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  * If the function has a prototype somewhere, you can also add
  21  * __init between closing brace of the prototype and semicolon:
  22  *
  23  * extern int initialize_foobar_device(int, int, int) __init;
  24  *
  25  * For initialized data:
  26  * You should insert __initdata between the variable name and equal
  27  * sign followed by value, e.g.:
  28  *
  29  * static int init_variable __initdata = 0;
  30  * static char linux_logo[] __initdata = { 0x32, 0x36, ... };
  31  *
  32  * For initialized data not at file scope, i.e. within a function,
  33  * you should use __initlocaldata instead, due to a bug in GCC 2.7.
  34  */
  35
  36 #ifndef MODULE
  37
  38 #ifndef __ASSEMBLY__
  39
  40 /*
  41  * Used for initialization calls..
  42  */
  43 typedef int (*initcall_t)(void);
  44
  45 extern initcall_t __initcall_start, __initcall_end;
  46
  47 #define __initcall(fn)                                                          \
  48         static initcall_t __initcall_##fn __init_call = fn
  49
  50 /*
  51  * Used for kernel command line parameter setup
  52  */
  53 struct kernel_param {
  54         const char *str;
  55         int (*setup_func)(char *);
  56 };
  57
  58 extern struct kernel_param __setup_start, __setup_end;
  59
  60 #define __setup(str, fn)                                                                \
  61         static char __setup_str_##fn[] __initdata = str;                                \
  62         static struct kernel_param __setup_##fn __initsetup = { __setup_str_##fn, fn }
  63
  64 #endif /* __ASSEMBLY__ */
  65
  66 /*
  67  * Mark functions and data as being only used at initialization
  68  * or exit time.
  69  */
  70 #define __init          __attribute__ ((__section__ (".text.init")))
  71 #define __exit          __attribute__ ((unused, __section__(".text.init")))
  72 #define __initdata      __attribute__ ((__section__ (".data.init")))
  73 #define __exitdata      __attribute__ ((unused, __section__ (".data.init")))
  74 #define __initsetup     __attribute__ ((unused,__section__ (".setup.init")))
  75 #define __init_call     __attribute__ ((unused,__section__ (".initcall.init")))
  76
  77 /* For assembly routines */
  78 #define __INIT          .section        ".text.init","ax"
  79 #define __FINIT         .previous
  80 #define __INITDATA      .section        ".data.init","aw"
  81
  82 #define module_init(x)  __initcall(x);
  83 #define module_exit(x)  /* nothing */
  84
  85 #else
  86
  87 #define __init
  88 #define __exit
  89 #define __initdata
  90 #define __exitdata
  91 #define __initcall
  92 /* For assembly routines */
  93 #define __INIT
  94 #define __FINIT
  95 #define __INITDATA
  96
  97 /* Not sure what version aliases were introduced in, but certainly in 2.95.  */
  98 #if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95)
  99 #define module_init(x)  int init_module(void) __attribute__((alias(#x)));
 100 #define module_exit(x)  void cleanup_module(void) __attribute__((alias(#x)));
 101 #else
 102 #define module_init(x)  int init_module(void) { return x(); }
 103 #define module_exit(x)  void cleanup_module(void) { x(); }
 104 #endif
 105
 106 #endif
 107
 108 #if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 8)
 109 #define __initlocaldata  __initdata
 110 #else
 111 #define __initlocaldata
 112 #endif
 113
 114 #endif