USB: serial: sierra driver read path bug fix

This patch fixes a problem in function sierra_indat_callback() which
would stop receiving traffic from a modem if a number of URB failures
occur.  Failed URBs are not resubmitted for the next read and there is
only a limited number of URBs allocated for the IN path. After this
number of failures, the receive path stops working on a particular
interface.

Signed-off-by: Elina Pasheva <epasheva@sierrawireless.com>

diff --git a/drivers/usb/serial/sierra.c b/drivers/usb/serial/sierra.c
index 27f41f9..f494c5f 100644 (file)
--- a/drivers/usb/serial/sierra.c
+++ b/drivers/usb/serial/sierra.c
@@ -509,10 +509,10 @@ static void sierra_indat_callback(struct urb *urb)
        unsigned char *data = urb->transfer_buffer;
        int status = urb->status;
 
-       dbg("%s: %p", __func__, urb);
-
        endpoint = usb_pipeendpoint(urb->pipe);
-       port =  urb->context;
+       port = urb->context;
+
+       dev_dbg(&port->dev, "%s: %p\n", __func__, urb);
 
        if (status) {
                dev_dbg(&port->dev, "%s: nonzero status: %d on"
@@ -520,22 +520,28 @@ static void sierra_indat_callback(struct urb *urb)
        } else {
                if (urb->actual_length) {
                        tty = tty_port_tty_get(&port->port);
+
                        tty_buffer_request_room(tty, urb->actual_length);
                        tty_insert_flip_string(tty, data, urb->actual_length);
                        tty_flip_buffer_push(tty);
+
                        tty_kref_put(tty);
-               } else
+                       usb_serial_debug_data(debug, &port->dev, __func__,
+                               urb->actual_length, data);
+               } else {
                        dev_dbg(&port->dev, "%s: empty read urb"
                                " received\n", __func__);
-
-               /* Resubmit urb so we continue receiving */
-               if (port->port.count && status != -ESHUTDOWN && status != -EPERM) {
-                       err = usb_submit_urb(urb, GFP_ATOMIC);
-                       if (err)
-                               dev_err(&port->dev, "resubmit read urb failed."
-                                       "(%d)\n", err);
                }
        }
+
+       /* Resubmit urb so we continue receiving */
+       if (port->port.count && status != -ESHUTDOWN && status != -EPERM) {
+               err = usb_submit_urb(urb, GFP_ATOMIC);
+               if (err)
+                       dev_err(&port->dev, "resubmit read urb failed."
+                               "(%d)\n", err);
+       }
+
        return;
 }