usb_get_from_anchor(9) [centos man page]

USB_GET_FROM_ANCHOR(9)						   USB Core APIs					    USB_GET_FROM_ANCHOR(9)

NAME

       usb_get_from_anchor - get an anchor's oldest urb

SYNOPSIS

       struct urb * usb_get_from_anchor(struct usb_anchor * anchor);

ARGUMENTS

       anchor
	   the anchor whose urb you want

DESCRIPTION

       This will take the oldest urb from an anchor, unanchor and return it

RETURN

       The oldest urb from anchor, or NULL if anchor has no urbs associated with it.

COPYRIGHT

Kernel Hackers Manual 3.10					     June 2014						    USB_GET_FROM_ANCHOR(9)

USB_POISON_URB(9)						   USB Core APIs						 USB_POISON_URB(9)

NAME

       usb_poison_urb - reliably kill a transfer and prevent further use of an URB

SYNOPSIS

       void usb_poison_urb(struct urb * urb);

ARGUMENTS

       urb
	   pointer to URB describing a previously submitted request, may be NULL

DESCRIPTION

       This routine cancels an in-progress request. It is guaranteed that upon return all completion handlers will have finished and the URB will
       be totally idle and cannot be reused. These features make this an ideal way to stop I/O in a disconnect callback. If the request has not
       already finished or been unlinked the completion handler will see urb->status == -ENOENT.

       After and while the routine runs, attempts to resubmit the URB will fail with error -EPERM. Thus even if the URB's completion handler
       always tries to resubmit, it will not succeed and the URB will become idle.

       The URB must not be deallocated while this routine is running. In particular, when a driver calls this routine, it must insure that the
       completion handler cannot deallocate the URB.

       This routine may not be used in an interrupt context (such as a bottom half or a completion handler), or when holding a spinlock, or in
       other situations where the caller can't schedule.

       This routine should not be called by a driver after its disconnect method has returned.

COPYRIGHT

Kernel Hackers Manual 3.10					     June 2014							 USB_POISON_URB(9)