[PATCH 4.9 06/68] USB: serial: ir-usb: fix IrLAP framing

Greg Kroah-Hartman
2020-02-03T16:26:21Z

From: Johan Hovold <johan@kernel.org>

commit 38c0d5bdf4973f9f5a888166e9d3e9ed0d32057a upstream.

Commit f4a4cbb2047e ("USB: ir-usb: reimplement using generic framework")
switched to using the generic write implementation which may combine
multiple write requests into larger transfers. This can break the IrLAP
protocol where end-of-frame is determined using the USB short packet
mechanism, for example, if multiple frames are sent in rapid succession.

Fixes: f4a4cbb2047e ("USB: ir-usb: reimplement using generic framework")
Cc: stable <stable@vger.kernel.org> # 2.6.35
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/serial/ir-usb.c | 113 +++++++++++++++++++++++++++++++++++---------
1 file changed, 91 insertions(+), 22 deletions(-)

--- a/drivers/usb/serial/ir-usb.c
+++ b/drivers/usb/serial/ir-usb.c
@@ -49,9 +49,10 @@ static int buffer_size;
static int xbof = -1;

static int ir_startup (struct usb_serial *serial);
-static int ir_open(struct tty_struct *tty, struct usb_serial_port *port);
-static int ir_prepare_write_buffer(struct usb_serial_port *port,
- void *dest, size_t size);
+static int ir_write(struct tty_struct *tty, struct usb_serial_port *port,
+ const unsigned char *buf, int count);
+static int ir_write_room(struct tty_struct *tty);
+static void ir_write_bulk_callback(struct urb *urb);
static void ir_process_read_urb(struct urb *urb);
static void ir_set_termios(struct tty_struct *tty,
struct usb_serial_port *port, struct ktermios *old_termios);
@@ -81,8 +82,9 @@ static struct usb_serial_driver ir_devic
.num_ports = 1,
.set_termios = ir_set_termios,
.attach = ir_startup,
- .open = ir_open,
- .prepare_write_buffer = ir_prepare_write_buffer,
+ .write = ir_write,
+ .write_room = ir_write_room,
+ .write_bulk_callback = ir_write_bulk_callback,
.process_read_urb = ir_process_read_urb,
};

@@ -255,35 +257,102 @@ static int ir_startup(struct usb_serial
return 0;
}

-static int ir_open(struct tty_struct *tty, struct usb_serial_port *port)
+static int ir_write(struct tty_struct *tty, struct usb_serial_port *port,
+ const unsigned char *buf, int count)
{
- int i;
+ struct urb *urb = NULL;
+ unsigned long flags;
+ int ret;

- for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i)
- port->write_urbs[i]->transfer_flags = URB_ZERO_PACKET;
+ if (port->bulk_out_size == 0)
+ return -EINVAL;

- /* Start reading from the device */
- return usb_serial_generic_open(tty, port);
-}
+ if (count == 0)
+ return 0;

-static int ir_prepare_write_buffer(struct usb_serial_port *port,
- void *dest, size_t size)
-{
- unsigned char *buf = dest;
- int count;
+ count = min(count, port->bulk_out_size - 1);
+
+ spin_lock_irqsave(&port->lock, flags);
+ if (__test_and_clear_bit(0, &port->write_urbs_free)) {
+ urb = port->write_urbs[0];
+ port->tx_bytes += count;
+ }
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ if (!urb)
+ return 0;

/*
* The first byte of the packet we send to the device contains an
- * inbound header which indicates an additional number of BOFs and
+ * outbound header which indicates an additional number of BOFs and
* a baud rate change.
*
* See section 5.4.2.2 of the USB IrDA spec.
*/
- *buf = ir_xbof | ir_baud;
+ *(u8 *)urb->transfer_buffer = ir_xbof | ir_baud;
+
+ memcpy(urb->transfer_buffer + 1, buf, count);
+
+ urb->transfer_buffer_length = count + 1;
+ urb->transfer_flags = URB_ZERO_PACKET;
+
+ ret = usb_submit_urb(urb, GFP_ATOMIC);
+ if (ret) {
+ dev_err(&port->dev, "failed to submit write urb: %d\n", ret);
+
+ spin_lock_irqsave(&port->lock, flags);
+ __set_bit(0, &port->write_urbs_free);
+ port->tx_bytes -= count;
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ return ret;
+ }
+
+ return count;
+}
+
+static void ir_write_bulk_callback(struct urb *urb)
+{
+ struct usb_serial_port *port = urb->context;
+ int status = urb->status;
+ unsigned long flags;
+
+ spin_lock_irqsave(&port->lock, flags);
+ __set_bit(0, &port->write_urbs_free);
+ port->tx_bytes -= urb->transfer_buffer_length - 1;
+ spin_unlock_irqrestore(&port->lock, flags);
+
+ switch (status) {
+ case 0:
+ break;
+ case -ENOENT:
+ case -ECONNRESET:
+ case -ESHUTDOWN:
+ dev_dbg(&port->dev, "write urb stopped: %d\n", status);
+ return;
+ case -EPIPE:
+ dev_err(&port->dev, "write urb stopped: %d\n", status);
+ return;
+ default:
+ dev_err(&port->dev, "nonzero write-urb status: %d\n", status);
+ break;
+ }
+
+ usb_serial_port_softint(port);
+}
+
+static int ir_write_room(struct tty_struct *tty)
+{
+ struct usb_serial_port *port = tty->driver_data;
+ int count = 0;
+
+ if (port->bulk_out_size == 0)
+ return 0;
+
+ if (test_bit(0, &port->write_urbs_free))
+ count = port->bulk_out_size - 1;

- count = kfifo_out_locked(&port->write_fifo, buf + 1, size - 1,
- &port->lock);
- return count + 1;
+ return count;
}

static void ir_process_read_urb(struct urb *urb)