opensolaris man page for freeb

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
       The freeb() function 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
       The freeb() function can be called from user, interrupt, or kernel 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 5.11							    16 Jan 2006 							 freeb(9F)