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Kernel Functions for Driversqbufcall(9F)


NAME

 qbufcall - call a function when a buffer becomes available

SYNOPSIS

 
#include <sys/stream.h> 
#include <sys/ddi.h>
bufcall_id_t qbufcall(queue_t *q, size_t size, uint_t pri, void(*func)(void *arg), void *arg);

INTERFACE LEVEL

 

Solaris DDI specific (Solaris DDI).

PARAMETERS

 
q
Pointer to STREAMS queue structure.
size
Number of bytes required for the buffer.
pri
Priority of the allocb(9F) allocation request (not used).
func
Function or driver routine to be called when a buffer becomes available.
arg
Argument to the function to be called when a buffer becomes available.

DESCRIPTION

 

qbufcall() serves as a qtimeout(9F) call of indeterminate length. When a buffer allocation request fails, qbufcall() can be used to schedule the routine func to be called with the argument arg when a buffer becomes available. func may call allocb() or it may do something else.

The qbufcall() function is tailored to be used with the enhanced STREAMS framework interface, which is based on the concept of perimeters. (See mt-streams(9F).) qbufcall() schedules the specified function to execute after entering the perimeters associated with the queue passed in as the first parameter to qbufcall(). All outstanding bufcalls should be cancelled before the close of a driver or module returns.

qprocson(9F) must be called before calling either qbufcall() or qtimeout(9F).

RETURN VALUES

 

If successful, qbufcall() returns a qbufcall ID that can be used in a call to qunbufcall(9F) to cancel the request. If the qbufcall() scheduling fails, func is never called and 0 is returned.

CONTEXT

 

qbufcall() can be called from user or interrupt context.

SEE ALSO

 

allocb(9F), mt-streams(9F), qprocson(9F), qtimeout(9F), qunbufcall(9F), quntimeout(9F)

Writing Device Drivers

STREAMS Programming Guide

WARNINGS

 

Even when func is called by qbufcall(), allocb(9F) can fail if another module or driver had allocated the memory before func was able to call allocb(9F).


SunOS 5.9Go To TopLast Changed 18 Feb 1998

 
      
      
Copyright 2002 Sun Microsystems, Inc. All rights reserved. Use is subject to license terms.