include/linux/init.h

   1 #ifndef _LINUX_INIT_H
   2 #define _LINUX_INIT_H
   3
   4 /* These macros are used to mark some functions or
   5  * initialized data (doesn't apply to uninitialized data)
   6  * as `initialization' functions. The kernel can take this
   7  * as hint that the function is used only during the initialization
   8  * phase and free up used memory resources after
   9  *
  10  * Usage:
  11  * For functions:
  12  *
  13  * You should add __init immediately before the function name, like:
  14  *
  15  * static void __init initme(int x, int y)
  16  * {
  17  *    extern int z; z = x * y;
  18  * }
  19  *
  20  * Depricated: you can surround the whole function declaration
  21  * just before function body into __initfunc() macro, like:
  22  *
  23  * __initfunc (static void initme(int x, int y))
  24  * {
  25  *    extern int z; z = x * y;
  26  * }
  27  *
  28  * If the function has a prototype somewhere, you can also add
  29  * __init between closing brace of the prototype and semicolon:
  30  *
  31  * extern int initialize_foobar_device(int, int, int) __init;
  32  *
  33  * For initialized data:
  34  * You should insert __initdata between the variable name and equal
  35  * sign followed by value, e.g.:
  36  *
  37  * static int init_variable __initdata = 0;
  38  * static char linux_logo[] __initdata = { 0x32, 0x36, ... };
  39  *
  40  * For initialized data not at file scope, i.e. within a function,
  41  * you should use __initlocaldata instead, due to a bug in GCC 2.7.
  42  */
  43
  44 /*
  45  * Disable the __initfunc macros if a file that is a part of a
  46  * module attempts to use them. We do not want to interfere
  47  * with module linking.
  48  */
  49
  50 #ifndef MODULE
  51
  52 /*
  53  * Used for initialization calls..
  54  */
  55 typedef int (*initcall_t)(void);
  56
  57 extern initcall_t __initcall_start, __initcall_end;
  58
  59 #define __initcall(fn)                                                          \
  60         static initcall_t __initcall_##fn __init_call = fn
  61
  62 /*
  63  * Used for kernel command line parameter setup
  64  */
  65 struct kernel_param {
  66         const char *str;
  67         int (*setup_func)(char *);
  68 };
  69
  70 extern struct kernel_param __setup_start, __setup_end;
  71
  72 #define __setup(str, fn)                                                                \
  73         static char __setup_str_##fn[] __initdata = str;                                \
  74         static struct kernel_param __setup_##fn __initsetup = { __setup_str_##fn, fn }
  75
  76 /*
  77  * Mark functions and data as being only used at initialization
  78  * or exit time.
  79  */
  80 #define __init          __attribute__ ((__section__ (".text.init")))
  81 #define __exit          __attribute__ ((unused, __section__(".text.init")))
  82 #define __initdata      __attribute__ ((__section__ (".data.init")))
  83 #define __exitdata      __attribute__ ((unused, __section__ (".data.init")))
  84 #define __initsetup     __attribute__ ((unused,__section__ (".setup.init")))
  85 #define __init_call     __attribute__ ((unused,__section__ (".initcall.init")))
  86
  87 #define __initfunc(__arginit) \
  88         __arginit __init; \
  89         __arginit
  90
  91 /* For assembly routines */
  92 #define __INIT          .section        ".text.init","ax"
  93 #define __FINIT         .previous
  94 #define __INITDATA      .section        ".data.init","aw"
  95
  96 #define module_init(x)  __initcall(x);
  97 #define module_exit(x)  /* nothing */
  98
  99 #else
 100
 101 #define __init
 102 #define __exit
 103 #define __initdata
 104 #define __exitdata
 105 #define __initfunc(__arginit) __arginit
 106 #define __initcall
 107 /* For assembly routines */
 108 #define __INIT
 109 #define __FINIT
 110 #define __INITDATA
 111
 112 /* Not sure what version aliases were introduced in, but certainly in 2.95.  */
 113 #if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95)
 114 #define module_init(x)  int init_module(void) __attribute__((alias(#x)));
 115 #define module_exit(x)  void cleanup_module(void) __attribute__((alias(#x)));
 116 #else
 117 #define module_init(x)  int init_module(void) { return x(); }
 118 #define module_exit(x)  void cleanup_module(void) { x(); }
 119 #endif
 120
 121 #endif
 122
 123 #if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 8)
 124 #define __initlocaldata  __initdata
 125 #else
 126 #define __initlocaldata
 127 #endif
 128
 129 #endif