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

qtimeout - execute a function after a specified length of time

#include <sys/stream.h>
#include <sys/ddi.h>
timeout_id_t qtimeout(queue_t *q, void (*func)(void *),
     void *arg, clock_t ticks);

illumos DDI specific (illumos DDI).

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.

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().

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.

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

drv_usectohz(9F), mt-streams(9F), qbufcall(9F), qprocson(9F), qunbufcall(9F), quntimeout(9F)

Writing Device Drivers

STREAMS Programming Guide

January 16, 2006 OmniOS