Kernel Functions for Drivers                            freeb(9F)



NAME
     freeb - free a message block

SYNOPSIS
     #include 



     void freeb(mblkt *bp);


PARAMETERS
     bp    Pointer to the message block to be deallocated. mblkt
           is an instance of the msgb(9S) structure.


INTERFACE LEVEL
     Architecture independent level 1 (DI/DKI).

DESCRIPTION
     The freeb() function deallocates a  message  block.  If  the
     reference count of the dbref member of the datab(9S) struc-
     ture is greater than 1, freeb()  decrements  the  count.  If
     dbref  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 rou-
     tine. To make this process independent of the driver used in
     the stream, freeb() finds the freertn(9S) structure associ-
     ated with the buffer.  The  freertn  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), freertn(9S)




SunOS 5.11          Last change: 16 Jan 2006                    1






Kernel Functions for Drivers                            freeb(9F)



     Writing Device Drivers


     STREAMS Programming Guide



















































SunOS 5.11          Last change: 16 Jan 2006                    2