NAME

qbufcall − call a function when a buffer becomes available

SYNOPSIS

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

int qbufcall(queue_t ∗q, uint size, int pri, void (∗func)(long arg), long arg );

INTERFACE LEVEL

Solaris DDI specific (Solaris DDI). 

ARGUMENTS

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 5.5.1  —  Last change: 10 Jan 1993