include/linux/init.h

   1 #ifndef _LINUX_INIT_H
   2 #define _LINUX_INIT_H
   3
   4 #include <linux/config.h>
   5 #include <linux/compiler.h>
   6
   7 /* These macros are used to mark some functions or
   8  * initialized data (doesn't apply to uninitialized data)
   9  * as `initialization' functions. The kernel can take this
  10  * as hint that the function is used only during the initialization
  11  * phase and free up used memory resources after
  12  *
  13  * Usage:
  14  * For functions:
  15  *
  16  * You should add __init immediately before the function name, like:
  17  *
  18  * static void __init initme(int x, int y)
  19  * {
  20  *    extern int z; z = x * y;
  21  * }
  22  *
  23  * If the function has a prototype somewhere, you can also add
  24  * __init between closing brace of the prototype and semicolon:
  25  *
  26  * extern int initialize_foobar_device(int, int, int) __init;
  27  *
  28  * For initialized data:
  29  * You should insert __initdata between the variable name and equal
  30  * sign followed by value, e.g.:
  31  *
  32  * static int init_variable __initdata = 0;
  33  * static char linux_logo[] __initdata = { 0x32, 0x36, ... };
  34  *
  35  * Don't forget to initialize data not at file scope, i.e. within a function,
  36  * as gcc otherwise puts the data into the bss section and not into the init
  37  * section.
  38  *
  39  * Also note, that this data cannot be "const".
  40  */
  41
  42 /* These are for everybody (although not all archs will actually
  43    discard it in modules) */
  44 #define __init          __attribute__ ((__section__ (".init.text")))
  45 #define __initdata      __attribute__ ((__section__ (".init.data")))
  46 #define __exitdata      __attribute__ ((__section__(".exit.data")))
  47 #define __exit_call     __attribute_used__ __attribute__ ((__section__ (".exitcall.exit")))
  48
  49 #ifdef MODULE
  50 #define __exit          __attribute__ ((__section__(".exit.text")))
  51 #else
  52 #define __exit          __attribute_used__ __attribute__ ((__section__(".exit.text")))
  53 #endif
  54
  55 /* For assembly routines */
  56 #define __INIT          .section        ".init.text","ax"
  57 #define __FINIT         .previous
  58 #define __INITDATA      .section        ".init.data","aw"
  59
  60 #ifndef __ASSEMBLY__
  61 /*
  62  * Used for initialization calls..
  63  */
  64 typedef int (*initcall_t)(void);
  65 typedef void (*exitcall_t)(void);
  66
  67 extern initcall_t __con_initcall_start, __con_initcall_end;
  68 extern initcall_t __security_initcall_start, __security_initcall_end;
  69
  70 /* Defined in init/main.c */
  71 extern char saved_command_line[];
  72 #endif
  73
  74 #ifndef MODULE
  75
  76 #ifndef __ASSEMBLY__
  77
  78 /* initcalls are now grouped by functionality into separate
  79  * subsections. Ordering inside the subsections is determined
  80  * by link order.
  81  * For backwards compatibility, initcall() puts the call in
  82  * the device init subsection.
  83  */
  84
  85 #define __define_initcall(level,fn) \
  86         static initcall_t __initcall_##fn __attribute_used__ \
  87         __attribute__((__section__(".initcall" level ".init"))) = fn
  88
  89 #define core_initcall(fn)               __define_initcall("1",fn)
  90 #define postcore_initcall(fn)           __define_initcall("2",fn)
  91 #define arch_initcall(fn)               __define_initcall("3",fn)
  92 #define subsys_initcall(fn)             __define_initcall("4",fn)
  93 #define fs_initcall(fn)                 __define_initcall("5",fn)
  94 #define device_initcall(fn)             __define_initcall("6",fn)
  95 #define late_initcall(fn)               __define_initcall("7",fn)
  96
  97 #define __initcall(fn) device_initcall(fn)
  98
  99 #define __exitcall(fn) \
 100         static exitcall_t __exitcall_##fn __exit_call = fn
 101
 102 #define console_initcall(fn) \
 103         static initcall_t __initcall_##fn \
 104         __attribute_used__ __attribute__((__section__(".con_initcall.init")))=fn
 105
 106 #define security_initcall(fn) \
 107         static initcall_t __initcall_##fn \
 108         __attribute_used__ __attribute__((__section__(".security_initcall.init"))) = fn
 109
 110 struct obs_kernel_param {
 111         const char *str;
 112         int (*setup_func)(char *);
 113         int early;
 114 };
 115
 116 /*
 117  * Only for really core code.  See moduleparam.h for the normal way.
 118  *
 119  * Force the alignment so the compiler doesn't space elements of the
 120  * obs_kernel_param "array" too far apart in .init.setup.
 121  */
 122 #define __setup_param(str, unique_id, fn, early)                        \
 123         static char __setup_str_##unique_id[] __initdata = str; \
 124         static struct obs_kernel_param __setup_##unique_id      \
 125                 __attribute_used__                              \
 126                 __attribute__((__section__(".init.setup")))     \
 127                 __attribute__((aligned((sizeof(long)))))        \
 128                 = { __setup_str_##unique_id, fn, early }
 129
 130 #define __setup_null_param(str, unique_id)                      \
 131         __setup_param(str, unique_id, NULL, 0)
 132
 133 #define __setup(str, fn)                                        \
 134         __setup_param(str, fn, fn, 0)
 135
 136 #define __obsolete_setup(str)                                   \
 137         __setup_null_param(str, __LINE__)
 138
 139 /* NOTE: fn is as per module_param, not __setup!  Emits warning if fn
 140  * returns non-zero. */
 141 #define early_param(str, fn)                                    \
 142         __setup_param(str, fn, fn, 1)
 143
 144 /* Relies on saved_command_line being set */
 145 void __init parse_early_param(void);
 146 #endif /* __ASSEMBLY__ */
 147
 148 /**
 149  * module_init() - driver initialization entry point
 150  * @x: function to be run at kernel boot time or module insertion
 151  *
 152  * module_init() will either be called during do_initcalls (if
 153  * builtin) or at module insertion time (if a module).  There can only
 154  * be one per module.
 155  */
 156 #define module_init(x)  __initcall(x);
 157
 158 /**
 159  * module_exit() - driver exit entry point
 160  * @x: function to be run when driver is removed
 161  *
 162  * module_exit() will wrap the driver clean-up code
 163  * with cleanup_module() when used with rmmod when
 164  * the driver is a module.  If the driver is statically
 165  * compiled into the kernel, module_exit() has no effect.
 166  * There can only be one per module.
 167  */
 168 #define module_exit(x)  __exitcall(x);
 169
 170 #else /* MODULE */
 171
 172 /* Don't use these in modules, but some people do... */
 173 #define core_initcall(fn)               module_init(fn)
 174 #define postcore_initcall(fn)           module_init(fn)
 175 #define arch_initcall(fn)               module_init(fn)
 176 #define subsys_initcall(fn)             module_init(fn)
 177 #define fs_initcall(fn)                 module_init(fn)
 178 #define device_initcall(fn)             module_init(fn)
 179 #define late_initcall(fn)               module_init(fn)
 180
 181 #define security_initcall(fn)           module_init(fn)
 182
 183 /* These macros create a dummy inline: gcc 2.9x does not count alias
 184  as usage, hence the `unused function' warning when __init functions
 185  are declared static. We use the dummy __*_module_inline functions
 186  both to kill the warning and check the type of the init/cleanup
 187  function. */
 188
 189 /* Each module must use one module_init(), or one no_module_init */
 190 #define module_init(initfn)                                     \
 191         static inline initcall_t __inittest(void)               \
 192         { return initfn; }                                      \
 193         int init_module(void) __attribute__((alias(#initfn)));
 194
 195 /* This is only required if you want to be unloadable. */
 196 #define module_exit(exitfn)                                     \
 197         static inline exitcall_t __exittest(void)               \
 198         { return exitfn; }                                      \
 199         void cleanup_module(void) __attribute__((alias(#exitfn)));
 200
 201 #define __setup_param(str, unique_id, fn)       /* nothing */
 202 #define __setup_null_param(str, unique_id)      /* nothing */
 203 #define __setup(str, func)                      /* nothing */
 204 #define __obsolete_setup(str)                   /* nothing */
 205 #endif
 206
 207 /* Data marked not to be saved by software_suspend() */
 208 #define __nosavedata __attribute__ ((__section__ (".data.nosave")))
 209
 210 /* This means "can be init if no module support, otherwise module load
 211    may call it." */
 212 #ifdef CONFIG_MODULES
 213 #define __init_or_module
 214 #define __initdata_or_module
 215 #else
 216 #define __init_or_module __init
 217 #define __initdata_or_module __initdata
 218 #endif /*CONFIG_MODULES*/
 219
 220 #ifdef CONFIG_HOTPLUG
 221 #define __devinit
 222 #define __devinitdata
 223 #define __devexit
 224 #define __devexitdata
 225 #else
 226 #define __devinit __init
 227 #define __devinitdata __initdata
 228 #define __devexit __exit
 229 #define __devexitdata __exitdata
 230 #endif
 231
 232 /* Functions marked as __devexit may be discarded at kernel link time, depending
 233    on config options.  Newer versions of binutils detect references from
 234    retained sections to discarded sections and flag an error.  Pointers to
 235    __devexit functions must use __devexit_p(function_name), the wrapper will
 236    insert either the function_name or NULL, depending on the config options.
 237  */
 238 #if defined(MODULE) || defined(CONFIG_HOTPLUG)
 239 #define __devexit_p(x) x
 240 #else
 241 #define __devexit_p(x) NULL
 242 #endif
 243
 244 #ifdef MODULE
 245 #define __exit_p(x) x
 246 #else
 247 #define __exit_p(x) NULL
 248 #endif
 249
 250 #endif /* _LINUX_INIT_H */