canputnext(9F) Kernel Functions for Drivers canputnext(9F)
NAME
canputnext, bcanputnext - test for room in next module's message queue
SYNOPSIS
#include <sys/stream.h>
int canputnext(queue_t *q);
int bcanputnext(queue_t *q, unsigned char pri);
INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI).
PARAMETERS
q Pointer to a message queue belonging to the invoking module.
pri Minimum priority level.
DESCRIPTION
The invocation canputnext(q); is an atomic equivalent of the canput(q->q_next); routine. That is, the STREAMS framework provides whatever
mutual exclusion is necessary to insure that dereferencing q through its q_next field and then invoking canput(9F) proceeds without inter-
ference from other threads.
bcanputnext(q, pri); is the equivalent of the bcanput(q->q_next, pri); routine.
canputnext(q); and bcanputnext(q, pri); should always be used in preference to canput(q->q_next); and bcanput(q->q_next, pri); respec-
tively.
See canput(9F) and bcanput(9F) for further details.
RETURN VALUES
1 If the message queue is not full.
0 If the queue is full.
CONTEXT
canputnext() and bcanputnext() can be called from user or interrupt context.
WARNINGS
Drivers are responsible for both testing a queue with canputnext() or bcanputnext() and refraining from placing a message on the queue if
the queue is full.
SEE ALSO
bcanput(9F), canput(9F)
Writing Device Drivers
STREAMS Programming Guide
SunOS 5.10 31 Jan 1993 canputnext(9F)
