = rc;
priv->throttled = false;
priv->throttle_req = false;
spin_unlock_irq(&port->lock);
rc = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);