Tribblix: manual page: qtimeout.9f

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

NAME

qtimeout - execute a function after a specified length of time

SYNOPSIS

#include <sys/stream.h>
#include <sys/ddi.h>

timeout_id_t qtimeout(queue_t *q, void (*func)(void *),
void *arg, clock_t ticks);

INTERFACE LEVEL

illumos DDI specific (illumos DDI).

PARAMETERS

q
Pointer to STREAMS queue structure.

func
Kernel function to invoke when the time increment expires.

arg
Argument to the function.

ticks
Number of clock ticks to wait before the function is called.
Use drv_usectohz(9F) to convert microseconds to clock ticks.

DESCRIPTION

The qtimeout() function schedules the specified function func to be
called after a specified time interval. func is called with arg as a
parameter. Control is immediately returned to the caller. This is
useful when an event is known to occur within a specific time frame,
or when you want to wait for I/O processes when an interrupt is not
available or might cause problems. The exact time interval over which
the timeout takes effect cannot be guaranteed, but the value given is
a close approximation.

The qtimeout() function is tailored to be used with the enhanced
STREAMS framework interface which is based on the concept of
perimeters. (See mt-streams(9F).) qtimeout() schedules the specified
function to execute after entering the perimeters associated with the
queue passed in as the first parameter to qtimeout(). All outstanding
timeouts and bufcalls must be cancelled (using, respectively,
quntimeout(9F) and qunbufcall(9F)) before a driver close routine can
block and before the close routine calls qprocsoff(9F).

The qprocson(9F) function must be called before calling qtimeout().

RETURN VALUES

The qtimeout() function returns an opaque non-zero timeout identifier
that can be passed to quntimeout(9F) to cancel the request. Note: No
value is returned from the called function.

CONTEXT

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