5ea081785d
The __ref* tags may have been confusing for new kernel developers (I was confused by them for sure) so adding a few more sentences to comment to clear things up for people who see those for the first time. Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com> Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Acked-by: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
350 lines
12 KiB
C
350 lines
12 KiB
C
#ifndef _LINUX_INIT_H
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#define _LINUX_INIT_H
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#include <linux/compiler.h>
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/* These macros are used to mark some functions or
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* initialized data (doesn't apply to uninitialized data)
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* as `initialization' functions. The kernel can take this
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* as hint that the function is used only during the initialization
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* phase and free up used memory resources after
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*
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* Usage:
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* For functions:
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*
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* You should add __init immediately before the function name, like:
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*
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* static void __init initme(int x, int y)
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* {
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* extern int z; z = x * y;
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* }
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*
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* If the function has a prototype somewhere, you can also add
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* __init between closing brace of the prototype and semicolon:
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*
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* extern int initialize_foobar_device(int, int, int) __init;
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*
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* For initialized data:
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* You should insert __initdata between the variable name and equal
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* sign followed by value, e.g.:
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*
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* static int init_variable __initdata = 0;
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* static const char linux_logo[] __initconst = { 0x32, 0x36, ... };
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*
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* Don't forget to initialize data not at file scope, i.e. within a function,
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* as gcc otherwise puts the data into the bss section and not into the init
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* section.
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*
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* Also note, that this data cannot be "const".
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*/
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/* These are for everybody (although not all archs will actually
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discard it in modules) */
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#define __init __section(.init.text) __cold notrace
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#define __initdata __section(.init.data)
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#define __initconst __section(.init.rodata)
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#define __exitdata __section(.exit.data)
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#define __exit_call __used __section(.exitcall.exit)
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/*
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* modpost check for section mismatches during the kernel build.
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* A section mismatch happens when there are references from a
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* code or data section to an init section (both code or data).
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* The init sections are (for most archs) discarded by the kernel
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* when early init has completed so all such references are potential bugs.
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* For exit sections the same issue exists.
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*
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* The following markers are used for the cases where the reference to
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* the *init / *exit section (code or data) is valid and will teach
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* modpost not to issue a warning. Intended semantics is that a code or
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* data tagged __ref* can reference code or data from init section without
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* producing a warning (of course, no warning does not mean code is
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* correct, so optimally document why the __ref is needed and why it's OK).
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*
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* The markers follow same syntax rules as __init / __initdata.
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*/
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#define __ref __section(.ref.text) noinline
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#define __refdata __section(.ref.data)
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#define __refconst __section(.ref.rodata)
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/* compatibility defines */
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#define __init_refok __ref
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#define __initdata_refok __refdata
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#define __exit_refok __ref
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#ifdef MODULE
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#define __exitused
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#else
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#define __exitused __used
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#endif
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#define __exit __section(.exit.text) __exitused __cold
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/* Used for HOTPLUG */
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#define __devinit __section(.devinit.text) __cold
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#define __devinitdata __section(.devinit.data)
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#define __devinitconst __section(.devinit.rodata)
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#define __devexit __section(.devexit.text) __exitused __cold
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#define __devexitdata __section(.devexit.data)
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#define __devexitconst __section(.devexit.rodata)
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/* Used for HOTPLUG_CPU */
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#define __cpuinit __section(.cpuinit.text) __cold
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#define __cpuinitdata __section(.cpuinit.data)
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#define __cpuinitconst __section(.cpuinit.rodata)
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#define __cpuexit __section(.cpuexit.text) __exitused __cold
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#define __cpuexitdata __section(.cpuexit.data)
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#define __cpuexitconst __section(.cpuexit.rodata)
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/* Used for MEMORY_HOTPLUG */
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#define __meminit __section(.meminit.text) __cold
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#define __meminitdata __section(.meminit.data)
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#define __meminitconst __section(.meminit.rodata)
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#define __memexit __section(.memexit.text) __exitused __cold
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#define __memexitdata __section(.memexit.data)
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#define __memexitconst __section(.memexit.rodata)
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/* For assembly routines */
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#define __HEAD .section ".head.text","ax"
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#define __INIT .section ".init.text","ax"
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#define __FINIT .previous
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#define __INITDATA .section ".init.data","aw",%progbits
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#define __INITRODATA .section ".init.rodata","a",%progbits
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#define __FINITDATA .previous
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#define __DEVINIT .section ".devinit.text", "ax"
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#define __DEVINITDATA .section ".devinit.data", "aw"
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#define __DEVINITRODATA .section ".devinit.rodata", "a"
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#define __CPUINIT .section ".cpuinit.text", "ax"
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#define __CPUINITDATA .section ".cpuinit.data", "aw"
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#define __CPUINITRODATA .section ".cpuinit.rodata", "a"
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#define __MEMINIT .section ".meminit.text", "ax"
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#define __MEMINITDATA .section ".meminit.data", "aw"
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#define __MEMINITRODATA .section ".meminit.rodata", "a"
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/* silence warnings when references are OK */
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#define __REF .section ".ref.text", "ax"
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#define __REFDATA .section ".ref.data", "aw"
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#define __REFCONST .section ".ref.rodata", "a"
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#ifndef __ASSEMBLY__
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/*
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* Used for initialization calls..
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*/
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typedef int (*initcall_t)(void);
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typedef void (*exitcall_t)(void);
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extern initcall_t __con_initcall_start[], __con_initcall_end[];
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extern initcall_t __security_initcall_start[], __security_initcall_end[];
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/* Used for contructor calls. */
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typedef void (*ctor_fn_t)(void);
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/* Defined in init/main.c */
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extern int do_one_initcall(initcall_t fn);
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extern char __initdata boot_command_line[];
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extern char *saved_command_line;
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extern unsigned int reset_devices;
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/* used by init/main.c */
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void setup_arch(char **);
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void prepare_namespace(void);
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extern void (*late_time_init)(void);
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extern int initcall_debug;
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#endif
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#ifndef MODULE
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#ifndef __ASSEMBLY__
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/* initcalls are now grouped by functionality into separate
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* subsections. Ordering inside the subsections is determined
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* by link order.
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* For backwards compatibility, initcall() puts the call in
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* the device init subsection.
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*
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* The `id' arg to __define_initcall() is needed so that multiple initcalls
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* can point at the same handler without causing duplicate-symbol build errors.
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*/
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#define __define_initcall(level,fn,id) \
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static initcall_t __initcall_##fn##id __used \
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__attribute__((__section__(".initcall" level ".init"))) = fn
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/*
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* Early initcalls run before initializing SMP.
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*
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* Only for built-in code, not modules.
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*/
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#define early_initcall(fn) __define_initcall("early",fn,early)
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/*
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* A "pure" initcall has no dependencies on anything else, and purely
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* initializes variables that couldn't be statically initialized.
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*
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* This only exists for built-in code, not for modules.
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*/
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#define pure_initcall(fn) __define_initcall("0",fn,0)
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#define core_initcall(fn) __define_initcall("1",fn,1)
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#define core_initcall_sync(fn) __define_initcall("1s",fn,1s)
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#define postcore_initcall(fn) __define_initcall("2",fn,2)
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#define postcore_initcall_sync(fn) __define_initcall("2s",fn,2s)
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#define arch_initcall(fn) __define_initcall("3",fn,3)
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#define arch_initcall_sync(fn) __define_initcall("3s",fn,3s)
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#define subsys_initcall(fn) __define_initcall("4",fn,4)
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#define subsys_initcall_sync(fn) __define_initcall("4s",fn,4s)
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#define fs_initcall(fn) __define_initcall("5",fn,5)
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#define fs_initcall_sync(fn) __define_initcall("5s",fn,5s)
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#define rootfs_initcall(fn) __define_initcall("rootfs",fn,rootfs)
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#define device_initcall(fn) __define_initcall("6",fn,6)
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#define device_initcall_sync(fn) __define_initcall("6s",fn,6s)
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#define late_initcall(fn) __define_initcall("7",fn,7)
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#define late_initcall_sync(fn) __define_initcall("7s",fn,7s)
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#define __initcall(fn) device_initcall(fn)
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#define __exitcall(fn) \
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static exitcall_t __exitcall_##fn __exit_call = fn
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#define console_initcall(fn) \
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static initcall_t __initcall_##fn \
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__used __section(.con_initcall.init) = fn
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#define security_initcall(fn) \
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static initcall_t __initcall_##fn \
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__used __section(.security_initcall.init) = fn
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struct obs_kernel_param {
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const char *str;
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int (*setup_func)(char *);
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int early;
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};
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/*
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* Only for really core code. See moduleparam.h for the normal way.
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*
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* Force the alignment so the compiler doesn't space elements of the
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* obs_kernel_param "array" too far apart in .init.setup.
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*/
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#define __setup_param(str, unique_id, fn, early) \
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static const char __setup_str_##unique_id[] __initconst \
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__aligned(1) = str; \
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static struct obs_kernel_param __setup_##unique_id \
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__used __section(.init.setup) \
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__attribute__((aligned((sizeof(long))))) \
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= { __setup_str_##unique_id, fn, early }
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#define __setup(str, fn) \
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__setup_param(str, fn, fn, 0)
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/* NOTE: fn is as per module_param, not __setup! Emits warning if fn
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* returns non-zero. */
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#define early_param(str, fn) \
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__setup_param(str, fn, fn, 1)
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/* Relies on boot_command_line being set */
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void __init parse_early_param(void);
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void __init parse_early_options(char *cmdline);
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#endif /* __ASSEMBLY__ */
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/**
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* module_init() - driver initialization entry point
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* @x: function to be run at kernel boot time or module insertion
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*
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* module_init() will either be called during do_initcalls() (if
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* builtin) or at module insertion time (if a module). There can only
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* be one per module.
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*/
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#define module_init(x) __initcall(x);
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/**
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* module_exit() - driver exit entry point
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* @x: function to be run when driver is removed
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*
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* module_exit() will wrap the driver clean-up code
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* with cleanup_module() when used with rmmod when
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* the driver is a module. If the driver is statically
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* compiled into the kernel, module_exit() has no effect.
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* There can only be one per module.
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*/
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#define module_exit(x) __exitcall(x);
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#else /* MODULE */
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/* Don't use these in modules, but some people do... */
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#define early_initcall(fn) module_init(fn)
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#define core_initcall(fn) module_init(fn)
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#define postcore_initcall(fn) module_init(fn)
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#define arch_initcall(fn) module_init(fn)
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#define subsys_initcall(fn) module_init(fn)
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#define fs_initcall(fn) module_init(fn)
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#define device_initcall(fn) module_init(fn)
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#define late_initcall(fn) module_init(fn)
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#define security_initcall(fn) module_init(fn)
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/* Each module must use one module_init(). */
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#define module_init(initfn) \
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static inline initcall_t __inittest(void) \
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{ return initfn; } \
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int init_module(void) __attribute__((alias(#initfn)));
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/* This is only required if you want to be unloadable. */
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#define module_exit(exitfn) \
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static inline exitcall_t __exittest(void) \
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{ return exitfn; } \
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void cleanup_module(void) __attribute__((alias(#exitfn)));
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#define __setup_param(str, unique_id, fn) /* nothing */
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#define __setup(str, func) /* nothing */
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#endif
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/* Data marked not to be saved by software suspend */
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#define __nosavedata __section(.data..nosave)
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/* This means "can be init if no module support, otherwise module load
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may call it." */
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#ifdef CONFIG_MODULES
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#define __init_or_module
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#define __initdata_or_module
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#define __initconst_or_module
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#define __INIT_OR_MODULE .text
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#define __INITDATA_OR_MODULE .data
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#define __INITRODATA_OR_MODULE .section ".rodata","a",%progbits
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#else
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#define __init_or_module __init
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#define __initdata_or_module __initdata
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#define __initconst_or_module __initconst
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#define __INIT_OR_MODULE __INIT
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#define __INITDATA_OR_MODULE __INITDATA
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#define __INITRODATA_OR_MODULE __INITRODATA
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#endif /*CONFIG_MODULES*/
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/* Functions marked as __devexit may be discarded at kernel link time, depending
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on config options. Newer versions of binutils detect references from
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retained sections to discarded sections and flag an error. Pointers to
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__devexit functions must use __devexit_p(function_name), the wrapper will
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insert either the function_name or NULL, depending on the config options.
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*/
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#if defined(MODULE) || defined(CONFIG_HOTPLUG)
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#define __devexit_p(x) x
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#else
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#define __devexit_p(x) NULL
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#endif
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#ifdef MODULE
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#define __exit_p(x) x
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#else
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#define __exit_p(x) NULL
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#endif
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#endif /* _LINUX_INIT_H */
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