linux: stop driver from submitting URBs once device has been disconne…

…cted

This fixes and issues where the drive would continue to submit URBs even after
the device was unplugged, and the usb_device was freed from the usb core causing
kernel panics.

linux/kernel/bladeRF.c

@@ -22,6 +22,7 @@ typedef struct {
     struct usb_interface *interface;
 
     int                   intnum;
+    int                   disconnecting;
 
     int                   rx_en;
     spinlock_t            data_in_lock;
@@ -255,6 +256,9 @@ static int enable_rx(bladerf_device_t *dev) {
     if (dev->intnum != 1)
         return -1;
 
+    if (dev->disconnecting)
+        return -ENODEV;
+
     ret = __bladerf_snd_cmd(dev, BLADE_USB_CMD_RF_RX, &val, sizeof(val));
     if (ret < 0)
         goto err_out;
@@ -285,6 +289,9 @@ static ssize_t bladerf_read(struct file *file, char __user *buf, size_t count, l
         return -1;
     }
 
+    if (dev->disconnecting)
+        return -ENODEV;
+
     if (!dev->rx_en) {
         if (enable_rx(dev)) {
             return -EINVAL;
@@ -365,7 +372,8 @@ static void __bladeRF_write_cb(struct urb *urb)
     usb_unanchor_urb(urb);
 
     atomic_dec(&dev->data_out_inflight);
-    __submit_tx_urb(dev);
+    if (dev->tx_en)
+        __submit_tx_urb(dev);
     dev->bytes += DATA_BUF_SZ;
     wake_up_interruptible(&dev->data_out_wait);
 }
@@ -1040,6 +1048,7 @@ static int bladerf_probe(struct usb_interface *interface,
     dev->intnum = 0;
     dev->bytes = 0;
     dev->debug = 0;
+    dev->disconnecting = 0;
 
     atomic_set(&dev->data_in_inflight, 0);
     atomic_set(&dev->data_out_inflight, 0);
@@ -1076,6 +1085,13 @@ static void bladerf_disconnect(struct usb_interface *interface)
 
     dev = usb_get_intfdata(interface);
 
+    dev->disconnecting = 1;
+    dev->tx_en = 0;
+    dev->rx_en = 0;
+
+    usb_kill_anchored_urbs(&dev->data_out_anchor);
+    usb_kill_anchored_urbs(&dev->data_in_anchor);
+
     bladerf_stop(dev);
 
     usb_deregister_dev(interface, &bladerf_class);