NAME | SYNOPSIS | INTERFACE LEVEL | PARAMETERS | DESCRIPTION | RETURN VALUES | CONTEXT | EXAMPLES | SEE ALSO | WARNINGS | NOTES
#include <sys/stream.h>int insq(queue_t *q, mblk_t *emp, mblk_t *nmp);
Architecture independent level 1 (DDI/DKI).
Pointer to the queue containing message emp.
Enqueued message before which the new message is to be inserted. mblk_t is an instance of the msgb(9S) structure.
Message to be inserted.
insq() inserts a message into a queue. The message to be inserted, nmp, is placed in q immediately before the message emp. If emp is NULL, the new message is placed at the end of the queue. The queue class of the new message is ignored. All flow control parameters are updated. The service procedure is enabled unless QNOENB is set.
insq() returns 1 on success, and 0 on failure.
insq() can be called from user or interrupt context.
This routine illustrates the steps a transport provider may take to place expedited data ahead of normal data on a queue (assume all M_DATA messages are converted into M_PROTO T_DATA_REQ messages). Normal T_DATA_REQ messages are just placed on the end of the queue (line 16). However, expedited T_EXDATA_REQ messages are inserted before any normal messages already on the queue (line 25). If there are no normal messages on the queue, bp will be NULL and we fall out of the for loop (line 21). insq acts like putq(9F) in this case.
1 #include 2 #include 3 4 static int 5 xxxwput(queue_t *q, mblk_t *mp) 6 { 7 union T_primitives *tp; 8 mblk_t *bp; 9 union T_primitives *ntp; 10 11 switch (mp->b_datap->db_type) { 12 case M_PROTO: 13 tp = (union T_primitives *)mp->b_rptr; 14 switch (tp->type) { 15 case T_DATA_REQ: 16 putq(q, mp); 17 break; 18 19 case T_EXDATA_REQ: 20 freezestr(q); 21 for (bp = q->q_first; bp; bp = bp->b_next) { 22 if (bp->b_datap->db_type == M_PROTO) { 23 ntp = (union T_primitives *)bp->b_rptr; 24 if (ntp->type != T_EXDATA_REQ) 25 break; 26 } 27 } 28 (void)insq(q, bp, mp); 29 unfreezestr(q); 30 break; . . . 31 } 32 } 33 }
If emp is non-NULL, it must point to a message on q or a system panic could result.
The stream must be frozen using freezestr(9F) before calling insq().
NAME | SYNOPSIS | INTERFACE LEVEL | PARAMETERS | DESCRIPTION | RETURN VALUES | CONTEXT | EXAMPLES | SEE ALSO | WARNINGS | NOTES