xref: /titanic_52/usr/src/man/man9f/WR.9f (revision 69a119caa6570c7077699161b7c28b6ee9f8b0f4)
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Copyright 1989 AT&T
Copyright (c) 2006, Sun Microsystems, Inc., All Rights Reserved
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When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
WR 9F "Jan 16, 2006"
NAME
WR, wr - get pointer to the write queue for this module or driver
SYNOPSIS

#include <sys/stream.h>
#include <sys/ddi.h>



queue_t *WR(queue_t *q);
INTERFACE LEVEL

Architecture independent level 1 (DDI/DKI).

PARAMETERS
q

Pointer to the read queue whose write queue is to be returned.

DESCRIPTION

The WR() function accepts a read queue pointer as an argument and returns a pointer to the write queue of the same module.

CAUTION: Make sure the argument to this function is a pointer to a read queue. WR() will not check for queue type, and a system panic could result if the pointer is not to a read queue.

RETURN VALUES

The pointer to the write queue.

CONTEXT

The WR() function can be called from user, interrupt, or kernel context.

EXAMPLES

Example 1 Using WR()

In a STREAMS close(9E) routine, the driver or module is passed a pointer to the read queue. These usually are set to the address of the module-specific data structure for the minor device.


1 xxxclose(q, flag)
2 queue_t *q;
3 int flag;
4 {
5 q->q_ptr = NULL;
6 WR(q)->q_ptr = NULL;
 . . .
7 }
SEE ALSO

close(9E), OTHERQ(9F), RD(9F)

Writing Device Drivers

STREAMS Programming Guide