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remarkable-linux/include/linux/init.h
Pavel Emelyanov 4665079cbb [NETNS]: Move some code into __init section when CONFIG_NET_NS=n 
With the net namespaces many code leaved the __init section,
thus making the kernel occupy more memory than it did before.
Since we have a config option that prohibits the namespace
creation, the functions that initialize/finalize some netns
stuff are simply not needed and can be freed after the boot.

Currently, this is almost not noticeable, since few calls
are no longer in __init, but when the namespaces will be
merged it will be possible to free more code. I propose to
use the __net_init, __net_exit and __net_initdata "attributes"
for functions/variables that are not used if the CONFIG_NET_NS
is not set to save more space in memory.

The exiting functions cannot just reside in the __exit section,
as noticed by David, since the init section will have
references on it and the compilation will fail due to modpost
checks. These references can exist, since the init namespace
never dies and the exit callbacks are never called. So I
introduce the __exit_refok attribute just like it is already
done with the __init_refok.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 16:54:58 -07:00

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#ifndef _LINUX_INIT_H
#define _LINUX_INIT_H
#include <linux/compiler.h>
/* These macros are used to mark some functions or
* initialized data (doesn't apply to uninitialized data)
* as `initialization' functions. The kernel can take this
* as hint that the function is used only during the initialization
* phase and free up used memory resources after
*
* Usage:
* For functions:
*
* You should add __init immediately before the function name, like:
*
* static void __init initme(int x, int y)
* {
* extern int z; z = x * y;
* }
*
* If the function has a prototype somewhere, you can also add
* __init between closing brace of the prototype and semicolon:
*
* extern int initialize_foobar_device(int, int, int) __init;
*
* For initialized data:
* You should insert __initdata between the variable name and equal
* sign followed by value, e.g.:
*
* static int init_variable __initdata = 0;
* static char linux_logo[] __initdata = { 0x32, 0x36, ... };
*
* Don't forget to initialize data not at file scope, i.e. within a function,
* as gcc otherwise puts the data into the bss section and not into the init
* section.
*
* Also note, that this data cannot be "const".
*/
/* These are for everybody (although not all archs will actually
discard it in modules) */
#define __init __attribute__ ((__section__ (".init.text"))) __cold
#define __initdata __attribute__ ((__section__ (".init.data")))
#define __exitdata __attribute__ ((__section__(".exit.data")))
#define __exit_call __attribute_used__ __attribute__ ((__section__ (".exitcall.exit")))
/* modpost check for section mismatches during the kernel build.
* A section mismatch happens when there are references from a
* code or data section to an init section (both code or data).
* The init sections are (for most archs) discarded by the kernel
* when early init has completed so all such references are potential bugs.
* For exit sections the same issue exists.
* The following markers are used for the cases where the reference to
* the init/exit section (code or data) is valid and will teach modpost
* not to issue a warning.
* The markers follow same syntax rules as __init / __initdata. */
#define __init_refok noinline __attribute__ ((__section__ (".text.init.refok")))
#define __initdata_refok __attribute__ ((__section__ (".data.init.refok")))
#define __exit_refok noinline __attribute__ ((__section__ (".exit.text.refok")))
#ifdef MODULE
#define __exit __attribute__ ((__section__(".exit.text"))) __cold
#else
#define __exit __attribute_used__ __attribute__ ((__section__(".exit.text"))) __cold
#endif
/* For assembly routines */
#define __INIT .section ".init.text","ax"
#define __FINIT .previous
#define __INITDATA .section ".init.data","aw"
#ifndef __ASSEMBLY__
/*
* Used for initialization calls..
*/
typedef int (*initcall_t)(void);
typedef void (*exitcall_t)(void);
extern initcall_t __con_initcall_start[], __con_initcall_end[];
extern initcall_t __security_initcall_start[], __security_initcall_end[];
/* Defined in init/main.c */
extern char __initdata boot_command_line[];
extern char *saved_command_line;
extern unsigned int reset_devices;
/* used by init/main.c */
void setup_arch(char **);
void prepare_namespace(void);
#endif
#ifndef MODULE
#ifndef __ASSEMBLY__
/* initcalls are now grouped by functionality into separate
* subsections. Ordering inside the subsections is determined
* by link order.
* For backwards compatibility, initcall() puts the call in
* the device init subsection.
*
* The `id' arg to __define_initcall() is needed so that multiple initcalls
* can point at the same handler without causing duplicate-symbol build errors.
*/
#define __define_initcall(level,fn,id) \
static initcall_t __initcall_##fn##id __attribute_used__ \
__attribute__((__section__(".initcall" level ".init"))) = fn
/*
* A "pure" initcall has no dependencies on anything else, and purely
* initializes variables that couldn't be statically initialized.
*
* This only exists for built-in code, not for modules.
*/
#define pure_initcall(fn) __define_initcall("0",fn,0)
#define core_initcall(fn) __define_initcall("1",fn,1)
#define core_initcall_sync(fn) __define_initcall("1s",fn,1s)
#define postcore_initcall(fn) __define_initcall("2",fn,2)
#define postcore_initcall_sync(fn) __define_initcall("2s",fn,2s)
#define arch_initcall(fn) __define_initcall("3",fn,3)
#define arch_initcall_sync(fn) __define_initcall("3s",fn,3s)
#define subsys_initcall(fn) __define_initcall("4",fn,4)
#define subsys_initcall_sync(fn) __define_initcall("4s",fn,4s)
#define fs_initcall(fn) __define_initcall("5",fn,5)
#define fs_initcall_sync(fn) __define_initcall("5s",fn,5s)
#define rootfs_initcall(fn) __define_initcall("rootfs",fn,rootfs)
#define device_initcall(fn) __define_initcall("6",fn,6)
#define device_initcall_sync(fn) __define_initcall("6s",fn,6s)
#define late_initcall(fn) __define_initcall("7",fn,7)
#define late_initcall_sync(fn) __define_initcall("7s",fn,7s)
#define __initcall(fn) device_initcall(fn)
#define __exitcall(fn) \
static exitcall_t __exitcall_##fn __exit_call = fn
#define console_initcall(fn) \
static initcall_t __initcall_##fn \
__attribute_used__ __attribute__((__section__(".con_initcall.init")))=fn
#define security_initcall(fn) \
static initcall_t __initcall_##fn \
__attribute_used__ __attribute__((__section__(".security_initcall.init"))) = fn
struct obs_kernel_param {
const char *str;
int (*setup_func)(char *);
int early;
};
/*
* Only for really core code. See moduleparam.h for the normal way.
*
* Force the alignment so the compiler doesn't space elements of the
* obs_kernel_param "array" too far apart in .init.setup.
*/
#define __setup_param(str, unique_id, fn, early) \
static char __setup_str_##unique_id[] __initdata = str; \
static struct obs_kernel_param __setup_##unique_id \
__attribute_used__ \
__attribute__((__section__(".init.setup"))) \
__attribute__((aligned((sizeof(long))))) \
= { __setup_str_##unique_id, fn, early }
#define __setup_null_param(str, unique_id) \
__setup_param(str, unique_id, NULL, 0)
#define __setup(str, fn) \
__setup_param(str, fn, fn, 0)
/* NOTE: fn is as per module_param, not __setup! Emits warning if fn
* returns non-zero. */
#define early_param(str, fn) \
__setup_param(str, fn, fn, 1)
/* Relies on boot_command_line being set */
void __init parse_early_param(void);
#endif /* __ASSEMBLY__ */
/**
* module_init() - driver initialization entry point
* @x: function to be run at kernel boot time or module insertion
*
* module_init() will either be called during do_initcalls() (if
* builtin) or at module insertion time (if a module). There can only
* be one per module.
*/
#define module_init(x) __initcall(x);
/**
* module_exit() - driver exit entry point
* @x: function to be run when driver is removed
*
* module_exit() will wrap the driver clean-up code
* with cleanup_module() when used with rmmod when
* the driver is a module. If the driver is statically
* compiled into the kernel, module_exit() has no effect.
* There can only be one per module.
*/
#define module_exit(x) __exitcall(x);
#else /* MODULE */
/* Don't use these in modules, but some people do... */
#define core_initcall(fn) module_init(fn)
#define postcore_initcall(fn) module_init(fn)
#define arch_initcall(fn) module_init(fn)
#define subsys_initcall(fn) module_init(fn)
#define fs_initcall(fn) module_init(fn)
#define device_initcall(fn) module_init(fn)
#define late_initcall(fn) module_init(fn)
#define security_initcall(fn) module_init(fn)
/* These macros create a dummy inline: gcc 2.9x does not count alias
as usage, hence the `unused function' warning when __init functions
are declared static. We use the dummy __*_module_inline functions
both to kill the warning and check the type of the init/cleanup
function. */
/* Each module must use one module_init(), or one no_module_init */
#define module_init(initfn) \
static inline initcall_t __inittest(void) \
{ return initfn; } \
int init_module(void) __attribute__((alias(#initfn)));
/* This is only required if you want to be unloadable. */
#define module_exit(exitfn) \
static inline exitcall_t __exittest(void) \
{ return exitfn; } \
void cleanup_module(void) __attribute__((alias(#exitfn)));
#define __setup_param(str, unique_id, fn) /* nothing */
#define __setup_null_param(str, unique_id) /* nothing */
#define __setup(str, func) /* nothing */
#endif
/* Data marked not to be saved by software suspend */
#define __nosavedata __attribute__ ((__section__ (".data.nosave")))
/* This means "can be init if no module support, otherwise module load
may call it." */
#ifdef CONFIG_MODULES
#define __init_or_module
#define __initdata_or_module
#else
#define __init_or_module __init
#define __initdata_or_module __initdata
#endif /*CONFIG_MODULES*/
#ifdef CONFIG_HOTPLUG
#define __devinit
#define __devinitdata
#define __devexit
#define __devexitdata
#else
#define __devinit __init
#define __devinitdata __initdata
#define __devexit __exit
#define __devexitdata __exitdata
#endif
#ifdef CONFIG_HOTPLUG_CPU
#define __cpuinit
#define __cpuinitdata
#define __cpuexit
#define __cpuexitdata
#else
#define __cpuinit __init
#define __cpuinitdata __initdata
#define __cpuexit __exit
#define __cpuexitdata __exitdata
#endif
#if defined(CONFIG_MEMORY_HOTPLUG) || defined(CONFIG_ACPI_HOTPLUG_MEMORY) \
|| defined(CONFIG_ACPI_HOTPLUG_MEMORY_MODULE)
#define __meminit
#define __meminitdata
#define __memexit
#define __memexitdata
#else
#define __meminit __init
#define __meminitdata __initdata
#define __memexit __exit
#define __memexitdata __exitdata
#endif
/* Functions marked as __devexit may be discarded at kernel link time, depending
on config options. Newer versions of binutils detect references from
retained sections to discarded sections and flag an error. Pointers to
__devexit functions must use __devexit_p(function_name), the wrapper will
insert either the function_name or NULL, depending on the config options.
*/
#if defined(MODULE) || defined(CONFIG_HOTPLUG)
#define __devexit_p(x) x
#else
#define __devexit_p(x) NULL
#endif
#ifdef MODULE
#define __exit_p(x) x
#else
#define __exit_p(x) NULL
#endif
#endif /* _LINUX_INIT_H */
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