module.c 78.2 KB
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/*
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   Copyright (C) 2002 Richard Henderson
   Copyright (C) 2001 Rusty Russell, 2002 Rusty Russell IBM.

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/
#include <linux/module.h>
#include <linux/moduleloader.h>
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#include <linux/ftrace_event.h>
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#include <linux/init.h>
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#include <linux/kallsyms.h>
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#include <linux/fs.h>
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#include <linux/sysfs.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/elf.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
#include <linux/syscalls.h>
#include <linux/fcntl.h>
#include <linux/rcupdate.h>
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#include <linux/capability.h>
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#include <linux/cpu.h>
#include <linux/moduleparam.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/vermagic.h>
#include <linux/notifier.h>
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#include <linux/sched.h>
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#include <linux/stop_machine.h>
#include <linux/device.h>
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#include <linux/string.h>
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#include <linux/mutex.h>
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#include <linux/rculist.h>
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#include <asm/uaccess.h>
#include <asm/cacheflush.h>
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#include <asm/mmu_context.h>
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#include <linux/license.h>
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#include <asm/sections.h>
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#include <linux/tracepoint.h>
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#include <linux/ftrace.h>
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#include <linux/async.h>
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#include <linux/percpu.h>
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#include <linux/kmemleak.h>
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#define CREATE_TRACE_POINTS
#include <trace/events/module.h>

EXPORT_TRACEPOINT_SYMBOL(module_get);

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#if 0
#define DEBUGP printk
#else
#define DEBUGP(fmt , a...)
#endif

#ifndef ARCH_SHF_SMALL
#define ARCH_SHF_SMALL 0
#endif

/* If this is set, the section belongs in the init part of the module */
#define INIT_OFFSET_MASK (1UL << (BITS_PER_LONG-1))

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/* List of modules, protected by module_mutex or preempt_disable
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 * (delete uses stop_machine/add uses RCU list operations). */
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DEFINE_MUTEX(module_mutex);
EXPORT_SYMBOL_GPL(module_mutex);
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static LIST_HEAD(modules);

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/* Block module loading/unloading? */
int modules_disabled = 0;

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/* Waiting for a module to finish initializing? */
static DECLARE_WAIT_QUEUE_HEAD(module_wq);

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static BLOCKING_NOTIFIER_HEAD(module_notify_list);
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/* Bounds of module allocation, for speeding __module_address */
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static unsigned long module_addr_min = -1UL, module_addr_max = 0;

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int register_module_notifier(struct notifier_block * nb)
{
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	return blocking_notifier_chain_register(&module_notify_list, nb);
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}
EXPORT_SYMBOL(register_module_notifier);

int unregister_module_notifier(struct notifier_block * nb)
{
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	return blocking_notifier_chain_unregister(&module_notify_list, nb);
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}
EXPORT_SYMBOL(unregister_module_notifier);

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/* We require a truly strong try_module_get(): 0 means failure due to
   ongoing or failed initialization etc. */
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static inline int strong_try_module_get(struct module *mod)
{
	if (mod && mod->state == MODULE_STATE_COMING)
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		return -EBUSY;
	if (try_module_get(mod))
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		return 0;
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	else
		return -ENOENT;
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}

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static inline void add_taint_module(struct module *mod, unsigned flag)
{
	add_taint(flag);
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	mod->taints |= (1U << flag);
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}

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/*
 * A thread that wants to hold a reference to a module only while it
 * is running can call this to safely exit.  nfsd and lockd use this.
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 */
void __module_put_and_exit(struct module *mod, long code)
{
	module_put(mod);
	do_exit(code);
}
EXPORT_SYMBOL(__module_put_and_exit);
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/* Find a module section: 0 means not found. */
static unsigned int find_sec(Elf_Ehdr *hdr,
			     Elf_Shdr *sechdrs,
			     const char *secstrings,
			     const char *name)
{
	unsigned int i;

	for (i = 1; i < hdr->e_shnum; i++)
		/* Alloc bit cleared means "ignore it." */
		if ((sechdrs[i].sh_flags & SHF_ALLOC)
		    && strcmp(secstrings+sechdrs[i].sh_name, name) == 0)
			return i;
	return 0;
}

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/* Find a module section, or NULL. */
static void *section_addr(Elf_Ehdr *hdr, Elf_Shdr *shdrs,
			  const char *secstrings, const char *name)
{
	/* Section 0 has sh_addr 0. */
	return (void *)shdrs[find_sec(hdr, shdrs, secstrings, name)].sh_addr;
}

/* Find a module section, or NULL.  Fill in number of "objects" in section. */
static void *section_objs(Elf_Ehdr *hdr,
			  Elf_Shdr *sechdrs,
			  const char *secstrings,
			  const char *name,
			  size_t object_size,
			  unsigned int *num)
{
	unsigned int sec = find_sec(hdr, sechdrs, secstrings, name);

	/* Section 0 has sh_addr 0 and sh_size 0. */
	*num = sechdrs[sec].sh_size / object_size;
	return (void *)sechdrs[sec].sh_addr;
}

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/* Provided by the linker */
extern const struct kernel_symbol __start___ksymtab[];
extern const struct kernel_symbol __stop___ksymtab[];
extern const struct kernel_symbol __start___ksymtab_gpl[];
extern const struct kernel_symbol __stop___ksymtab_gpl[];
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extern const struct kernel_symbol __start___ksymtab_gpl_future[];
extern const struct kernel_symbol __stop___ksymtab_gpl_future[];
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extern const struct kernel_symbol __start___ksymtab_gpl_future[];
extern const struct kernel_symbol __stop___ksymtab_gpl_future[];
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extern const unsigned long __start___kcrctab[];
extern const unsigned long __start___kcrctab_gpl[];
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extern const unsigned long __start___kcrctab_gpl_future[];
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#ifdef CONFIG_UNUSED_SYMBOLS
extern const struct kernel_symbol __start___ksymtab_unused[];
extern const struct kernel_symbol __stop___ksymtab_unused[];
extern const struct kernel_symbol __start___ksymtab_unused_gpl[];
extern const struct kernel_symbol __stop___ksymtab_unused_gpl[];
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extern const unsigned long __start___kcrctab_unused[];
extern const unsigned long __start___kcrctab_unused_gpl[];
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#endif
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#ifndef CONFIG_MODVERSIONS
#define symversion(base, idx) NULL
#else
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#define symversion(base, idx) ((base != NULL) ? ((base) + (idx)) : NULL)
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#endif

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static bool each_symbol_in_section(const struct symsearch *arr,
				   unsigned int arrsize,
				   struct module *owner,
				   bool (*fn)(const struct symsearch *syms,
					      struct module *owner,
					      unsigned int symnum, void *data),
				   void *data)
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{
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	unsigned int i, j;
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	for (j = 0; j < arrsize; j++) {
		for (i = 0; i < arr[j].stop - arr[j].start; i++)
			if (fn(&arr[j], owner, i, data))
				return true;
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	}
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	return false;
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}

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/* Returns true as soon as fn returns true, otherwise false. */
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bool each_symbol(bool (*fn)(const struct symsearch *arr, struct module *owner,
			    unsigned int symnum, void *data), void *data)
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{
	struct module *mod;
	const struct symsearch arr[] = {
		{ __start___ksymtab, __stop___ksymtab, __start___kcrctab,
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		  NOT_GPL_ONLY, false },
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		{ __start___ksymtab_gpl, __stop___ksymtab_gpl,
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		  __start___kcrctab_gpl,
		  GPL_ONLY, false },
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		{ __start___ksymtab_gpl_future, __stop___ksymtab_gpl_future,
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		  __start___kcrctab_gpl_future,
		  WILL_BE_GPL_ONLY, false },
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#ifdef CONFIG_UNUSED_SYMBOLS
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		{ __start___ksymtab_unused, __stop___ksymtab_unused,
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		  __start___kcrctab_unused,
		  NOT_GPL_ONLY, true },
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		{ __start___ksymtab_unused_gpl, __stop___ksymtab_unused_gpl,
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		  __start___kcrctab_unused_gpl,
		  GPL_ONLY, true },
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#endif
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	};
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	if (each_symbol_in_section(arr, ARRAY_SIZE(arr), NULL, fn, data))
		return true;
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	list_for_each_entry_rcu(mod, &modules, list) {
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		struct symsearch arr[] = {
			{ mod->syms, mod->syms + mod->num_syms, mod->crcs,
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			  NOT_GPL_ONLY, false },
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			{ mod->gpl_syms, mod->gpl_syms + mod->num_gpl_syms,
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			  mod->gpl_crcs,
			  GPL_ONLY, false },
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			{ mod->gpl_future_syms,
			  mod->gpl_future_syms + mod->num_gpl_future_syms,
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			  mod->gpl_future_crcs,
			  WILL_BE_GPL_ONLY, false },
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#ifdef CONFIG_UNUSED_SYMBOLS
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			{ mod->unused_syms,
			  mod->unused_syms + mod->num_unused_syms,
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			  mod->unused_crcs,
			  NOT_GPL_ONLY, true },
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			{ mod->unused_gpl_syms,
			  mod->unused_gpl_syms + mod->num_unused_gpl_syms,
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			  mod->unused_gpl_crcs,
			  GPL_ONLY, true },
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#endif
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		};

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		if (each_symbol_in_section(arr, ARRAY_SIZE(arr), mod, fn, data))
			return true;
	}
	return false;
}
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EXPORT_SYMBOL_GPL(each_symbol);
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struct find_symbol_arg {
	/* Input */
	const char *name;
	bool gplok;
	bool warn;

	/* Output */
	struct module *owner;
	const unsigned long *crc;
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	const struct kernel_symbol *sym;
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};

static bool find_symbol_in_section(const struct symsearch *syms,
				   struct module *owner,
				   unsigned int symnum, void *data)
{
	struct find_symbol_arg *fsa = data;

	if (strcmp(syms->start[symnum].name, fsa->name) != 0)
		return false;

	if (!fsa->gplok) {
		if (syms->licence == GPL_ONLY)
			return false;
		if (syms->licence == WILL_BE_GPL_ONLY && fsa->warn) {
			printk(KERN_WARNING "Symbol %s is being used "
			       "by a non-GPL module, which will not "
			       "be allowed in the future\n", fsa->name);
			printk(KERN_WARNING "Please see the file "
			       "Documentation/feature-removal-schedule.txt "
			       "in the kernel source tree for more details.\n");
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		}
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	}
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#ifdef CONFIG_UNUSED_SYMBOLS
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	if (syms->unused && fsa->warn) {
		printk(KERN_WARNING "Symbol %s is marked as UNUSED, "
		       "however this module is using it.\n", fsa->name);
		printk(KERN_WARNING
		       "This symbol will go away in the future.\n");
		printk(KERN_WARNING
		       "Please evalute if this is the right api to use and if "
		       "it really is, submit a report the linux kernel "
		       "mailinglist together with submitting your code for "
		       "inclusion.\n");
	}
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#endif
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	fsa->owner = owner;
	fsa->crc = symversion(syms->crcs, symnum);
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	fsa->sym = &syms->start[symnum];
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	return true;
}

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/* Find a symbol and return it, along with, (optional) crc and
 * (optional) module which owns it */
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const struct kernel_symbol *find_symbol(const char *name,
					struct module **owner,
					const unsigned long **crc,
					bool gplok,
					bool warn)
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{
	struct find_symbol_arg fsa;

	fsa.name = name;
	fsa.gplok = gplok;
	fsa.warn = warn;

	if (each_symbol(find_symbol_in_section, &fsa)) {
		if (owner)
			*owner = fsa.owner;
		if (crc)
			*crc = fsa.crc;
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		return fsa.sym;
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	}

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	DEBUGP("Failed to find symbol %s\n", name);
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	return NULL;
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}
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EXPORT_SYMBOL_GPL(find_symbol);
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/* Search for module by name: must hold module_mutex. */
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struct module *find_module(const char *name)
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{
	struct module *mod;

	list_for_each_entry(mod, &modules, list) {
		if (strcmp(mod->name, name) == 0)
			return mod;
	}
	return NULL;
}
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EXPORT_SYMBOL_GPL(find_module);
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#ifdef CONFIG_SMP
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static inline void __percpu *mod_percpu(struct module *mod)
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{
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	return mod->percpu;
}
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static int percpu_modalloc(struct module *mod,
			   unsigned long size, unsigned long align)
{
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	if (align > PAGE_SIZE) {
		printk(KERN_WARNING "%s: per-cpu alignment %li > %li\n",
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		       mod->name, align, PAGE_SIZE);
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		align = PAGE_SIZE;
	}

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	mod->percpu = __alloc_reserved_percpu(size, align);
	if (!mod->percpu) {
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		printk(KERN_WARNING
		       "Could not allocate %lu bytes percpu data\n", size);
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		return -ENOMEM;
	}
	mod->percpu_size = size;
	return 0;
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}

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static void percpu_modfree(struct module *mod)
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{
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	free_percpu(mod->percpu);
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}

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static unsigned int find_pcpusec(Elf_Ehdr *hdr,
				 Elf_Shdr *sechdrs,
				 const char *secstrings)
{
	return find_sec(hdr, sechdrs, secstrings, ".data.percpu");
}

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static void percpu_modcopy(struct module *mod,
			   const void *from, unsigned long size)
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{
	int cpu;

	for_each_possible_cpu(cpu)
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		memcpy(per_cpu_ptr(mod->percpu, cpu), from, size);
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}

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/**
 * is_module_percpu_address - test whether address is from module static percpu
 * @addr: address to test
 *
 * Test whether @addr belongs to module static percpu area.
 *
 * RETURNS:
 * %true if @addr is from module static percpu area
 */
bool is_module_percpu_address(unsigned long addr)
{
	struct module *mod;
	unsigned int cpu;

	preempt_disable();

	list_for_each_entry_rcu(mod, &modules, list) {
		if (!mod->percpu_size)
			continue;
		for_each_possible_cpu(cpu) {
			void *start = per_cpu_ptr(mod->percpu, cpu);

			if ((void *)addr >= start &&
			    (void *)addr < start + mod->percpu_size) {
				preempt_enable();
				return true;
			}
		}
	}

	preempt_enable();
	return false;
}

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#else /* ... !CONFIG_SMP */
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static inline void __percpu *mod_percpu(struct module *mod)
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{
	return NULL;
}
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static inline int percpu_modalloc(struct module *mod,
				  unsigned long size, unsigned long align)
{
	return -ENOMEM;
}
static inline void percpu_modfree(struct module *mod)
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{
}
static inline unsigned int find_pcpusec(Elf_Ehdr *hdr,
					Elf_Shdr *sechdrs,
					const char *secstrings)
{
	return 0;
}
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static inline void percpu_modcopy(struct module *mod,
				  const void *from, unsigned long size)
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{
	/* pcpusec should be 0, and size of that section should be 0. */
	BUG_ON(size != 0);
}
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bool is_module_percpu_address(unsigned long addr)
{
	return false;
}
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#endif /* CONFIG_SMP */

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#define MODINFO_ATTR(field)	\
static void setup_modinfo_##field(struct module *mod, const char *s)  \
{                                                                     \
	mod->field = kstrdup(s, GFP_KERNEL);                          \
}                                                                     \
static ssize_t show_modinfo_##field(struct module_attribute *mattr,   \
	                struct module *mod, char *buffer)             \
{                                                                     \
	return sprintf(buffer, "%s\n", mod->field);                   \
}                                                                     \
static int modinfo_##field##_exists(struct module *mod)               \
{                                                                     \
	return mod->field != NULL;                                    \
}                                                                     \
static void free_modinfo_##field(struct module *mod)                  \
{                                                                     \
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	kfree(mod->field);                                            \
	mod->field = NULL;                                            \
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}                                                                     \
static struct module_attribute modinfo_##field = {                    \
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	.attr = { .name = __stringify(field), .mode = 0444 },         \
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	.show = show_modinfo_##field,                                 \
	.setup = setup_modinfo_##field,                               \
	.test = modinfo_##field##_exists,                             \
	.free = free_modinfo_##field,                                 \
};

MODINFO_ATTR(version);
MODINFO_ATTR(srcversion);

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static char last_unloaded_module[MODULE_NAME_LEN+1];

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#ifdef CONFIG_MODULE_UNLOAD
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/* Init the unload section of the module. */
static void module_unload_init(struct module *mod)
{
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	int cpu;
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	INIT_LIST_HEAD(&mod->modules_which_use_me);
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	for_each_possible_cpu(cpu)
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		per_cpu_ptr(mod->refptr, cpu)->count = 0;

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	/* Hold reference count during initialization. */
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	__this_cpu_write(mod->refptr->count, 1);
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	/* Backwards compatibility macros put refcount during init. */
	mod->waiter = current;
}

/* modules using other modules */
struct module_use
{
	struct list_head list;
	struct module *module_which_uses;
};

/* Does a already use b? */
static int already_uses(struct module *a, struct module *b)
{
	struct module_use *use;

	list_for_each_entry(use, &b->modules_which_use_me, list) {
		if (use->module_which_uses == a) {
			DEBUGP("%s uses %s!\n", a->name, b->name);
			return 1;
		}
	}
	DEBUGP("%s does not use %s!\n", a->name, b->name);
	return 0;
}

/* Module a uses b */
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int use_module(struct module *a, struct module *b)
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{
	struct module_use *use;
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	int no_warn, err;
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	if (b == NULL || already_uses(a, b)) return 1;

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	/* If we're interrupted or time out, we fail. */
	if (wait_event_interruptible_timeout(
		    module_wq, (err = strong_try_module_get(b)) != -EBUSY,
		    30 * HZ) <= 0) {
		printk("%s: gave up waiting for init of module %s.\n",
		       a->name, b->name);
		return 0;
	}

	/* If strong_try_module_get() returned a different error, we fail. */
	if (err)
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		return 0;

	DEBUGP("Allocating new usage for %s.\n", a->name);
	use = kmalloc(sizeof(*use), GFP_ATOMIC);
	if (!use) {
		printk("%s: out of memory loading\n", a->name);
		module_put(b);
		return 0;
	}

	use->module_which_uses = a;
	list_add(&use->list, &b->modules_which_use_me);
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	no_warn = sysfs_create_link(b->holders_dir, &a->mkobj.kobj, a->name);
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	return 1;
}
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EXPORT_SYMBOL_GPL(use_module);
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/* Clear the unload stuff of the module. */
static void module_unload_free(struct module *mod)
{
	struct module *i;

	list_for_each_entry(i, &modules, list) {
		struct module_use *use;

		list_for_each_entry(use, &i->modules_which_use_me, list) {
			if (use->module_which_uses == mod) {
				DEBUGP("%s unusing %s\n", mod->name, i->name);
				module_put(i);
				list_del(&use->list);
				kfree(use);
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				sysfs_remove_link(i->holders_dir, mod->name);
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				/* There can be at most one match. */
				break;
			}
		}
	}
}

#ifdef CONFIG_MODULE_FORCE_UNLOAD
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static inline int try_force_unload(unsigned int flags)
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{
	int ret = (flags & O_TRUNC);
	if (ret)
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		add_taint(TAINT_FORCED_RMMOD);
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	return ret;
}
#else
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static inline int try_force_unload(unsigned int flags)
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{
	return 0;
}
#endif /* CONFIG_MODULE_FORCE_UNLOAD */

struct stopref
{
	struct module *mod;
	int flags;
	int *forced;
};

/* Whole machine is stopped with interrupts off when this runs. */
static int __try_stop_module(void *_sref)
{
	struct stopref *sref = _sref;

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	/* If it's not unused, quit unless we're forcing. */
	if (module_refcount(sref->mod) != 0) {
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		if (!(*sref->forced = try_force_unload(sref->flags)))
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			return -EWOULDBLOCK;
	}

	/* Mark it as dying. */
	sref->mod->state = MODULE_STATE_GOING;
	return 0;
}

static int try_stop_module(struct module *mod, int flags, int *forced)
{
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	if (flags & O_NONBLOCK) {
		struct stopref sref = { mod, flags, forced };
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		return stop_machine(__try_stop_module, &sref, NULL);
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	} else {
		/* We don't need to stop the machine for this. */
		mod->state = MODULE_STATE_GOING;
		synchronize_sched();
		return 0;
	}
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}

unsigned int module_refcount(struct module *mod)
{
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	unsigned int total = 0;
	int cpu;
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	for_each_possible_cpu(cpu)
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		total += per_cpu_ptr(mod->refptr, cpu)->count;
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	return total;
}
EXPORT_SYMBOL(module_refcount);

/* This exists whether we can unload or not */
static void free_module(struct module *mod);

static void wait_for_zero_refcount(struct module *mod)
{
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	/* Since we might sleep for some time, release the mutex first */
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	mutex_unlock(&module_mutex);
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	for (;;) {
		DEBUGP("Looking at refcount...\n");
		set_current_state(TASK_UNINTERRUPTIBLE);
		if (module_refcount(mod) == 0)
			break;
		schedule();
	}
	current->state = TASK_RUNNING;
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	mutex_lock(&module_mutex);
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}

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SYSCALL_DEFINE2(delete_module, const char __user *, name_user,
		unsigned int, flags)
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{
	struct module *mod;
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	char name[MODULE_NAME_LEN];
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	int ret, forced = 0;

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	if (!capable(CAP_SYS_MODULE) || modules_disabled)
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		return -EPERM;

	if (strncpy_from_user(name, name_user, MODULE_NAME_LEN-1) < 0)
		return -EFAULT;
	name[MODULE_NAME_LEN-1] = '\0';

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	/* Create stop_machine threads since free_module relies on
	 * a non-failing stop_machine call. */
	ret = stop_machine_create();
	if (ret)
		return ret;

	if (mutex_lock_interruptible(&module_mutex) != 0) {
		ret = -EINTR;
		goto out_stop;
	}
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	mod = find_module(name);
	if (!mod) {
		ret = -ENOENT;
		goto out;
	}

	if (!list_empty(&mod->modules_which_use_me)) {
		/* Other modules depend on us: get rid of them first. */
		ret = -EWOULDBLOCK;
		goto out;
	}

	/* Doing init or already dying? */
	if (mod->state != MODULE_STATE_LIVE) {
		/* FIXME: if (force), slam module count and wake up
                   waiter --RR */
		DEBUGP("%s already dying\n", mod->name);
		ret = -EBUSY;
		goto out;
	}

	/* If it has an init func, it must have an exit func to unload */
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	if (mod->init && !mod->exit) {
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		forced = try_force_unload(flags);
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		if (!forced) {
			/* This module can't be removed */
			ret = -EBUSY;
			goto out;
		}
	}

	/* Set this up before setting mod->state */
	mod->waiter = current;

	/* Stop the machine so refcounts can't move and disable module. */
	ret = try_stop_module(mod, flags, &forced);
	if (ret != 0)
		goto out;

	/* Never wait if forced. */
	if (!forced && module_refcount(mod) != 0)
		wait_for_zero_refcount(mod);

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	mutex_unlock(&module_mutex);
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	/* Final destruction now noone is using it. */
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	if (mod->exit != NULL)
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		mod->exit();
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	blocking_notifier_call_chain(&module_notify_list,
				     MODULE_STATE_GOING, mod);
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	async_synchronize_full();
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	mutex_lock(&module_mutex);
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	/* Store the name of the last unloaded module for diagnostic purposes */
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	strlcpy(last_unloaded_module, mod->name, sizeof(last_unloaded_module));
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	ddebug_remove_module(mod->name);
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	free_module(mod);

 out:
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	mutex_unlock(&module_mutex);
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out_stop:
	stop_machine_destroy();
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	return ret;
}

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static inline void print_unload_info(struct seq_file *m, struct module *mod)
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{
	struct module_use *use;
	int printed_something = 0;

	seq_printf(m, " %u ", module_refcount(mod));

	/* Always include a trailing , so userspace can differentiate
           between this and the old multi-field proc format. */
	list_for_each_entry(use, &mod->modules_which_use_me, list) {
		printed_something = 1;
		seq_printf(m, "%s,", use->module_which_uses->name);
	}

	if (mod->init != NULL && mod->exit == NULL) {
		printed_something = 1;
		seq_printf(m, "[permanent],");
	}

	if (!printed_something)
		seq_printf(m, "-");
}

void __symbol_put(const char *symbol)
{
	struct module *owner;

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	preempt_disable();
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	if (!find_symbol(symbol, &owner, NULL, true, false))
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		BUG();
	module_put(owner);
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	preempt_enable();
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}
EXPORT_SYMBOL(__symbol_put);

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/* Note this assumes addr is a function, which it currently always is. */
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void symbol_put_addr(void *addr)
{
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	struct module *modaddr;
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	unsigned long a = (unsigned long)dereference_function_descriptor(addr);
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	if (core_kernel_text(a))
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		return;
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	/* module_text_address is safe here: we're supposed to have reference
	 * to module from symbol_get, so it can't go away. */
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	modaddr = __module_text_address(a);
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	BUG_ON(!modaddr);
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	module_put(modaddr);
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}
EXPORT_SYMBOL_GPL(symbol_put_addr);

static ssize_t show_refcnt(struct module_attribute *mattr,
			   struct module *mod, char *buffer)
{
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	return sprintf(buffer, "%u\n", module_refcount(mod));
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}

static struct module_attribute refcnt = {
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	.attr = { .name = "refcnt", .mode = 0444 },
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	.show = show_refcnt,
};

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void module_put(struct module *module)
{
	if (module) {
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		preempt_disable();
		__this_cpu_dec(module->refptr->count);

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		trace_module_put(module, _RET_IP_,
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				 __this_cpu_read(module->refptr->count));
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		/* Maybe they're waiting for us to drop reference? */
		if (unlikely(!module_is_live(module)))
			wake_up_process(module->waiter);
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		preempt_enable();
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	}
}
EXPORT_SYMBOL(module_put);

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#else /* !CONFIG_MODULE_UNLOAD */
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static inline void print_unload_info(struct seq_file *m, struct module *mod)
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{
	/* We don't know the usage count, or what modules are using. */
	seq_printf(m, " - -");
}

static inline void module_unload_free(struct module *mod)
{
}

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int use_module(struct module *a, struct module *b)
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{
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	return strong_try_module_get(b) == 0;
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}
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EXPORT_SYMBOL_GPL(use_module);
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static inline void module_unload_init(struct module *mod)
{
}
#endif /* CONFIG_MODULE_UNLOAD */

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static ssize_t show_initstate(struct module_attribute *mattr,
			   struct module *mod, char *buffer)
{
	const char *state = "unknown";

	switch (mod->state) {
	case MODULE_STATE_LIVE:
		state = "live";
		break;
	case MODULE_STATE_COMING:
		state = "coming";
		break;
	case MODULE_STATE_GOING:
		state = "going";
		break;
	}
	return sprintf(buffer, "%s\n", state);
}

static struct module_attribute initstate = {
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	.attr = { .name = "initstate", .mode = 0444 },
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	.show = show_initstate,
};

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static struct module_attribute *modinfo_attrs[] = {
	&modinfo_version,
	&modinfo_srcversion,
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	&initstate,
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#ifdef CONFIG_MODULE_UNLOAD
	&refcnt,
#endif
	NULL,
};

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static const char vermagic[] = VERMAGIC_STRING;

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static int try_to_force_load(struct module *mod, const char *reason)
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{
#ifdef CONFIG_MODULE_FORCE_LOAD
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	if (!test_taint(TAINT_FORCED_MODULE))
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		printk(KERN_WARNING "%s: %s: kernel tainted.\n",
		       mod->name, reason);
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	add_taint_module(mod, TAINT_FORCED_MODULE);
	return 0;
#else
	return -ENOEXEC;
#endif
}

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#ifdef CONFIG_MODVERSIONS
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/* If the arch applies (non-zero) relocations to kernel kcrctab, unapply it. */
static unsigned long maybe_relocated(unsigned long crc,
				     const struct module *crc_owner)
{
#ifdef ARCH_RELOCATES_KCRCTAB
	if (crc_owner == NULL)
		return crc - (unsigned long)reloc_start;
#endif
	return crc;
}

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static int check_version(Elf_Shdr *sechdrs,
			 unsigned int versindex,
			 const char *symname,
			 struct module *mod, 
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			 const unsigned long *crc,
			 const struct module *crc_owner)
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{
	unsigned int i, num_versions;
	struct modversion_info *versions;

	/* Exporting module didn't supply crcs?  OK, we're already tainted. */
	if (!crc)
		return 1;

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	/* No versions at all?  modprobe --force does this. */
	if (versindex == 0)
		return try_to_force_load(mod, symname) == 0;

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	versions = (void *) sechdrs[versindex].sh_addr;
	num_versions = sechdrs[versindex].sh_size
		/ sizeof(struct modversion_info);

	for (i = 0; i < num_versions; i++) {
		if (strcmp(versions[i].name, symname) != 0)
			continue;

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		if (versions[i].crc == maybe_relocated(*crc, crc_owner))
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			return 1;
		DEBUGP("Found checksum %lX vs module %lX\n",
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		       maybe_relocated(*crc, crc_owner), versions[i].crc);
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		goto bad_version;
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	}
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	printk(KERN_WARNING "%s: no symbol version for %s\n",
	       mod->name, symname);
	return 0;
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bad_version:
	printk("%s: disagrees about version of symbol %s\n",
	       mod->name, symname);
	return 0;
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}

static inline int check_modstruct_version(Elf_Shdr *sechdrs,
					  unsigned int versindex,
					  struct module *mod)
{
	const unsigned long *crc;

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	if (!find_symbol(MODULE_SYMBOL_PREFIX "module_layout", NULL,
			 &crc, true, false))
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		BUG();
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	return check_version(sechdrs, versindex, "module_layout", mod, crc,
			     NULL);
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}

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/* First part is kernel version, which we ignore if module has crcs. */
static inline int same_magic(const char *amagic, const char *bmagic,
			     bool has_crcs)
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{
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	if (has_crcs) {
		amagic += strcspn(amagic, " ");
		bmagic += strcspn(bmagic, " ");
	}
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	return strcmp(amagic, bmagic) == 0;
}
#else
static inline int check_version(Elf_Shdr *sechdrs,
				unsigned int versindex,
				const char *symname,
				struct module *mod, 
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				const unsigned long *crc,
				const struct module *crc_owner)
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{
	return 1;
}

static inline int check_modstruct_version(Elf_Shdr *sechdrs,
					  unsigned int versindex,
					  struct module *mod)
{
	return 1;
}

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static inline int same_magic(const char *amagic, const char *bmagic,
			     bool has_crcs)
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{
	return strcmp(amagic, bmagic) == 0;
}
#endif /* CONFIG_MODVERSIONS */

/* Resolve a symbol for this module.  I.e. if we find one, record usage.
   Must be holding module_mutex. */
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static const struct kernel_symbol *resolve_symbol(Elf_Shdr *sechdrs,
						  unsigned int versindex,
						  const char *name,
						  struct module *mod)
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{
	struct module *owner;
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	const struct kernel_symbol *sym;
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	const unsigned long *crc;

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	sym = find_symbol(name, &owner, &crc,
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			  !(mod->taints & (1 << TAINT_PROPRIETARY_MODULE)), true);
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	/* use_module can fail due to OOM,
	   or module initialization or unloading */
	if (sym) {
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		if (!check_version(sechdrs, versindex, name, mod, crc, owner)
		    || !use_module(mod, owner))
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			sym = NULL;
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	}
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	return sym;
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}

/*
 * /sys/module/foo/sections stuff
 * J. Corbet <corbet@lwn.net>
 */
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#if defined(CONFIG_KALLSYMS) && defined(CONFIG_SYSFS)
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static inline bool sect_empty(const Elf_Shdr *sect)
{
	return !(sect->sh_flags & SHF_ALLOC) || sect->sh_size == 0;
}

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struct module_sect_attr
{
	struct module_attribute mattr;
	char *name;
	unsigned long address;
};

struct module_sect_attrs
{
	struct attribute_group grp;
	unsigned int nsections;
	struct module_sect_attr attrs[0];
};

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static ssize_t module_sect_show(struct module_attribute *mattr,
				struct module *mod, char *buf)
{
	struct module_sect_attr *sattr =
		container_of(mattr, struct module_sect_attr, mattr);
	return sprintf(buf, "0x%lx\n", sattr->address);
}

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static void free_sect_attrs(struct module_sect_attrs *sect_attrs)
{
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	unsigned int section;
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	for (section = 0; section < sect_attrs->nsections; section++)
		kfree(sect_attrs->attrs[section].name);
	kfree(sect_attrs);
}

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static void add_sect_attrs(struct module *mod, unsigned int nsect,
		char *secstrings, Elf_Shdr *sechdrs)
{
	unsigned int nloaded = 0, i, size[2];
	struct module_sect_attrs *sect_attrs;
	struct module_sect_attr *sattr;
	struct attribute **gattr;
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	/* Count loaded sections and allocate structures */
	for (i = 0; i < nsect; i++)
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		if (!sect_empty(&sechdrs[i]))
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			nloaded++;
	size[0] = ALIGN(sizeof(*sect_attrs)
			+ nloaded * sizeof(sect_attrs->attrs[0]),
			sizeof(sect_attrs->grp.attrs[0]));
	size[1] = (nloaded + 1) * sizeof(sect_attrs->grp.attrs[0]);
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	sect_attrs = kzalloc(size[0] + size[1], GFP_KERNEL);
	if (sect_attrs == NULL)
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		return;

	/* Setup section attributes. */
	sect_attrs->grp.name = "sections";
	sect_attrs->grp.attrs = (void *)sect_attrs + size[0];

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	sect_attrs->nsections = 0;
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	sattr = &sect_attrs->attrs[0];
	gattr = &sect_attrs->grp.attrs[0];
	for (i = 0; i < nsect; i++) {
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		if (sect_empty(&sechdrs[i]))
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			continue;
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		sattr->address = sechdrs[i].sh_addr;
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		sattr->name = kstrdup(secstrings + sechdrs[i].sh_name,
					GFP_KERNEL);
		if (sattr->name == NULL)
			goto out;
		sect_attrs->nsections++;
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		sysfs_attr_init(&sattr->mattr.attr);
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		sattr->mattr.show = module_sect_show;
		sattr->mattr.store = NULL;
		sattr->mattr.attr.name = sattr->name;
		sattr->mattr.attr.mode = S_IRUGO;
		*(gattr++) = &(sattr++)->mattr.attr;
	}
	*gattr = NULL;

	if (sysfs_create_group(&mod->mkobj.kobj, &sect_attrs->grp))
		goto out;

	mod->sect_attrs = sect_attrs;
	return;
  out:
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	free_sect_attrs(sect_attrs);
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}

static void remove_sect_attrs(struct module *mod)
{
	if (mod->sect_attrs) {
		sysfs_remove_group(&mod->mkobj.kobj,
				   &mod->sect_attrs->grp);
		/* We are positive that no one is using any sect attrs
		 * at this point.  Deallocate immediately. */
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		free_sect_attrs(mod->sect_attrs);
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		mod->sect_attrs = NULL;
	}
}

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/*
 * /sys/module/foo/notes/.section.name gives contents of SHT_NOTE sections.
 */

struct module_notes_attrs {
	struct kobject *dir;
	unsigned int notes;
	struct bin_attribute attrs[0];
};

static ssize_t module_notes_read(struct kobject *kobj,
				 struct bin_attribute *bin_attr,
				 char *buf, loff_t pos, size_t count)
{
	/*
	 * The caller checked the pos and count against our size.
	 */
	memcpy(buf, bin_attr->private + pos, count);
	return count;
}

static void free_notes_attrs(struct module_notes_attrs *notes_attrs,
			     unsigned int i)
{
	if (notes_attrs->dir) {
		while (i-- > 0)
			sysfs_remove_bin_file(notes_attrs->dir,
					      &notes_attrs->attrs[i]);
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		kobject_put(notes_attrs->dir);
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	}
	kfree(notes_attrs);
}

static void add_notes_attrs(struct module *mod, unsigned int nsect,
			    char *secstrings, Elf_Shdr *sechdrs)
{
	unsigned int notes, loaded, i;
	struct module_notes_attrs *notes_attrs;
	struct bin_attribute *nattr;

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	/* failed to create section attributes, so can't create notes */
	if (!mod->sect_attrs)
		return;

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	/* Count notes sections and allocate structures.  */
	notes = 0;
	for (i = 0; i < nsect; i++)
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		if (!sect_empty(&sechdrs[i]) &&
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		    (sechdrs[i].sh_type == SHT_NOTE))
			++notes;

	if (notes == 0)
		return;

	notes_attrs = kzalloc(sizeof(*notes_attrs)
			      + notes * sizeof(notes_attrs->attrs[0]),
			      GFP_KERNEL);
	if (notes_attrs == NULL)
		return;

	notes_attrs->notes = notes;
	nattr = &notes_attrs->attrs[0];
	for (loaded = i = 0; i < nsect; ++i) {
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		if (sect_empty(&sechdrs[i]))
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			continue;
		if (sechdrs[i].sh_type == SHT_NOTE) {
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			sysfs_bin_attr_init(nattr);
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			nattr->attr.name = mod->sect_attrs->attrs[loaded].name;
			nattr->attr.mode = S_IRUGO;
			nattr->size = sechdrs[i].sh_size;
			nattr->private = (void *) sechdrs[i].sh_addr;
			nattr->read = module_notes_read;
			++nattr;
		}
		++loaded;
	}

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	notes_attrs->dir = kobject_create_and_add("notes", &mod->mkobj.kobj);
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	if (!notes_attrs->dir)
		goto out;

	for (i = 0; i < notes; ++i)
		if (sysfs_create_bin_file(notes_attrs->dir,
					  &notes_attrs->attrs[i]))
			goto out;

	mod->notes_attrs = notes_attrs;
	return;

  out:
	free_notes_attrs(notes_attrs, i);
}

static void remove_notes_attrs(struct module *mod)
{
	if (mod->notes_attrs)
		free_notes_attrs(mod->notes_attrs, mod->notes_attrs->notes);
}

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#else
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static inline void add_sect_attrs(struct module *mod, unsigned int nsect,
		char *sectstrings, Elf_Shdr *sechdrs)
{
}

static inline void remove_sect_attrs(struct module *mod)
{
}
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static inline void add_notes_attrs(struct module *mod, unsigned int nsect,
				   char *sectstrings, Elf_Shdr *sechdrs)
{
}

static inline void remove_notes_attrs(struct module *mod)
{
}
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#endif
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#ifdef CONFIG_SYSFS
int module_add_modinfo_attrs(struct module *mod)
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{
	struct module_attribute *attr;
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	struct module_attribute *temp_attr;
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	int error = 0;
	int i;

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	mod->modinfo_attrs = kzalloc((sizeof(struct module_attribute) *
					(ARRAY_SIZE(modinfo_attrs) + 1)),
					GFP_KERNEL);
	if (!mod->modinfo_attrs)
		return -ENOMEM;

	temp_attr = mod->modinfo_attrs;
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	for (i = 0; (attr = modinfo_attrs[i]) && !error; i++) {
		if (!attr->test ||
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		    (attr->test && attr->test(mod))) {
			memcpy(temp_attr, attr, sizeof(*temp_attr));
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			sysfs_attr_init(&temp_attr->attr);
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			error = sysfs_create_file(&mod->mkobj.kobj,&temp_attr->attr);
			++temp_attr;
		}
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	}
	return error;
}

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void module_remove_modinfo_attrs(struct module *mod)
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{
	struct module_attribute *attr;
	int i;

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	for (i = 0; (attr = &mod->modinfo_attrs[i]); i++) {
		/* pick a field to test for end of list */
		if (!attr->attr.name)
			break;
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		sysfs_remove_file(&mod->mkobj.kobj,&attr->attr);
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		if (attr->free)
			attr->free(mod);
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	}
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	kfree(mod->modinfo_attrs);
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}
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int mod_sysfs_init(struct module *mod)
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{
	int err;
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	struct kobject *kobj;
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	if (!module_sysfs_initialized) {
		printk(KERN_ERR "%s: module sysfs not initialized\n",
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		       mod->name);
		err = -EINVAL;
		goto out;
	}
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	kobj = kset_find_obj(module_kset, mod->name);
	if (kobj) {
		printk(KERN_ERR "%s: module is already loaded\n", mod->name);
		kobject_put(kobj);
		err = -EINVAL;
		goto out;
	}

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	mod->mkobj.mod = mod;
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	memset(&mod->mkobj.kobj, 0, sizeof(mod->mkobj.kobj));
	mod->mkobj.kobj.kset = module_kset;
	err = kobject_init_and_add(&mod->mkobj.kobj, &module_ktype, NULL,
				   "%s", mod->name);
	if (err)
		kobject_put(&mod->mkobj.kobj);
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	/* delay uevent until full sysfs population */
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out:
	return err;
}

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int mod_sysfs_setup(struct module *mod,
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			   struct kernel_param *kparam,
			   unsigned int num_params)
{
	int err;

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	mod->holders_dir = kobject_create_and_add("holders", &mod->mkobj.kobj);
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	if (!mod->holders_dir) {
		err = -ENOMEM;
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		goto out_unreg;
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	}
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	err = module_param_sysfs_setup(mod, kparam, num_params);
	if (err)
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		goto out_unreg_holders;
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	err = module_add_modinfo_attrs(mod);
	if (err)
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		goto out_unreg_param;