[net-next-2.6.git] / kernel / kmod.c

/*
	kmod, the new module loader (replaces kerneld)
	Kirk Petersen

	Reorganized not to be a daemon by Adam Richter, with guidance
	from Greg Zornetzer.

	Modified to avoid chroot and file sharing problems.
	Mikael Pettersson

	Limit the concurrent number of kmod modprobes to catch loops from
	"modprobe needs a service that is in a module".
	Keith Owens <kaos@ocs.com.au> December 1999

	Unblock all signals when we exec a usermode process.
	Shuu Yamaguchi <shuu@wondernetworkresources.com> December 2000

	call_usermodehelper wait flag, and remove exec_usermodehelper.
	Rusty Russell <rusty@rustcorp.com.au>  Jan 2003
*/
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/syscalls.h>
#include <linux/unistd.h>
#include <linux/kmod.h>
#include <linux/slab.h>
#include <linux/mnt_namespace.h>
#include <linux/completion.h>
#include <linux/file.h>
#include <linux/workqueue.h>
#include <linux/security.h>
#include <linux/mount.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/resource.h>
#include <asm/uaccess.h>

extern int max_threads;

static struct workqueue_struct *khelper_wq;

#ifdef CONFIG_KMOD

/*
	modprobe_path is set via /proc/sys.
*/
char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";

/**
 * request_module - try to load a kernel module
 * @fmt:     printf style format string for the name of the module
 * @varargs: arguements as specified in the format string
 *
 * Load a module using the user mode module loader. The function returns
 * zero on success or a negative errno code on failure. Note that a
 * successful module load does not mean the module did not then unload
 * and exit on an error of its own. Callers must check that the service
 * they requested is now available not blindly invoke it.
 *
 * If module auto-loading support is disabled then this function
 * becomes a no-operation.
 */
int request_module(const char *fmt, ...)
{
	va_list args;
	char module_name[MODULE_NAME_LEN];
	unsigned int max_modprobes;
	int ret;
	char *argv[] = { modprobe_path, "-q", "--", module_name, NULL };
	static char *envp[] = { "HOME=/",
				"TERM=linux",
				"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
				NULL };
	static atomic_t kmod_concurrent = ATOMIC_INIT(0);
#define MAX_KMOD_CONCURRENT 50	/* Completely arbitrary value - KAO */
	static int kmod_loop_msg;

	va_start(args, fmt);
	ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
	va_end(args);
	if (ret >= MODULE_NAME_LEN)
		return -ENAMETOOLONG;

	/* If modprobe needs a service that is in a module, we get a recursive
	 * loop.  Limit the number of running kmod threads to max_threads/2 or
	 * MAX_KMOD_CONCURRENT, whichever is the smaller.  A cleaner method
	 * would be to run the parents of this process, counting how many times
	 * kmod was invoked.  That would mean accessing the internals of the
	 * process tables to get the command line, proc_pid_cmdline is static
	 * and it is not worth changing the proc code just to handle this case. 
	 * KAO.
	 *
	 * "trace the ppid" is simple, but will fail if someone's
	 * parent exits.  I think this is as good as it gets. --RR
	 */
	max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
	atomic_inc(&kmod_concurrent);
	if (atomic_read(&kmod_concurrent) > max_modprobes) {
		/* We may be blaming an innocent here, but unlikely */
		if (kmod_loop_msg++ < 5)
			printk(KERN_ERR
			       "request_module: runaway loop modprobe %s\n",
			       module_name);
		atomic_dec(&kmod_concurrent);
		return -ENOMEM;
	}

	ret = call_usermodehelper(modprobe_path, argv, envp, 1);
	atomic_dec(&kmod_concurrent);
	return ret;
}
EXPORT_SYMBOL(request_module);
#endif /* CONFIG_KMOD */

struct subprocess_info {
	struct work_struct work;
	struct completion *complete;
	char *path;
	char **argv;
	char **envp;
	struct key *ring;
	int wait;
	int retval;
	struct file *stdin;
};

/*
 * This is the task which runs the usermode application
 */
static int ____call_usermodehelper(void *data)
{
	struct subprocess_info *sub_info = data;
	struct key *new_session, *old_session;
	int retval;

	/* Unblock all signals and set the session keyring. */
	new_session = key_get(sub_info->ring);
	spin_lock_irq(&current->sighand->siglock);
	old_session = __install_session_keyring(current, new_session);
	flush_signal_handlers(current, 1);
	sigemptyset(&current->blocked);
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);

	key_put(old_session);

	/* Install input pipe when needed */
	if (sub_info->stdin) {
		struct files_struct *f = current->files;
		struct fdtable *fdt;
		/* no races because files should be private here */
		sys_close(0);
		fd_install(0, sub_info->stdin);
		spin_lock(&f->file_lock);
		fdt = files_fdtable(f);
		FD_SET(0, fdt->open_fds);
		FD_CLR(0, fdt->close_on_exec);
		spin_unlock(&f->file_lock);

		/* and disallow core files too */
		current->signal->rlim[RLIMIT_CORE] = (struct rlimit){0, 0};
	}

	/* We can run anywhere, unlike our parent keventd(). */
	set_cpus_allowed(current, CPU_MASK_ALL);

	/*
	 * Our parent is keventd, which runs with elevated scheduling priority.
	 * Avoid propagating that into the userspace child.
	 */
	set_user_nice(current, 0);

	retval = -EPERM;
	if (current->fs->root)
		retval = kernel_execve(sub_info->path,
				sub_info->argv, sub_info->envp);

	/* Exec failed? */
	sub_info->retval = retval;
	do_exit(0);
}

/* Keventd can't block, but this (a child) can. */
static int wait_for_helper(void *data)
{
	struct subprocess_info *sub_info = data;
	pid_t pid;

	/* Install a handler: if SIGCLD isn't handled sys_wait4 won't
	 * populate the status, but will return -ECHILD. */
	allow_signal(SIGCHLD);

	pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD);
	if (pid < 0) {
		sub_info->retval = pid;
	} else {
		int ret;

		/*
		 * Normally it is bogus to call wait4() from in-kernel because
		 * wait4() wants to write the exit code to a userspace address.
		 * But wait_for_helper() always runs as keventd, and put_user()
		 * to a kernel address works OK for kernel threads, due to their
		 * having an mm_segment_t which spans the entire address space.
		 *
		 * Thus the __user pointer cast is valid here.
		 */
		sys_wait4(pid, (int __user *)&ret, 0, NULL);

		/*
		 * If ret is 0, either ____call_usermodehelper failed and the
		 * real error code is already in sub_info->retval or
		 * sub_info->retval is 0 anyway, so don't mess with it then.
		 */
		if (ret)
			sub_info->retval = ret;
	}

	if (sub_info->wait < 0)
		kfree(sub_info);
	else
		complete(sub_info->complete);
	return 0;
}

/* This is run by khelper thread  */
static void __call_usermodehelper(struct work_struct *work)
{
	struct subprocess_info *sub_info =
		container_of(work, struct subprocess_info, work);
	pid_t pid;
	int wait = sub_info->wait;

	/* CLONE_VFORK: wait until the usermode helper has execve'd
	 * successfully We need the data structures to stay around
	 * until that is done.  */
	if (wait)
		pid = kernel_thread(wait_for_helper, sub_info,
				    CLONE_FS | CLONE_FILES | SIGCHLD);
	else
		pid = kernel_thread(____call_usermodehelper, sub_info,
				    CLONE_VFORK | SIGCHLD);

	if (wait < 0)
		return;

	if (pid < 0) {
		sub_info->retval = pid;
		complete(sub_info->complete);
	} else if (!wait)
		complete(sub_info->complete);
}

/**
 * call_usermodehelper_keys - start a usermode application
 * @path: pathname for the application
 * @argv: null-terminated argument list
 * @envp: null-terminated environment list
 * @session_keyring: session keyring for process (NULL for an empty keyring)
 * @wait: wait for the application to finish and return status.
 *        when -1 don't wait at all, but you get no useful error back when
 *        the program couldn't be exec'ed. This makes it safe to call
 *        from interrupt context.
 *
 * Runs a user-space application.  The application is started
 * asynchronously if wait is not set, and runs as a child of keventd.
 * (ie. it runs with full root capabilities).
 *
 * Must be called from process context.  Returns a negative error code
 * if program was not execed successfully, or 0.
 */
int call_usermodehelper_keys(char *path, char **argv, char **envp,
			     struct key *session_keyring, int wait)
{
	DECLARE_COMPLETION_ONSTACK(done);
	struct subprocess_info *sub_info;
	int retval;

	if (!khelper_wq)
		return -EBUSY;

	if (path[0] == '\0')
		return 0;

	sub_info = kzalloc(sizeof(struct subprocess_info),  GFP_ATOMIC);
	if (!sub_info)
		return -ENOMEM;

	INIT_WORK(&sub_info->work, __call_usermodehelper);
	sub_info->complete = &done;
	sub_info->path = path;
	sub_info->argv = argv;
	sub_info->envp = envp;
	sub_info->ring = session_keyring;
	sub_info->wait = wait;

	queue_work(khelper_wq, &sub_info->work);
	if (wait < 0) /* task has freed sub_info */
		return 0;
	wait_for_completion(&done);
	retval = sub_info->retval;
	kfree(sub_info);
	return retval;
}
EXPORT_SYMBOL(call_usermodehelper_keys);

int call_usermodehelper_pipe(char *path, char **argv, char **envp,
			     struct file **filp)
{
	DECLARE_COMPLETION(done);
	struct subprocess_info sub_info = {
		.work		= __WORK_INITIALIZER(sub_info.work,
						     __call_usermodehelper),
		.complete	= &done,
		.path		= path,
		.argv		= argv,
		.envp		= envp,
		.retval		= 0,
	};
	struct file *f;

	if (!khelper_wq)
		return -EBUSY;

	if (path[0] == '\0')
		return 0;

	f = create_write_pipe();
	if (IS_ERR(f))
		return PTR_ERR(f);
	*filp = f;

	f = create_read_pipe(f);
	if (IS_ERR(f)) {
		free_write_pipe(*filp);
		return PTR_ERR(f);
	}
	sub_info.stdin = f;

	queue_work(khelper_wq, &sub_info.work);
	wait_for_completion(&done);
	return sub_info.retval;
}
EXPORT_SYMBOL(call_usermodehelper_pipe);

void __init usermodehelper_init(void)
{
	khelper_wq = create_singlethread_workqueue("khelper");
	BUG_ON(!khelper_wq);
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	kmod, the new module loader (replaces kerneld)
	3	Kirk Petersen
	4
	5	Reorganized not to be a daemon by Adam Richter, with guidance
	6	from Greg Zornetzer.
	7
	8	Modified to avoid chroot and file sharing problems.
	9	Mikael Pettersson
	10
	11	Limit the concurrent number of kmod modprobes to catch loops from
	12	"modprobe needs a service that is in a module".
	13	Keith Owens <kaos@ocs.com.au> December 1999
	14
	15	Unblock all signals when we exec a usermode process.
	16	Shuu Yamaguchi <shuu@wondernetworkresources.com> December 2000
	17
	18	call_usermodehelper wait flag, and remove exec_usermodehelper.
	19	Rusty Russell <rusty@rustcorp.com.au> Jan 2003
	20	*/
1da177e4 LT	21	#include <linux/module.h>
	22	#include <linux/sched.h>
	23	#include <linux/syscalls.h>
	24	#include <linux/unistd.h>
	25	#include <linux/kmod.h>
1da177e4	26	#include <linux/slab.h>
6b3286ed	27	#include <linux/mnt_namespace.h>
1da177e4 LT	28	#include <linux/completion.h>
	29	#include <linux/file.h>
	30	#include <linux/workqueue.h>
	31	#include <linux/security.h>
	32	#include <linux/mount.h>
	33	#include <linux/kernel.h>
	34	#include <linux/init.h>
d025c9db	35	#include <linux/resource.h>
1da177e4 LT	36	#include <asm/uaccess.h>
	37
	38	extern int max_threads;
	39
	40	static struct workqueue_struct *khelper_wq;
	41
	42	#ifdef CONFIG_KMOD
	43
	44	/*
	45	modprobe_path is set via /proc/sys.
	46	*/
	47	char modprobe_path[KMOD_PATH_LEN] = "/sbin/modprobe";
	48
	49	/**
	50	* request_module - try to load a kernel module
	51	* @fmt: printf style format string for the name of the module
	52	* @varargs: arguements as specified in the format string
	53	*
	54	* Load a module using the user mode module loader. The function returns
	55	* zero on success or a negative errno code on failure. Note that a
	56	* successful module load does not mean the module did not then unload
	57	* and exit on an error of its own. Callers must check that the service
	58	* they requested is now available not blindly invoke it.
	59	*
	60	* If module auto-loading support is disabled then this function
	61	* becomes a no-operation.
	62	*/
	63	int request_module(const char *fmt, ...)
	64	{
	65	va_list args;
	66	char module_name[MODULE_NAME_LEN];
	67	unsigned int max_modprobes;
	68	int ret;
	69	char *argv[] = { modprobe_path, "-q", "--", module_name, NULL };
	70	static char *envp[] = { "HOME=/",
	71	"TERM=linux",
	72	"PATH=/sbin:/usr/sbin:/bin:/usr/bin",
	73	NULL };
	74	static atomic_t kmod_concurrent = ATOMIC_INIT(0);
	75	#define MAX_KMOD_CONCURRENT 50 /* Completely arbitrary value - KAO */
	76	static int kmod_loop_msg;
	77
	78	va_start(args, fmt);
	79	ret = vsnprintf(module_name, MODULE_NAME_LEN, fmt, args);
	80	va_end(args);
	81	if (ret >= MODULE_NAME_LEN)
	82	return -ENAMETOOLONG;
	83
	84	/* If modprobe needs a service that is in a module, we get a recursive
	85	* loop. Limit the number of running kmod threads to max_threads/2 or
	86	* MAX_KMOD_CONCURRENT, whichever is the smaller. A cleaner method
	87	* would be to run the parents of this process, counting how many times
	88	* kmod was invoked. That would mean accessing the internals of the
	89	* process tables to get the command line, proc_pid_cmdline is static
	90	* and it is not worth changing the proc code just to handle this case.
	91	* KAO.
	92	*
	93	* "trace the ppid" is simple, but will fail if someone's
	94	* parent exits. I think this is as good as it gets. --RR
	95	*/
	96	max_modprobes = min(max_threads/2, MAX_KMOD_CONCURRENT);
	97	atomic_inc(&kmod_concurrent);
	98	if (atomic_read(&kmod_concurrent) > max_modprobes) {
	99	/* We may be blaming an innocent here, but unlikely */
100	if (kmod_loop_msg++ < 5)
101	printk(KERN_ERR
102	"request_module: runaway loop modprobe %s\n",
103	module_name);
104	atomic_dec(&kmod_concurrent);
105	return -ENOMEM;
106	}
107
108	ret = call_usermodehelper(modprobe_path, argv, envp, 1);
109	atomic_dec(&kmod_concurrent);
110	return ret;
111	}
112	EXPORT_SYMBOL(request_module);
113	#endif /* CONFIG_KMOD */
114
115	struct subprocess_info {
65f27f38	116	struct work_struct work;
1da177e4 LT	117	struct completion *complete;
	118	char *path;
	119	char **argv;
	120	char **envp;
7888e7ff	121	struct key *ring;
1da177e4 LT	122	int wait;
1da177e4 LT	123	int retval;
e239ca54	124	struct file *stdin;
1da177e4 LT	125	};
	126
	127	/*
	128	* This is the task which runs the usermode application
	129	*/
	130	static int ____call_usermodehelper(void *data)
	131	{
	132	struct subprocess_info *sub_info = data;
20e1129a	133	struct key new_session, old_session;
1da177e4 LT	134	int retval;
1da177e4 LT	135
7888e7ff	136	/* Unblock all signals and set the session keyring. */
20e1129a	137	new_session = key_get(sub_info->ring);
1da177e4	138	spin_lock_irq(&current->sighand->siglock);
20e1129a	139	old_session = __install_session_keyring(current, new_session);
1da177e4 LT	140	flush_signal_handlers(current, 1);
	141	sigemptyset(&current->blocked);
	142	recalc_sigpending();
	143	spin_unlock_irq(&current->sighand->siglock);
	144
7888e7ff DH	145	key_put(old_session);
7888e7ff DH	146
e239ca54 AK	147	/* Install input pipe when needed */
	148	if (sub_info->stdin) {
	149	struct files_struct *f = current->files;
	150	struct fdtable *fdt;
	151	/* no races because files should be private here */
	152	sys_close(0);
	153	fd_install(0, sub_info->stdin);
	154	spin_lock(&f->file_lock);
	155	fdt = files_fdtable(f);
	156	FD_SET(0, fdt->open_fds);
	157	FD_CLR(0, fdt->close_on_exec);
	158	spin_unlock(&f->file_lock);
d025c9db AK	159
	160	/* and disallow core files too */
	161	current->signal->rlim[RLIMIT_CORE] = (struct rlimit){0, 0};
e239ca54 AK	162	}
e239ca54 AK	163
1da177e4 LT	164	/* We can run anywhere, unlike our parent keventd(). */
	165	set_cpus_allowed(current, CPU_MASK_ALL);
	166
b73a7e76 JE	167	/*
	168	* Our parent is keventd, which runs with elevated scheduling priority.
	169	* Avoid propagating that into the userspace child.
	170	*/
	171	set_user_nice(current, 0);
	172
1da177e4 LT	173	retval = -EPERM;
1da177e4 LT	174	if (current->fs->root)
67608567 AB	175	retval = kernel_execve(sub_info->path,
67608567 AB	176	sub_info->argv, sub_info->envp);
1da177e4 LT	177
	178	/* Exec failed? */
	179	sub_info->retval = retval;
	180	do_exit(0);
	181	}
	182
	183	/* Keventd can't block, but this (a child) can. */
	184	static int wait_for_helper(void *data)
	185	{
	186	struct subprocess_info *sub_info = data;
	187	pid_t pid;
1da177e4 LT	188
	189	/* Install a handler: if SIGCLD isn't handled sys_wait4 won't
	190	* populate the status, but will return -ECHILD. */
1da177e4 LT	191	allow_signal(SIGCHLD);
	192
	193	pid = kernel_thread(____call_usermodehelper, sub_info, SIGCHLD);
	194	if (pid < 0) {
	195	sub_info->retval = pid;
	196	} else {
111dbe0c BS	197	int ret;
111dbe0c BS	198
1da177e4 LT	199	/*
	200	* Normally it is bogus to call wait4() from in-kernel because
	201	* wait4() wants to write the exit code to a userspace address.
	202	* But wait_for_helper() always runs as keventd, and put_user()
	203	* to a kernel address works OK for kernel threads, due to their
	204	* having an mm_segment_t which spans the entire address space.
	205	*
	206	* Thus the __user pointer cast is valid here.
	207	*/
111dbe0c BS	208	sys_wait4(pid, (int __user *)&ret, 0, NULL);
	209
	210	/*
	211	* If ret is 0, either ____call_usermodehelper failed and the
	212	* real error code is already in sub_info->retval or
	213	* sub_info->retval is 0 anyway, so don't mess with it then.
	214	*/
	215	if (ret)
	216	sub_info->retval = ret;
1da177e4 LT	217	}
1da177e4 LT	218
a98f0dd3 AK	219	if (sub_info->wait < 0)
	220	kfree(sub_info);
	221	else
	222	complete(sub_info->complete);
1da177e4 LT	223	return 0;
	224	}
	225
	226	/* This is run by khelper thread */
65f27f38	227	static void __call_usermodehelper(struct work_struct *work)
1da177e4	228	{
65f27f38 DH	229	struct subprocess_info *sub_info =
65f27f38 DH	230	container_of(work, struct subprocess_info, work);
1da177e4	231	pid_t pid;
e4b69aa2	232	int wait = sub_info->wait;
1da177e4 LT	233
	234	/* CLONE_VFORK: wait until the usermode helper has execve'd
	235	* successfully We need the data structures to stay around
	236	* until that is done. */
e4b69aa2	237	if (wait)
1da177e4 LT	238	pid = kernel_thread(wait_for_helper, sub_info,
	239	CLONE_FS \| CLONE_FILES \| SIGCHLD);
	240	else
	241	pid = kernel_thread(____call_usermodehelper, sub_info,
	242	CLONE_VFORK \| SIGCHLD);
	243
a98f0dd3 AK	244	if (wait < 0)
	245	return;
	246
1da177e4 LT	247	if (pid < 0) {
	248	sub_info->retval = pid;
	249	complete(sub_info->complete);
e4b69aa2	250	} else if (!wait)
1da177e4 LT	251	complete(sub_info->complete);
	252	}
	253
	254	/**
7888e7ff	255	* call_usermodehelper_keys - start a usermode application
1da177e4 LT	256	* @path: pathname for the application
	257	* @argv: null-terminated argument list
	258	* @envp: null-terminated environment list
7888e7ff	259	* @session_keyring: session keyring for process (NULL for an empty keyring)
1da177e4	260	* @wait: wait for the application to finish and return status.
a98f0dd3 AK	261	* when -1 don't wait at all, but you get no useful error back when
	262	* the program couldn't be exec'ed. This makes it safe to call
	263	* from interrupt context.
1da177e4 LT	264	*
	265	* Runs a user-space application. The application is started
	266	* asynchronously if wait is not set, and runs as a child of keventd.
	267	* (ie. it runs with full root capabilities).
	268	*
	269	* Must be called from process context. Returns a negative error code
	270	* if program was not execed successfully, or 0.
	271	*/
7888e7ff DH	272	int call_usermodehelper_keys(char path, char argv, char *envp,
7888e7ff DH	273	struct key *session_keyring, int wait)
1da177e4	274	{
60be6b9a	275	DECLARE_COMPLETION_ONSTACK(done);
a98f0dd3 AK	276	struct subprocess_info *sub_info;
a98f0dd3 AK	277	int retval;
1da177e4 LT	278
	279	if (!khelper_wq)
	280	return -EBUSY;
	281
	282	if (path[0] == '\0')
	283	return 0;
	284
a98f0dd3 AK	285	sub_info = kzalloc(sizeof(struct subprocess_info), GFP_ATOMIC);
	286	if (!sub_info)
	287	return -ENOMEM;
	288
	289	INIT_WORK(&sub_info->work, __call_usermodehelper);
	290	sub_info->complete = &done;
	291	sub_info->path = path;
	292	sub_info->argv = argv;
	293	sub_info->envp = envp;
	294	sub_info->ring = session_keyring;
	295	sub_info->wait = wait;
	296
	297	queue_work(khelper_wq, &sub_info->work);
	298	if (wait < 0) /* task has freed sub_info */
	299	return 0;
1da177e4	300	wait_for_completion(&done);
a98f0dd3 AK	301	retval = sub_info->retval;
	302	kfree(sub_info);
	303	return retval;
1da177e4	304	}
7888e7ff	305	EXPORT_SYMBOL(call_usermodehelper_keys);
1da177e4	306
e239ca54 AK	307	int call_usermodehelper_pipe(char path, char argv, char *envp,
	308	struct file **filp)
	309	{
	310	DECLARE_COMPLETION(done);
	311	struct subprocess_info sub_info = {
65f27f38 DH	312	.work = __WORK_INITIALIZER(sub_info.work,
65f27f38 DH	313	__call_usermodehelper),
e239ca54 AK	314	.complete = &done,
	315	.path = path,
	316	.argv = argv,
	317	.envp = envp,
	318	.retval = 0,
	319	};
	320	struct file *f;
e239ca54 AK	321
	322	if (!khelper_wq)
	323	return -EBUSY;
	324
	325	if (path[0] == '\0')
	326	return 0;
	327
	328	f = create_write_pipe();
3cce4856 AM	329	if (IS_ERR(f))
3cce4856 AM	330	return PTR_ERR(f);
e239ca54 AK	331	*filp = f;
	332
	333	f = create_read_pipe(f);
3cce4856	334	if (IS_ERR(f)) {
e239ca54	335	free_write_pipe(*filp);
3cce4856	336	return PTR_ERR(f);
e239ca54 AK	337	}
	338	sub_info.stdin = f;
	339
65f27f38	340	queue_work(khelper_wq, &sub_info.work);
e239ca54 AK	341	wait_for_completion(&done);
	342	return sub_info.retval;
	343	}
	344	EXPORT_SYMBOL(call_usermodehelper_pipe);
	345
1da177e4 LT	346	void __init usermodehelper_init(void)
	347	{
	348	khelper_wq = create_singlethread_workqueue("khelper");
	349	BUG_ON(!khelper_wq);
	350	}