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  lifetime.  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    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>

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