Subject: patch "USB: serial: ir-usb: fix IrLAP framing" added to usb-testing
To:     johan@kernel.org, gregkh@linuxfoundation.org,
        stable@vger.kernel.org
From:   <gregkh@linuxfoundation.org>
Date:   Mon, 27 Jan 2020 10:22:11 +0100
Message-ID: <15801169313126@kroah.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=ANSI_X3.4-1968
Content-Transfer-Encoding: 8bit
Sender: stable-owner@vger.kernel.org
Precedence: bulk


This is a note to let you know that I've just added the patch titled

    USB: serial: ir-usb: fix IrLAP framing

to my usb git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-testing branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will be merged to the usb-next branch sometime soon,
after it passes testing, and the merge window is open.

If you have any questions about this process, please let me know.


From 38c0d5bdf4973f9f5a888166e9d3e9ed0d32057a Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Wed, 22 Jan 2020 11:15:28 +0100
Subject: USB: serial: ir-usb: fix IrLAP framing

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

diff --git a/drivers/usb/serial/ir-usb.c b/drivers/usb/serial/ir-usb.c
index 26eab1307165..627bea7e6cfb 100644
--- a/drivers/usb/serial/ir-usb.c
+++ b/drivers/usb/serial/ir-usb.c
@@ -45,9 +45,10 @@ 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);
@@ -77,8 +78,9 @@ static struct usb_serial_driver ir_device = {
 	.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,
 };
 
@@ -254,35 +256,102 @@ static int ir_startup(struct usb_serial *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)
-- 
2.25.0