STREAMS-UX Programmer's Guide (February 2007)

STREAMS Utilities Supported by HP-UX

Appendix B

193

NAME

putbq () – Places a message back at the head of a queue.

SYNOPSIS

#include <sys/stream.h>

int putbq (queue_t *q, mblk_t *mp);

PARAMETERS

Pointer to the queue.

Pointer to the message.

DESCRIPTION

This function places the specified message at its assigned priority as close to the head of the queue as

possible. It is normally called by the service procedure for the queue, and is invoked when a canput() or

bcanput() call from the service procedure detects a flow control condition. All flow control parameters for the

queue are updated. Note that high priority messages should not be placed back on a queue. They should be

processed in spite of flow control.

RETURN VALUES

putbq() returns a 1 on success and a 0 on failure.

CONSTRAINTS

putbq() can be called from thread or interrupt context. Only spinlocks of STREAMS/UX user lock order can

be held across this call.