putctl(D3) putctl(D3)
NAME
putctl - send a control message to a queue
SYNOPSIS
#include <sys/stream.h>
#include <sys/ddi.h>
int putctl(queue_t *q, int type);
Arguments
q Pointer to the queue to which the message is to be
sent.
type Message type (must be a control type).
DESCRIPTION
putctl tests the type argument to make sure a data type has
not been specified, and then attempts to allocate a message
block. putctl fails if type is M_DATA, M_PROTO, or M_PCPROTO,
or if a message block cannot be allocated. If successful,
putctl calls the put(D2) routine of the queue pointed to by q,
passing it the allocated message.
Return Values
On success, 1 is returned. Otherwise, if type is a data type,
or if a message block cannot be allocated, 0 is returned.
USAGE
In multithreaded drivers, the q argument may not reference
q_next (for example, an argument of q->q_next is erroneous in
a multithreaded driver and is disallowed by the DDI/DKI).
putnextctl(q, type) is provided as a multiprocessor-safe
equivalent to the common call putctl(q->q_next, type), which
is no longer allowed.
Level
Base or Interrupt.
Synchronization Constraints
Does not sleep.
Driver-defined basic locks, read/write locks, and sleep locks
may not be held across calls to this function.
The caller cannot have the stream frozen [see freezestr(D3)]
when calling this function.
Copyright 1994 Novell, Inc. Page 1
putctl(D3) putctl(D3)
Examples
The send_ctl routine is used to pass control messages
downstream. M_BREAK messages are handled with putctl (line
9). putctl1 (line 11) is used for M_DELAY messages, so that
param can be used to specify the length of the delay. If an
invalid message type is detected, send_ctl returns 0,
indicating failure (line 13).
1 int
2 send_ctl(wrq, type, param)
3 queue_t *wrq;
4 uchar_t type;
5 uchar_t param;
6 {
7 switch (type) {
8 case M_BREAK:
9 return(putctl(wrq->q_next, M_BREAK));
10 case M_DELAY:
11 return(putctl1(wrq->q_next, M_DELAY, param));
12 default:
13 return(0);
14 }
15 }
REFERENCES
put(D2), put(D3), putctl1(D3), putnextctl(D3), putnextctl1(D3)
NOTICES
Portability
All processors
Applicability
ddi: 1, 2, 3, 4, 5, 5mp, 6, 6mp, 7, 7mp
Copyright 1994 Novell, Inc. Page 2