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.TH "USB_UNLINK_URB" "9" "09 April 2004" "" ""

.SH NAME
usb_unlink_urb \- abort/cancel a transfer request for an endpoint
.SH SYNOPSIS
.sp
\fB
.sp
int usb_unlink_urb  (struct urb * \fIurb\fB);
\fR
.SH "ARGUMENTS"
.TP
\fB\fIurb\fB\fR
pointer to urb describing a previously submitted request
.SH "DESCRIPTION"
.PP
This routine cancels an in-progress request.  URBs complete only
once per submission, and may be canceled only once per submission.
Successful cancelation means the requests's completion handler will
be called with a status code indicating that the request has been
canceled (rather than any other code) and will quickly be removed
from host controller data structures.
.PP
When the URB_ASYNC_UNLINK transfer flag for the URB is clear, this
request is synchronous.  Success is indicated by returning zero,
at which time the urb will have been unlinked and its completion
handler will have been called with urb->status -ENOENT.  Failure is
indicated by any other return value.
.PP
The synchronous cancelation mode may not be used
when unlinking an urb from an interrupt context, such as a bottom
half or a completion handler; or when holding a spinlock; or in
other cases when the caller can't \fBschedule\fR.
.PP
When the URB_ASYNC_UNLINK transfer flag for the URB is set, this
request is asynchronous.  Success is indicated by returning -EINPROGRESS,
at which time the urb will normally not have been unlinked.
The completion function will see urb->status -ECONNRESET.  Failure
is indicated by any other return value.
.SH "ABOUT THIS DOCUMENT"
.PP
This documentation was generated with kernel version 2.6.0.