illumos: manual page: putnextctl1.9f

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().