freezestr(9f) [sunos man page]

freezestr(9F)						   Kernel Functions for Drivers 					     freezestr(9F)

NAME

       freezestr, unfreezestr - freeze, thaw the state of a stream

SYNOPSIS

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

       void freezestr(queue_t *q);

       void unfreezestr(queue_t *q);

INTERFACE LEVEL

       Architecture independent level 1 (DDI/DKI).

PARAMETERS

       q	Pointer to the message queue to freeze/unfreeze.

DESCRIPTION

       freezestr()  freezes  the state of the entire stream containing the queue pair q. A frozen stream blocks any thread attempting to enter any
       open, close, put or service routine belonging to any queue instance in the stream, and blocks any thread currently within the stream if	it
       attempts  to put messages onto or take messages off of any queue within the stream (with the sole exception of the caller). Threads blocked
       by this mechanism remain so until the stream is thawed by a call to unfreezestr().

       Drivers and modules must freeze the stream before manipulating the queues directly (as opposed to manipulating  them  through  programmatic
       interfaces such as getq(9F), putq(9F), putbq(9F), etc.)

CONTEXT

       These routines may be called from any stream open, close, put or service routine as well as interrupt handlers, callouts and call-backs.

SEE ALSO

       Writing Device Drivers

       STREAMS Programming Guide

NOTES

       The  freezestr()  and  unfreezestr()  functions	can have a serious impact on system performance. Their use should be very limited. In most
       cases, there is no need to use freezestr() and there are usually better ways to accomplish what you need to do than by freezing the stream.

       Calling freezestr() to freeze a stream that is already frozen by the caller will result in a single-party deadlock.

       The caller of unfreezestr() must be the thread who called freezestr().

       STREAMS utility functions such as getq(9F), putq(9F), putbq(9F), and so forth, should not be called by the caller of freezestr() while  the
       stream is still frozen, as they indirectly freeze the stream to ensure atomicity of queue manipulation.

SunOS 5.10							    17 Oct 2000 						     freezestr(9F)

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put(9F) 						   Kernel Functions for Drivers 						   put(9F)

NAME

       put - call a STREAMS put procedure

SYNOPSIS

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

       void put(queue_t *q, mblk_t *mp);

INTERFACE LEVEL

       Architecture independent level 1 (DDI/DKI).

PARAMETERS

       q      Pointer to a STREAMS queue.

       mp     Pointer to message block being passed into queue.

DESCRIPTION

       put()  calls the put procedure ( put(9E) entry point) for the STREAMS queue specified by q, passing it the message block referred to by mp.
       It is typically used by a driver or module to call its own put procedure.

CONTEXT

       put() can be called from a STREAMS module or driver put or service routine, or from an associated interrupt handler, timeout,  bufcall,	or
       esballoc call-back. In the latter cases, the calling code must guarantee the validity of the q argument.

       Since  put()  may cause re-entry of the module (as it is intended to do), mutexes or other locks should not be held across calls to it, due
       to the risk of single-party deadlock (put(9E), putnext(9F), putctl(9F), qreply(9F)). This function is  provided	as  a  DDI/DKI	conforming
       replacement for a direct call to a put procedure.

SEE ALSO

       put(9E), freezestr(9F), putctl(9F), putctl1(9F), putnext(9F), putnextctl(9F), putnextctl1(9F), qprocson(9F), qreply(9F)

       Writing Device Drivers

	STREAMS Programming Guide

NOTES

       The caller cannot have the stream frozen when calling this function. See  freezestr(9F).

       DDI/DKI	conforming  modules  and  drivers  are	no longer permitted to call put procedures directly, but must call through the appropriate
       STREAMS utility function, for example, put(9E), putnext(9F), putctl(9F), and qreply(9F). This function is provided as a DDI/DKI	conforming
       replacement for a direct call to a put procedure.

       The put() and putnext() functions should be called only after qprocson() is finished.

SunOS 5.11							    28 Apr 1992 							   put(9F)

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freezestr(9f) [sunos man page]

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