wr(9F) (man pages section 9F: DDI and DKI Kernel Functions)

man pages section 9F: DDI and DKI Kernel Functions

wr(9F)

NAME

WR, wr- get pointer to the write queue for this module or driver

SYNOPSIS

#include <sys/stream.h>
#include <sys/ddi.h>

q

INTERFACE LEVEL

Architecture independent level 1 (DDI/DKI).

PARAMETERS

q: Pointer to the read queue whose write queue is to be returned.

DESCRIPTION

The WR() function accepts a read queue pointer as an argument and returns a pointer to the write queue of the same module.

CAUTION: Make sure the argument to this function is a pointer to a read queue. WR() will not check for queue type, and a system panic could result if the pointer is not to a read queue.

RETURN VALUES

The pointer to the write queue.

CONTEXT

WR() can be called from user or interrupt context.

EXAMPLES

Example 1 Using `WR()`

In a STREAMS close(9E) routine, the driver or module is passed a pointer to the read queue. These usually are set to the address of the module-specific data structure for the minor device.

 
1   xxxclose(q, flag)
2       queue_t *q;
3       int flag;
4   {
5	         q->q_ptr = NULL;
6         WR(q)->q_ptr = NULL;
	         . . .
7   }