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putnextctl(9f) [bsd man page]

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

NAME
putnextctl - send a control message to a queue SYNOPSIS
#include <sys/stream.h> int putnextctl(queue_t *q, int type); INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI). PARAMETERS
q Queue to which the message is to be sent. type Message type (must be control, not data type). DESCRIPTION
putnextctl() tests the type argument to make sure a data type has not been specified, and then attempts to allocate a message block. put- nextctl() fails if type is M_DATA, M_PROTO, or M_PCPROTO, or if a message block cannot be allocated. If successful, putnextctl() calls the put(9E) routine of the queue pointed to by q with the newly allocated and initialized messages. A call to putnextctl(q,type) is an atomic equivalent of putctl(q->q_next,type). The STREAMS framework provides whatever mutual exclusion is necessary to insure that dereferencing q through its q_next field and then invoking putctl(9F) proceeds without interference from other threads. putnextctl() should always be used in preference to putctl(9F) RETURN VALUES
On success, 1 is returned. If type is a data type, or if a message block cannot be allocated, 0 is returned. CONTEXT
putnextctl() can be called from user or interrupt context. EXAMPLES
The send_ctl routine is used to pass control messages downstream. M_BREAK messages are handled with putnextctl() (line 8). put- nextctl1(9F) (line 13) is used for M_DELAY messages, so that parm can be used to specify the length of the delay. In either case, if a message block cannot be allocated a variable record- ing the number of allocation failures is incremented (lines 9, 14). If an invalid message type is detected, cmn_err(9F) panics the sys- tem (line 18). 1 void 2 send_ctl(queue_t *wrq, uchar_t type, uchar_t parm) 3 { 4 extern int num_alloc_fail; 5 6 switch (type) { 7 case M_BREAK: 8 if (!putnextctl(wrq, M_BREAK)) 9 num_alloc_fail++; 10 break; 11 12 case M_DELAY: 13 if (!putnextctl1(wrq, M_DELAY, parm)) 14 num_alloc_fail++; 15 break; 16 17 default: 18 cmn_err(CE_PANIC, "send_ctl: bad message type passed"); 19 break; 20 } 21 } SEE ALSO
put(9E), cmn_err(9F), datamsg(9F), putctl(9F), putnextctl1(9F) Writing Device Drivers STREAMS Programming Guide SunOS 5.10 29 Mar 1993 putnextctl(9F)

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

NAME
putnextctl - send a control message to a queue SYNOPSIS
#include <sys/stream.h> int putnextctl(queue_t *q, int type); INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI). PARAMETERS
q Queue to which the message is to be sent. type Message type (must be control, not data type). DESCRIPTION
putnextctl() tests the type argument to make sure a data type has not been specified, and then attempts to allocate a message block. put- nextctl() fails if type is M_DATA, M_PROTO, or M_PCPROTO, or if a message block cannot be allocated. If successful, putnextctl() calls the put(9E) routine of the queue pointed to by q with the newly allocated and initialized messages. A call to putnextctl(q,type) is an atomic equivalent of putctl(q->q_next,type). The STREAMS framework provides whatever mutual exclusion is necessary to insure that dereferencing q through its q_next field and then invoking putctl(9F) proceeds without interference from other threads. putnextctl() should always be used in preference to putctl(9F) RETURN VALUES
On success, 1 is returned. If type is a data type, or if a message block cannot be allocated, 0 is returned. CONTEXT
putnextctl() can be called from user or interrupt context. EXAMPLES
The send_ctl routine is used to pass control messages downstream. M_BREAK messages are handled with putnextctl() (line 8). put- nextctl1(9F) (line 13) is used for M_DELAY messages, so that parm can be used to specify the length of the delay. In either case, if a message block cannot be allocated a variable record- ing the number of allocation failures is incremented (lines 9, 14). If an invalid message type is detected, cmn_err(9F) panics the sys- tem (line 18). 1 void 2 send_ctl(queue_t *wrq, uchar_t type, uchar_t parm) 3 { 4 extern int num_alloc_fail; 5 6 switch (type) { 7 case M_BREAK: 8 if (!putnextctl(wrq, M_BREAK)) 9 num_alloc_fail++; 10 break; 11 12 case M_DELAY: 13 if (!putnextctl1(wrq, M_DELAY, parm)) 14 num_alloc_fail++; 15 break; 16 17 default: 18 cmn_err(CE_PANIC, "send_ctl: bad message type passed"); 19 break; 20 } 21 } SEE ALSO
put(9E), cmn_err(9F), datamsg(9F), putctl(9F), putnextctl1(9F) Writing Device Drivers STREAMS Programming Guide SunOS 5.10 29 Mar 1993 putnextctl(9F)

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