getq(9F) Kernel Functions for Drivers getq(9F)NAMEgetq - get the next message from a queue
SYNOPSIS
#include <sys/stream.h>
mblk_t *getq(queue_t *q);
INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI).
PARAMETERS
q Pointer to the queue from which the message is to be retrieved.
DESCRIPTION
The getq() function is used by a service ( srv(9E)) routine to retrieve
its enqueued messages.
A module or driver may include a service routine to process enqueued
messages. Once the STREAMS scheduler calls srv() it must process all
enqueued messages, unless prevented by flow control. getq() obtains the
next available message from the top of the queue pointed to by q. It
should be called in a while loop that is exited only when there are no
more messages or flow control prevents further processing.
If an attempt was made to write to the queue while it was blocked by
flow control, getq() back-enables (restarts) the service routine once
it falls below the low water mark.
RETURN VALUES
If there is a message to retrieve, getq() returns a pointer to it. If
no message is queued, getq() returns a NULL pointer.
CONTEXT
The getq() function can be called from user, interrupt, or kernel con‐
text.
EXAMPLES
See dupb(9F).
SEE ALSOsrv(9E), bcanput(9F), canput(9F), dupb(9F), putbq(9F), putq(9F), qen‐
able(9F)
Writing Device Drivers
STREAMS Programming Guide
SunOS 5.11 16 Jan 2006 getq(9F)