unlinkb(9f) [opensolaris man page]

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

NAME

       unlinkb - remove a message block from the head of a message

SYNOPSIS

       #include <sys/stream.h>

       mblk_t *unlinkb(mblk_t *mp);

INTERFACE LEVEL

       Architecture independent level 1 (DDI/DKI).

PARAMETERS

       mp    Pointer to the message.

DESCRIPTION

       The  unlinkb()  function removes the first message block from the message pointed to by mp. A new message, minus the removed message block,
       is returned.

RETURN VALUES

       If successful, the unlinkb() function returns a pointer to the message with the first message block removed. If there is only  one  message
       block in the message, NULL is returned.

CONTEXT

       The unlinkb() function can be called from user, interrupt, or kernel context.

EXAMPLES

       Example 1 unlinkb() example

       The  routine  expects  to  get  passed  an M_PROTO T_DATA_IND message. It will remove and free the  M_PROTO header and return the remaining
       M_DATA portion of the message.

	 1  mblk_t *
	 2  makedata(mp)
	 3	mblk_t *mp;
	 4  {
	 5    mblk_t *nmp;
	 6
	 7    nmp = unlinkb(mp);
	 8    freeb(mp);
	 9    return(nmp);
	 10 }

SEE ALSO

       linkb(9F)

       Writing Device Drivers

       STREAMS Programming Guide

SunOS 5.11							    16 Jan 2006 						       unlinkb(9F)

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

       The  rmvq() function 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

       The rmvq() function can be called from user, interrupt, or kernel 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 5.11							    16 Jan 2006 							  rmvq(9F)