flushq(9F) manual page
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flushq - remove messages from a queue
#include <sys/stream.h>
void flushq(queue_t *q, int flag);
Architecture independent
level 1 (DDI/DKI).
- q
- Pointer to the queue to be flushed.
- flag
- Valid
flag values are:
- FLUSHDATA
- Flush only data messages (types M_DATA
M_DELAY
M_PROTO
and M_PCPROTO
).
- FLUSHALL
- Flush all messages.
flushq()
frees messages and their associated data structures by calling freemsg(9F)
.
If the queue’s count falls below the low water mark and the queue was blocking
an upstream service procedure, the nearest upstream service procedure is
enabled.
flushq() can be called from user or interrupt context.
This
example depicts the canonical flushing code for STREAMS modules. The module
has a write service procedure and potentially has messages on the queue.
If it receives an M_FLUSH
message, and if the FLUSHR
bit is on in
the first byte of the message (line 10), then the read queue is flushed
(line 11). If the FLUSHW
bit is on (line 12), then the write queue is
flushed (line 13). Then the message is passed along to the next entity in
the stream (line 14). See the example for qreply(9F)
for the canonical
flushing code for drivers.
1 /*
2 * Module write-side put procedure.
3 */
4 xxxwput(q, mp)
5 queue_t *q;
6 mblk_t *mp;
7 {
8 switch(mp->b_datap->db_type) {
9 case M_FLUSH:
10 if (*mp->b_rptr & FLUSHR)
11 flushq(RD(q), FLUSHALL);
12 if (*mp->b_rptr & FLUSHW)
13 flushq(q, FLUSHALL);
14 putnext(q, mp);
15 break;
. . .
16 }
17 }
flushband(9F)
, freemsg(9F)
, putq(9F)
, qreply(9F)
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