USB: serial: add support for multiple read urbs

Add support for multiple read urbs to generic read implementation.

Use a static array of two read urbs for now which is enough to get a
50% throughput increase in one test setup.

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

1 files changed, 8 insertions, 1 deletions

diff --git a/include/linux/usb/serial.h b/include/linux/usb/serial.h
index 8ccd405e9005..4267a9c717ba 100644
--- a/include/linux/usb/serial.h
+++ b/include/linux/usb/serial.h
@@ -58,6 +58,9 @@ enum port_dev_state {
  * @read_urb: pointer to the bulk in struct urb for this port.
  * @bulk_in_endpointAddress: endpoint address for the bulk in pipe for this
  *      port.
+ * @bulk_in_buffers: pointers to the bulk in buffers for this port
+ * @read_urbs: pointers to the bulk in urbs for this port
+ * @read_urbs_free: status bitmap the for bulk in urbs
  * @bulk_out_buffer: pointer to the bulk out buffer for this port.
  * @bulk_out_size: the size of the bulk_out_buffer, in bytes.
  * @write_urb: pointer to the bulk out struct urb for this port.
@@ -98,6 +101,10 @@ struct usb_serial_port {
         struct urb              *read_urb;
         __u8                    bulk_in_endpointAddress;
 
+        unsigned char           *bulk_in_buffers[2];
+        struct urb              *read_urbs[2];
+        unsigned long           read_urbs_free;
+
         unsigned char           *bulk_out_buffer;
         int                     bulk_out_size;
         struct urb              *write_urb;
@@ -338,7 +345,7 @@ extern void usb_serial_generic_disconnect(struct usb_serial *serial);
 extern void usb_serial_generic_release(struct usb_serial *serial);
 extern int usb_serial_generic_register(int debug);
 extern void usb_serial_generic_deregister(void);
-extern int usb_serial_generic_submit_read_urb(struct usb_serial_port *port,
+extern int usb_serial_generic_submit_read_urbs(struct usb_serial_port *port,
                                                  gfp_t mem_flags);
 extern void usb_serial_generic_process_read_urb(struct urb *urb);
 extern int usb_serial_generic_prepare_write_buffer(struct usb_serial_port *port,