include/linux/init.h

   1 #ifndef _LINUX_INIT_H
   2 #define _LINUX_INIT_H
   3
   4 #include <linux/config.h>
   5
   6 /* These macros are used to mark some functions or
   7  * initialized data (doesn't apply to uninitialized data)
   8  * as `initialization' functions. The kernel can take this
   9  * as hint that the function is used only during the initialization
  10  * phase and free up used memory resources after
  11  *
  12  * Usage:
  13  * For functions:
  14  *
  15  * You should add __init immediately before the function name, like:
  16  *
  17  * static void __init initme(int x, int y)
  18  * {
  19  *    extern int z; z = x * y;
  20  * }
  21  *
  22  * If the function has a prototype somewhere, you can also add
  23  * __init between closing brace of the prototype and semicolon:
  24  *
  25  * extern int initialize_foobar_device(int, int, int) __init;
  26  *
  27  * For initialized data:
  28  * You should insert __initdata between the variable name and equal
  29  * sign followed by value, e.g.:
  30  *
  31  * static int init_variable __initdata = 0;
  32  * static char linux_logo[] __initdata = { 0x32, 0x36, ... };
  33  *
  34  * Don't forget to initialize data not at file scope, i.e. within a function,
  35  * as gcc otherwise puts the data into the bss section and not into the init
  36  * section.
  37  */
  38
  39 #ifndef MODULE
  40
  41 #ifndef __ASSEMBLY__
  42
  43 /*
  44  * Used for initialization calls..
  45  */
  46 typedef int (*initcall_t)(void);
  47 typedef void (*exitcall_t)(void);
  48
  49 extern initcall_t __initcall_start, __initcall_end;
  50
  51 #define __initcall(fn)                                                          \
  52         static initcall_t __initcall_##fn __init_call = fn
  53 #define __exitcall(fn)                                                          \
  54         static exitcall_t __exitcall_##fn __exit_call = fn
  55
  56 /*
  57  * Used for kernel command line parameter setup
  58  */
  59 struct kernel_param {
  60         const char *str;
  61         int (*setup_func)(char *);
  62 };
  63
  64 extern struct kernel_param __setup_start, __setup_end;
  65
  66 #define __setup(str, fn)                                                                \
  67         static char __setup_str_##fn[] __initdata = str;                                \
  68         static struct kernel_param __setup_##fn __initsetup = { __setup_str_##fn, fn }
  69
  70 #endif /* __ASSEMBLY__ */
  71
  72 /*
  73  * Mark functions and data as being only used at initialization
  74  * or exit time.
  75  */
  76 #define __init          __attribute__ ((__section__ (".text.init")))
  77 #define __exit          __attribute__ ((unused, __section__(".text.exit")))
  78 #define __initdata      __attribute__ ((__section__ (".data.init")))
  79 #define __exitdata      __attribute__ ((unused, __section__ (".data.exit")))
  80 #define __initsetup     __attribute__ ((unused,__section__ (".setup.init")))
  81 #define __init_call     __attribute__ ((unused,__section__ (".initcall.init")))
  82 #define __exit_call     __attribute__ ((unused,__section__ (".exitcall.exit")))
  83
  84 /* For assembly routines */
  85 #define __INIT          .section        ".text.init","ax"
  86 #define __FINIT         .previous
  87 #define __INITDATA      .section        ".data.init","aw"
  88
  89 #define module_init(x)  __initcall(x);
  90 #define module_exit(x)  __exitcall(x);
  91
  92 #else
  93
  94 #define __init
  95 #define __exit
  96 #define __initdata
  97 #define __exitdata
  98 #define __initcall(fn)
  99 /* For assembly routines */
 100 #define __INIT
 101 #define __FINIT
 102 #define __INITDATA
 103
 104 /* These macros create a dummy inline: gcc 2.9x does not count alias
 105  as usage, hence the `unused function' warning when __init functions
 106  are declared static. We use the dummy __*_module_inline functions
 107  both to kill the warning and check the type of the init/cleanup
 108  function. */
 109 typedef int (*__init_module_func_t)(void);
 110 typedef void (*__cleanup_module_func_t)(void);
 111 #define module_init(x) \
 112         int init_module(void) __attribute__((alias(#x))); \
 113         extern inline __init_module_func_t __init_module_inline(void) \
 114         { return x; }
 115 #define module_exit(x) \
 116         void cleanup_module(void) __attribute__((alias(#x))); \
 117         extern inline __cleanup_module_func_t __cleanup_module_inline(void) \
 118         { return x; }
 119
 120 #define __setup(str,func) /* nothing */
 121
 122 #endif
 123
 124 #ifdef CONFIG_HOTPLUG
 125 #define __devinit
 126 #define __devinitdata
 127 #define __devexit
 128 #define __devexitdata
 129 #else
 130 #define __devinit __init
 131 #define __devinitdata __initdata
 132 #define __devexit __exit
 133 #define __devexitdata __exitdata
 134 #endif
 135
 136 #endif /* _LINUX_INIT_H */