struct_usb_sg_request(9) centos man page | unix.com

STRUCT 
USB_SG_REQUES(9) 				  Host-Side Data Types and Macro				   STRUCT USB_SG_REQUES(9)

NAME
       struct_usb_sg_request - support for scatter/gather I/O

SYNOPSIS
       struct usb_sg_request {
	 int status;
	 size_t bytes;
       };

MEMBERS
       status
	   zero indicates success, else negative errno

       bytes
	   counts bytes transferred.

DESCRIPTION
       These requests are initialized using usb_sg_init, and then are used as request handles passed to usb_sg_wait or usb_sg_cancel. Most members
       of the request object aren't for driver access.

       The status and bytecount values are valid only after usb_sg_wait returns. If the status is zero, then the bytecount matches the total from
       the request.

       After an error completion, drivers may need to clear a halt condition on the endpoint.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014						   STRUCT USB_SG_REQUES(9)