1qbufcall(9F)             Kernel Functions for Drivers             qbufcall(9F)
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NAME

6       qbufcall - call a function when a buffer becomes available
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SYNOPSIS

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

19       Solaris DDI specific (Solaris DDI).
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PARAMETERS

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

40       The  qbufcall() function serves as a qtimeout(9F) call of indeterminate
41       length. When a buffer allocation request fails, qbufcall() can be  used
42       to  schedule the routine func to be called with the argument arg when a
43       buffer becomes available. func may call allocb() or it may do something
44       else.
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47       The  qbufcall()  function  is  tailored  to  be  used with the enhanced
48       STREAMS framework interface, which is based on the concept  of  perime‐
49       ters. (See mt-streams(9F).) qbufcall() schedules the specified function
50       to execute after entering the  perimeters  associated  with  the  queue
51       passed  in  as the first parameter to qbufcall(). All outstanding time‐
52       outs and bufcalls must  be  cancelled  (using,  respectively,  quntime‐
53       out(9F) and qunbufcall(9F)) before a driver close routine can block and
54       before the close  routine calls qprocsoff(9F).
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57       qprocson(9F) must be called before calling either qbufcall() or  qtime‐
58       out(9F).
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RETURN VALUES

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

66       The  qbufcall()  function can be called from user, interrupt, or kernel
67       context.
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SEE ALSO

70       allocb(9F), mt-streams(9F), qprocson(9F), qtimeout(9F), qunbufcall(9F),
71       quntimeout(9F)
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74       Writing Device Drivers
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77       STREAMS Programming Guide
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WARNINGS

80       Even  when func is called by qbufcall(), allocb(9F) can fail if another
81       module or driver had allocated the memory before func was able to  call
82       allocb(9F).
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86SunOS 5.11                        16 Jan 2006                     qbufcall(9F)