qtimeout(9f)

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

6       qtimeout - execute a function after a specified length of time
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SYNOPSIS

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

18       Solaris DDI specific (Solaris DDI).
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PARAMETERS

21       q        Pointer to STREAMS queue structure.
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24       func     Kernel function to invoke when the time increment expires.
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27       arg      Argument to the function.
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30       ticks    Number  of  clock ticks to wait before the function is called.
31                Use drv_usectohz(9F) to convert microseconds to clock ticks.
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DESCRIPTION

35       The qtimeout() function schedules the specified  function  func  to  be
36       called  after  a  specified time interval. func is called with arg as a
37       parameter. Control is immediately returned to the caller. This is  use‐
38       ful  when  an  event is known to occur within a specific time frame, or
39       when you want to wait for I/O processes when an interrupt is not avail‐
40       able  or  might  cause problems. The exact time interval over which the
41       timeout takes effect cannot be guaranteed, but the  value  given  is  a
42       close approximation.
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45       The  qtimeout()  function  is  tailored  to  be  used with the enhanced
46       STREAMS framework interface which is based on the  concept  of  perime‐
47       ters. (See mt-streams(9F).) qtimeout() schedules the specified function
48       to execute after entering the  perimeters  associated  with  the  queue
49       passed  in  as the first parameter to qtimeout(). All outstanding time‐
50       outs and bufcalls must  be  cancelled  (using,  respectively,  quntime‐
51       out(9F) and qunbufcall(9F)) before a driver close routine can block and
52       before the close  routine calls qprocsoff(9F).
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55       The qprocson(9F) function must be called before calling qtimeout().
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RETURN VALUES

58       The qtimeout() function returns an opaque non-zero  timeout  identifier
59       that  can  be  passed to quntimeout(9F) to cancel the request. Note: No
60       value is returned from the called function.
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CONTEXT

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