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>

1 files changed, 17 insertions, 11 deletions

diff --git a/drivers/usb/serial/sierra.c b/drivers/usb/serial/sierra.c
index 27f41f95aefb..f494c5f659e2 100644
--- 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;
 }