Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
Copyright 1989 AT&T
The contents of this file are subject to the terms of the Common Development and Distribution License (the "License"). You may not use this file except in compliance with the License.
You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing. See the License for the specific language governing permissions and limitations under the License.
When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE. If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
#include <sys/stream.h> void freeb(mblk_t *bp);
bp
Pointer to the message block to be deallocated. mblk_t is an instance of the msgb(9S) structure.
Architecture independent level 1 (DDI/DKI).
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.
The freeb() function can be called from user, interrupt, or kernel context.
Example 1 Using freeb()
See copyb(9F) for an example of using freeb().
allocb(9F), copyb(9F), dupb(9F), esballoc(9F), free_rtn(9S)
Writing Device Drivers
STREAMS Programming Guide