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Name

Synopsis

mblk_t *esballoc(unsigned char *base, int size, int pri, frtn_t *fr_rtnp);

Interface Level

Architecture independent level 1 (DDI/DKI).

Arguments

base

Address of user supplied data buffer.

size

Number of bytes in data buffer.

pri

Priority of allocation request (to be used by allocb(9F) function, called by esballoc()).

fr_rtnp

Free routine data structure.

Description

When freeb(9F) is called to free the message, the driver’s message freeing routine (referenced through the free_rtn structure) is called, with appropriate arguments, to free the data buffer.

The free_rtn structure includes the following members:

void (*free_func)();    /* user’s freeing routine */
char *free_arg;    /* arguments to free_func() */

Instead of requiring a specific number of arguments, the free_arg field is defined of type char *. This way, the driver can pass a pointer to a structure if more than one argument is needed.

The method by which free_func is called is implementation-specific. The module writer must not assume that free_func will or will not be called directly from STREAMS utility routines like freeb(9F) which free a message block.

free_func must not call another modules put procedure nor attempt to acquire a private module lock which may be held by another thread across a call to a STREAMS utility routine which could free a message block. Otherwise, the possibility for lock recursion and/or deadlock exists.

free_func must not access any dynamically allocated data structure that might no longer exist when it runs.

Return Values

Context

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

See Also

Warnings

The free_func must be defined in kernel space, should be declared void and accept one argument. It has no user context and must not sleep.

Table of Contents

• Name
• Synopsis
• Interface Level
• Arguments
• Description
• Return Values
• Context
• See Also
• Warnings