[PATCH] USB: serial: digi_acceleport: fix hard lockup on disconnect

[Johan Hovold <johan@kernel.org>]

If submitting the OOB write urb fails persistently (e.g if the device is
being disconnected) the driver would loop indefinitely with interrupts
disabled.

Check for urb submission errors when sending OOB commands to avoid
hanging if, for example, open(), set_termios() or close() races with a
physical disconnect.

This is issue was flagged by Sashiko when reviewing an unrelated change
to the driver.

Link: https://sashiko.dev/#/patchset/20260610132232.356139-1-johan%40kernel.org?part=1
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/digi_acceleport.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/serial/digi_acceleport.c b/drivers/usb/serial/digi_acceleport.c
index 6899aebfd6ae..88c61030982a 100644
--- a/drivers/usb/serial/digi_acceleport.c
+++ b/drivers/usb/serial/digi_acceleport.c
@@ -392,12 +392,14 @@ static int digi_write_oob_command(struct usb_serial_port *port,
 			len &= ~3;
 		memcpy(oob_port->write_urb->transfer_buffer, buf, len);
 		oob_port->write_urb->transfer_buffer_length = len;
+
 		ret = usb_submit_urb(oob_port->write_urb, GFP_ATOMIC);
-		if (ret == 0) {
-			oob_priv->dp_write_urb_in_use = 1;
-			count -= len;
-			buf += len;
-		}
+		if (ret)
+			break;
+
+		oob_priv->dp_write_urb_in_use = 1;
+		count -= len;
+		buf += len;
 	}
 	spin_unlock_irqrestore(&oob_priv->dp_port_lock, flags);
 	if (ret)
-- 
2.53.0