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.\" -*- nroff -*-
.\"
.\" copyright (C) 1997 Stephen Williams <steve@icarus.com>
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date. The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein. The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.TH MOD_INC_USE_COUNT 9 "$Date:$" "Linux DDI" "Kernel Functions"
.SH NAME
MOD_INC_USE_COUNT, MOD_DEC_USE_COUNT \- Support reference counting of modules
.SH SYNOPSIS
.B #include <linux/module.h>
.sp
.B #define MOD_INC_USE_COUNT
.br
.B #define MOD_DEC_USE_COUNT
.SH DESCRIPTION
These macros support reference counting of modules during their
lifetime. Each time
.BR MOD_INC_USE_COUNT "(9)"
is invoked, the kernel increases the number of counted references to
the module. The
.BR MOD_DEC_USE_COUNT "(9)"
decreases the reference count.
.PP
The reference count is used by the kernel to know when a module is no
longer in use by the device or application software. A
.BR MOD_INC_USE_COUNT "(9)"
is generally placed in the open entry for a driver, and a
.BR MOD_DEC_USE_COUNT "(9)"
in the release for the driver,
to count the number of times the device has been opened, and thus
prevent the module being unloaded when in use. The device driver may
increment the use count other times, such as when memory is mapped or
the module must remain loaded for external events.
.PP
If the device driver is not compiled as a module
.IR "" ( MODULE
is not defined) then the macro reduces to no behavior.
.SH "RETURN VALUE"
These macros take no parameters and return no result.
.SH AVAILABILITY
Linux 1.0+
.SH "SEE ALSO"
.I "/usr/include/linux/module.h"
.SH AUTHOR
Stephen Williams <steve@icarus.com>
.SH BUGS
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