backq(9F) Kernel Functions for Drivers backq(9F)NAMEbackq - get pointer to the queue behind the current queue
SYNOPSIS
#include <sys/stream.h>
queue_t *backq(queue_t *cq);
INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI).
PARAMETERS
cq The pointer to the current queue. queue_t is an alias for the
queue(9S) structure.
DESCRIPTION
The backq() function returns a pointer to the queue preceding cq (the
current queue). If cq is a read queue, backq() returns a pointer to the
queue downstream from cq, unless it is the stream end. If cq is a write
queue, backq() returns a pointer to the next queue upstream from cq,
unless it is the stream head.
RETURN VALUES
If successful, backq() returns a pointer to the queue preceding the
current queue. Otherwise, it returns NULL.
CONTEXT
The backq() function can be called from user, interrupt, or kernel con‐
text.
SEE ALSOqueue(9S)
Writing Device Drivers
STREAMS Programming Guide
SunOS 5.11 16 Jan 2006 backq(9F)