free_rtn(9S) Data Structures for Drivers free_rtn(9S)NAME
free_rtn - structure that specifies a driver's message-freeing routine
SYNOPSIS
#include <sys/stream.h>
INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI).
DESCRIPTION
The free_rtn structure is referenced by the datab structure. When freeb(9F) is called to free the message, the driver's message-freeing
routine (referenced through the free_rtn structure) is called, with arguments, to free the data buffer.
STRUCTURE MEMBERS
void (*free_func)() /* user's freeing routine */
char *free_arg /* arguments to free_func() */
The free_rtn structure is defined as type frtn_t.
SEE ALSO esballoc(9F), freeb(9F), datab(9S)
STREAMS Programming Guide
SunOS 5.10 13 Nov 1996 free_rtn(9S)
Check Out this Related Man Page
freeb(9F) Kernel Functions for Drivers freeb(9F)NAME
freeb - free a message block
SYNOPSIS
#include <sys/stream.h>
void freeb(mblk_t *bp);
PARAMETERS
bp Pointer to the message block to be deallocated. mblk_t is an instance of the msgb(9S) structure.
INTERFACE LEVEL
Architecture independent level 1 (DDI/DKI).
DESCRIPTION
freeb() deallocates a message block. If the reference count of the db_ref member of the datab(9S) structure is greater than 1, freeb()
decrements the count. If db_ref equals 1, it deallocates the message block and the corresponding data block and buffer.
If the data buffer to be freed was allocated with the esballoc(9F), the buffer may be a non-STREAMS resource. In that case, the driver
must be notified that the attached data buffer needs to be freed, and run its own freeing routine. To make this process independent of the
driver used in the stream, freeb() finds the free_rtn(9S) structure associated with the buffer. The free_rtn structure contains a pointer
to the driver-dependent routine, which releases the buffer. Once this is accomplished, freeb() releases the STREAMS resources associated
with the buffer.
CONTEXT
freeb() can be called from user or interrupt context.
EXAMPLES
Example 1: Using freeb()
See copyb(9F) for an example of using freeb().
SEE ALSO allocb(9F), copyb(9F), dupb(9F), esballoc(9F), free_rtn(9S)
Writing Device Drivers
STREAMS Programming Guide
SunOS 5.10 13 Nov 2000 freeb(9F)
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