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Kernel Functions for Drivers

backq(9F)

INTERFACE LEVEL
PARAMETERS
DESCRIPTION
RETURN VALUES
CONTEXT
SEE ALSO

NAME

backq - 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.

backq() 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

backq() can be called from user or interrupt context.