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

NAME

       rmvq - remove a message from a queue

SYNOPSIS

       #include <sys/stream.h>

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

INTERFACE LEVEL

       Architecture independent level 1 (DDI/DKI).

PARAMETERS

       q	Queue containing the message to be removed.

       mp	Message to remove.

DESCRIPTION

       rmvq()  removes	a  message  from a queue. A message can be removed from anywhere on a queue. To prevent modules and drivers from having to
       deal with the internals of message linkage on a queue, either rmvq() or getq(9F) should be used to remove a message from a queue.

CONTEXT

       rmvq() can be called from user or interrupt context.

EXAMPLES

       This code fragment illustrates how one may flush one type of message from a queue. In this  case,  only	M_PROTO  T_DATA_IND  messages  are
       flushed.  For each message on the queue, if it is an M_PROTO message (line 8) of type T_DATA_IND (line 10), save a pointer to the next mes-
       sage (line 11), remove the T_DATA_IND message (line 12) and free it (line 13). Continue with the next message in the list (line 19).

	1  mblk_t *mp, *nmp;
	2  queue_t *q;
	3  union T_primitives *tp;
	4
	5   /* Insert code here to protect queue and message block */
	6   mp = q->q_first;
	7   while (mp) {
	8	 if (mp->b_datap->db_type == M_PROTO) {
	9	      tp = (union T_primitives *)mp->b_rptr;
       10	      if (tp->type == T_DATA_IND) {
       11		   nmp = mp->b_next;
       12		   rmvq(q, mp);
       13		   freemsg(mp);
       14		   mp = nmp;
       15	      } else {
       16		   mp = mp->b_next;
       17	      }
       18	 } else {
       19	      mp = mp->b_next;
       20	 }
       21   }
       22   /* End of region that must be protected */

       When using rmvq(), you must ensure that the queue and the message block is not modified by another thread at the same time. You can achieve
       this either by using STREAMS functions or by implementing your own locking.

SEE ALSO

       freemsg(9F), getq(9F), insq(9F)

       Writing Device Drivers

       STREAMS Programming Guide

WARNINGS

       Make sure that the message mp is linked onto q to avoid a possible system panic.

SunOS 5.10							    9 Jul 2001								  rmvq(9F)