PUTNEXTCTL1(9F) Kernel Functions for Drivers PUTNEXTCTL1(9F)

NAME


putnextctl1 - send a control message with a one-byte parameter to a queue

SYNOPSIS


#include <sys/stream.h>


int putnextctl1(queue_t *q, int type, int p);


INTERFACE LEVEL


Architecture independent level 1 (DDI/DKI).

PARAMETERS


q
Queue to which the message is to be sent.


type
Type of message.


p
One-byte parameter.


DESCRIPTION


The putnextctl1() function, like putctl1(9F), tests the type argument to
make sure a data type has not been specified, and attempts to allocate a
message block. The p parameter can be used, for example, to specify how
long the delay will be when an M_DELAY message is being sent.
putnextctl1() fails if type is M_DATA, M_PROTO, or M_PCPROTO, or if a
message block cannot be allocated. If successful, putnextctl1() calls the
put(9E) routine of the queue pointed to by q with the newly allocated and
initialized message.


A call to putnextctl1(q,type, p) is an atomic equivalent of
putctl1(q->q_next, type, p). The STREAMS framework provides whatever
mutual exclusion is necessary to insure that dereferencing q through its
q_next field and then invoking putctl1(9F) proceeds without interference
from other threads.


The putnextctl1() function should always be used in preference to
putctl1(9F)

RETURN VALUES


On success, 1 is returned. 0 is returned if type is a data type, or if a
message block cannot be allocated.

CONTEXT


The putnextctl1() function can be called from user, interrupt, or kernel
context.

EXAMPLES


See the putnextctl(9F) function page for an example of putnextctl1().

SEE ALSO


put(9E), allocb(9F), datamsg(9F), putctl1(9F), putnextctl(9F)


Writing Device Drivers


STREAMS Programming Guide

illumos January 16, 2006 PUTNEXTCTL1(9F)