opensolaris man page for qbufcall

qbufcall(9F)						   Kernel Functions for Drivers 					      qbufcall(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
       The  qbufcall()	function  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 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).

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

RETURN VALUES
       If successful, the qbufcall() function 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
       The qbufcall() function can be called from user, interrupt, or kernel 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 5.11							    16 Jan 2006 						      qbufcall(9F)