linux/include/linux/init.h
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   1#ifndef _LINUX_INIT_H
   2#define _LINUX_INIT_H
   3
   4#include <linux/compiler.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 * Also note, that this data cannot be "const".
  39 */
  40
  41/* These are for everybody (although not all archs will actually
  42   discard it in modules) */
  43#define __init          __attribute__ ((__section__ (".init.text")))
  44#define __initdata      __attribute__ ((__section__ (".init.data")))
  45#define __exitdata      __attribute__ ((__section__(".exit.data")))
  46#define __exit_call     __attribute_used__ __attribute__ ((__section__ (".exitcall.exit")))
  47
  48/* modpost check for section mismatches during the kernel build.
  49 * A section mismatch happens when there are references from a
  50 * code or data section to an init section (both code or data).
  51 * The init sections are (for most archs) discarded by the kernel
  52 * when early init has completed so all such references are potential bugs.
  53 * For exit sections the same issue exists.
  54 * The following markers are used for the cases where the reference to
  55 * the init/exit section (code or data) is valid and will teach modpost
  56 * not to issue a warning.
  57 * The markers follow same syntax rules as __init / __initdata. */
  58#define __init_refok     noinline __attribute__ ((__section__ (".text.init.refok")))
  59#define __initdata_refok          __attribute__ ((__section__ (".data.init.refok")))
  60
  61#ifdef MODULE
  62#define __exit          __attribute__ ((__section__(".exit.text")))
  63#else
  64#define __exit          __attribute_used__ __attribute__ ((__section__(".exit.text")))
  65#endif
  66
  67/* For assembly routines */
  68#define __INIT          .section        ".init.text","ax"
  69#define __FINIT         .previous
  70#define __INITDATA      .section        ".init.data","aw"
  71
  72#ifndef __ASSEMBLY__
  73/*
  74 * Used for initialization calls..
  75 */
  76typedef int (*initcall_t)(void);
  77typedef void (*exitcall_t)(void);
  78
  79extern initcall_t __con_initcall_start[], __con_initcall_end[];
  80extern initcall_t __security_initcall_start[], __security_initcall_end[];
  81
  82/* Defined in init/main.c */
  83extern char __initdata boot_command_line[];
  84extern char *saved_command_line;
  85extern unsigned int reset_devices;
  86
  87/* used by init/main.c */
  88void setup_arch(char **);
  89void prepare_namespace(void);
  90
  91#endif
  92  
  93#ifndef MODULE
  94
  95#ifndef __ASSEMBLY__
  96
  97/* initcalls are now grouped by functionality into separate 
  98 * subsections. Ordering inside the subsections is determined
  99 * by link order. 
 100 * For backwards compatibility, initcall() puts the call in 
 101 * the device init subsection.
 102 *
 103 * The `id' arg to __define_initcall() is needed so that multiple initcalls
 104 * can point at the same handler without causing duplicate-symbol build errors.
 105 */
 106
 107#define __define_initcall(level,fn,id) \
 108        static initcall_t __initcall_##fn##id __attribute_used__ \
 109        __attribute__((__section__(".initcall" level ".init"))) = fn
 110
 111/*
 112 * A "pure" initcall has no dependencies on anything else, and purely
 113 * initializes variables that couldn't be statically initialized.
 114 *
 115 * This only exists for built-in code, not for modules.
 116 */
 117#define pure_initcall(fn)               __define_initcall("0",fn,1)
 118
 119#define core_initcall(fn)               __define_initcall("1",fn,1)
 120#define core_initcall_sync(fn)          __define_initcall("1s",fn,1s)
 121#define postcore_initcall(fn)           __define_initcall("2",fn,2)
 122#define postcore_initcall_sync(fn)      __define_initcall("2s",fn,2s)
 123#define arch_initcall(fn)               __define_initcall("3",fn,3)
 124#define arch_initcall_sync(fn)          __define_initcall("3s",fn,3s)
 125#define subsys_initcall(fn)             __define_initcall("4",fn,4)
 126#define subsys_initcall_sync(fn)        __define_initcall("4s",fn,4s)
 127#define fs_initcall(fn)                 __define_initcall("5",fn,5)
 128#define fs_initcall_sync(fn)            __define_initcall("5s",fn,5s)
 129#define rootfs_initcall(fn)             __define_initcall("rootfs",fn,rootfs)
 130#define device_initcall(fn)             __define_initcall("6",fn,6)
 131#define device_initcall_sync(fn)        __define_initcall("6s",fn,6s)
 132#define late_initcall(fn)               __define_initcall("7",fn,7)
 133#define late_initcall_sync(fn)          __define_initcall("7s",fn,7s)
 134
 135#define __initcall(fn) device_initcall(fn)
 136
 137#define __exitcall(fn) \
 138        static exitcall_t __exitcall_##fn __exit_call = fn
 139
 140#define console_initcall(fn) \
 141        static initcall_t __initcall_##fn \
 142        __attribute_used__ __attribute__((__section__(".con_initcall.init")))=fn
 143
 144#define security_initcall(fn) \
 145        static initcall_t __initcall_##fn \
 146        __attribute_used__ __attribute__((__section__(".security_initcall.init"))) = fn
 147
 148struct obs_kernel_param {
 149        const char *str;
 150        int (*setup_func)(char *);
 151        int early;
 152};
 153
 154/*
 155 * Only for really core code.  See moduleparam.h for the normal way.
 156 *
 157 * Force the alignment so the compiler doesn't space elements of the
 158 * obs_kernel_param "array" too far apart in .init.setup.
 159 */
 160#define __setup_param(str, unique_id, fn, early)                        \
 161        static char __setup_str_##unique_id[] __initdata = str; \
 162        static struct obs_kernel_param __setup_##unique_id      \
 163                __attribute_used__                              \
 164                __attribute__((__section__(".init.setup")))     \
 165                __attribute__((aligned((sizeof(long)))))        \
 166                = { __setup_str_##unique_id, fn, early }
 167
 168#define __setup_null_param(str, unique_id)                      \
 169        __setup_param(str, unique_id, NULL, 0)
 170
 171#define __setup(str, fn)                                        \
 172        __setup_param(str, fn, fn, 0)
 173
 174#define __obsolete_setup(str)                                   \
 175        __setup_null_param(str, __LINE__)
 176
 177/* NOTE: fn is as per module_param, not __setup!  Emits warning if fn
 178 * returns non-zero. */
 179#define early_param(str, fn)                                    \
 180        __setup_param(str, fn, fn, 1)
 181
 182/* Relies on boot_command_line being set */
 183void __init parse_early_param(void);
 184#endif /* __ASSEMBLY__ */
 185
 186/**
 187 * module_init() - driver initialization entry point
 188 * @x: function to be run at kernel boot time or module insertion
 189 * 
 190 * module_init() will either be called during do_initcalls() (if
 191 * builtin) or at module insertion time (if a module).  There can only
 192 * be one per module.
 193 */
 194#define module_init(x)  __initcall(x);
 195
 196/**
 197 * module_exit() - driver exit entry point
 198 * @x: function to be run when driver is removed
 199 * 
 200 * module_exit() will wrap the driver clean-up code
 201 * with cleanup_module() when used with rmmod when
 202 * the driver is a module.  If the driver is statically
 203 * compiled into the kernel, module_exit() has no effect.
 204 * There can only be one per module.
 205 */
 206#define module_exit(x)  __exitcall(x);
 207
 208#else /* MODULE */
 209
 210/* Don't use these in modules, but some people do... */
 211#define core_initcall(fn)               module_init(fn)
 212#define postcore_initcall(fn)           module_init(fn)
 213#define arch_initcall(fn)               module_init(fn)
 214#define subsys_initcall(fn)             module_init(fn)
 215#define fs_initcall(fn)                 module_init(fn)
 216#define device_initcall(fn)             module_init(fn)
 217#define late_initcall(fn)               module_init(fn)
 218
 219#define security_initcall(fn)           module_init(fn)
 220
 221/* These macros create a dummy inline: gcc 2.9x does not count alias
 222 as usage, hence the `unused function' warning when __init functions
 223 are declared static. We use the dummy __*_module_inline functions
 224 both to kill the warning and check the type of the init/cleanup
 225 function. */
 226
 227/* Each module must use one module_init(), or one no_module_init */
 228#define module_init(initfn)                                     \
 229        static inline initcall_t __inittest(void)               \
 230        { return initfn; }                                      \
 231        int init_module(void) __attribute__((alias(#initfn)));
 232
 233/* This is only required if you want to be unloadable. */
 234#define module_exit(exitfn)                                     \
 235        static inline exitcall_t __exittest(void)               \
 236        { return exitfn; }                                      \
 237        void cleanup_module(void) __attribute__((alias(#exitfn)));
 238
 239#define __setup_param(str, unique_id, fn)       /* nothing */
 240#define __setup_null_param(str, unique_id)      /* nothing */
 241#define __setup(str, func)                      /* nothing */
 242#define __obsolete_setup(str)                   /* nothing */
 243#endif
 244
 245/* Data marked not to be saved by software suspend */
 246#define __nosavedata __attribute__ ((__section__ (".data.nosave")))
 247
 248/* This means "can be init if no module support, otherwise module load
 249   may call it." */
 250#ifdef CONFIG_MODULES
 251#define __init_or_module
 252#define __initdata_or_module
 253#else
 254#define __init_or_module __init
 255#define __initdata_or_module __initdata
 256#endif /*CONFIG_MODULES*/
 257
 258#ifdef CONFIG_HOTPLUG
 259#define __devinit
 260#define __devinitdata
 261#define __devexit
 262#define __devexitdata
 263#else
 264#define __devinit __init
 265#define __devinitdata __initdata
 266#define __devexit __exit
 267#define __devexitdata __exitdata
 268#endif
 269
 270#ifdef CONFIG_HOTPLUG_CPU
 271#define __cpuinit
 272#define __cpuinitdata
 273#define __cpuexit
 274#define __cpuexitdata
 275#else
 276#define __cpuinit       __init
 277#define __cpuinitdata __initdata
 278#define __cpuexit __exit
 279#define __cpuexitdata   __exitdata
 280#endif
 281
 282#if defined(CONFIG_MEMORY_HOTPLUG) || defined(CONFIG_ACPI_HOTPLUG_MEMORY) \
 283        || defined(CONFIG_ACPI_HOTPLUG_MEMORY_MODULE)
 284#define __meminit
 285#define __meminitdata
 286#define __memexit
 287#define __memexitdata
 288#else
 289#define __meminit       __init
 290#define __meminitdata __initdata
 291#define __memexit __exit
 292#define __memexitdata   __exitdata
 293#endif
 294
 295/* Functions marked as __devexit may be discarded at kernel link time, depending
 296   on config options.  Newer versions of binutils detect references from
 297   retained sections to discarded sections and flag an error.  Pointers to
 298   __devexit functions must use __devexit_p(function_name), the wrapper will
 299   insert either the function_name or NULL, depending on the config options.
 300 */
 301#if defined(MODULE) || defined(CONFIG_HOTPLUG)
 302#define __devexit_p(x) x
 303#else
 304#define __devexit_p(x) NULL
 305#endif
 306
 307#ifdef MODULE
 308#define __exit_p(x) x
 309#else
 310#define __exit_p(x) NULL
 311#endif
 312
 313#endif /* _LINUX_INIT_H */
 314
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