MOD_INC_USE_COUNT(9) Kernel Functions MOD_INC_USE_COUNT(9)NAME
MOD_INC_USE_COUNT, MOD_DEC_USE_COUNT - Support reference counting of
modules
SYNOPSIS
#include <linux/module.h>
#define MOD_INC_USE_COUNT
#define MOD_DEC_USE_COUNT
DESCRIPTION
These macros support reference counting of modules during their life‐
time. Each time MOD_INC_USE_COUNT(9) is invoked, the kernel increases
the number of counted references to the module. The
MOD_DEC_USE_COUNT(9) decreases the reference count.
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
MOD_INC_USE_COUNT(9) is generally placed in the open entry for a
driver, and a 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.
If the device driver is not compiled as a module (MODULE is not
defined) then the macro reduces to no behavior.
RETURN VALUE
These macros take no parameters and return no result.
AVAILABILITY
Linux 1.0+
SEE ALSO
/usr/include/linux/module.h
AUTHOR
Stephen Williams <steve@icarus.com>
BUGSLinux DDI $Date:$ MOD_INC_USE_COUNT(9)