USB: ir-usb: fix set_termios race

Use dynamically allocated urb for baudrate changes rather than
unconditionally submitting the port write urb which may already be in
use.

Compile-only tested.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 47 insertions, 16 deletions

diff --git a/drivers/usb/serial/ir-usb.c b/drivers/usb/serial/ir-usb.c
index aaebb70aca59..d8490eaeb234 100644
--- a/drivers/usb/serial/ir-usb.c
+++ b/drivers/usb/serial/ir-usb.c
@@ -469,9 +469,23 @@ static void ir_read_bulk_callback(struct urb *urb)
         return;
 }
 
+static void ir_set_termios_callback(struct urb *urb)
+{
+        struct usb_serial_port *port = urb->context;
+        int status = urb->status;
+
+        dbg("%s - port %d", __func__, port->number);
+
+        kfree(urb->transfer_buffer);
+
+        if (status)
+                dbg("%s - non-zero urb status: %d", __func__, status);
+}
+
 static void ir_set_termios(struct tty_struct *tty,
                 struct usb_serial_port *port, struct ktermios *old_termios)
 {
+        struct urb *urb;
         unsigned char *transfer_buffer;
         int result;
         speed_t baud;
@@ -525,35 +539,52 @@ static void ir_set_termios(struct tty_struct *tty,
         else
                 ir_xbof = ir_xbof_change(xbof) ;
 
-        /* FIXME need to check to see if our write urb is busy right
-         * now, or use a urb pool.
-         *
+        /* Only speed changes are supported */
+        tty_termios_copy_hw(tty->termios, old_termios);
+        tty_encode_baud_rate(tty, baud, baud);
+
+        /*
          * send the baud change out on an "empty" data packet
          */
-        transfer_buffer = port->write_urb->transfer_buffer;
+        urb = usb_alloc_urb(0, GFP_KERNEL);
+        if (!urb) {
+                dev_err(&port->dev, "%s - no more urbs\n", __func__);
+                return;
+        }
+        transfer_buffer = kmalloc(1, GFP_KERNEL);
+        if (!transfer_buffer) {
+                dev_err(&port->dev, "%s - out of memory\n", __func__);
+                goto err_buf;
+        }
+
         *transfer_buffer = ir_xbof | ir_baud;
 
         usb_fill_bulk_urb(
-                port->write_urb,
+                urb,
                 port->serial->dev,
                 usb_sndbulkpipe(port->serial->dev,
                         port->bulk_out_endpointAddress),
-                port->write_urb->transfer_buffer,
+                transfer_buffer,
                 1,
-                ir_write_bulk_callback,
+                ir_set_termios_callback,
                 port);
 
-        port->write_urb->transfer_flags = URB_ZERO_PACKET;
+        urb->transfer_flags = URB_ZERO_PACKET;
 
-        result = usb_submit_urb(port->write_urb, GFP_KERNEL);
-        if (result)
-                dev_err(&port->dev,
-                                "%s - failed submitting write urb, error %d\n",
-                                __func__, result);
+        result = usb_submit_urb(urb, GFP_KERNEL);
+        if (result) {
+                dev_err(&port->dev, "%s - failed to submit urb: %d\n",
+                                                        __func__, result);
+                goto err_subm;
+        }
 
-        /* Only speed changes are supported */
-        tty_termios_copy_hw(tty->termios, old_termios);
-        tty_encode_baud_rate(tty, baud, baud);
+        usb_free_urb(urb);
+
+        return;
+err_subm:
+        kfree(transfer_buffer);
+err_buf:
+        usb_free_urb(urb);
 }
 
 static int __init ir_init(void)