queue(9s) [sunos man page]
queue(9S) Data Structures for Drivers queue(9S) NAME
queue - STREAMS queue structure SYNOPSIS
#include <sys/stream.h> INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI) DESCRIPTION
A STREAMS driver or module consists of two queue structures, one for upstream processing (read) and one for downstream processing (write). This structure is the major building block of a stream. It contains pointers to the processing procedures, pointers to the next and previous queues in the stream, flow control parameters, and a pointer defining the position of its messages on the STREAMS scheduler list. The queue structure is defined as type queue_t. STRUCTURE MEMBERS
struct qinit*q_qinfo; /* module or driver entry points */ struct msgb*q_first; /* first message in queue */ struct msgb*q_last; /* last message in queue */ struct queue*q_next; /* next queue in stream */ struct queue*q_link; /* to next queue for scheduling*/ void *q_ptr; /* pointer to private data structure */ size_t q_count; /* approximate size of message queue */ uint_t q_flag; /* status of queue */ ssize_t q_minpsz; /* smallest packet accepted by QUEUE*/ ssize_t q_maxpsz; /*largest packet accepted by QUEUE */ size_t q_hiwat; /* high water mark */ size_t q_lowat; /* low water mark */ Valid flags are as follows: QENAB Queue is already enabled to run. QWANTR Someone wants to read queue. QWANTW Someone wants to write to queue. QFULL Queue is considered full. QREADR This is the reader (first) queue. QUSE This queue is in use (allocation). QNOENB Do not enable queue by way of putq(). SEE ALSO
strqget(9F), strqset(9F), module_info(9S), msgb(9S), qinit(9S), streamtab(9S) Writing Device Drivers STREAMS Programming Guide SunOS 5.10 12 Nov 1996 queue(9S)
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flushq(9F) Kernel Functions for Drivers flushq(9F) NAME
flushq - remove messages from a queue SYNOPSIS
#include <sys/stream.h> void flushq(queue_t *q, int flag); INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI). PARAMETERS
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. DESCRIPTION
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. CONTEXT
flushq() can be called from user or interrupt context. EXAMPLES
Example 1: Using flushq() 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 } SEE ALSO
flushband(9F), freemsg(9F), putq(9F), qreply(9F) Writing Device Drivers STREAMS Programming Guide SunOS 5.10 11 Apr 1991 flushq(9F)