VisionFive2 Linux kernel

diff --git a/fs/dlm/user.c b/fs/dlm/user.c
new file mode 100644
index 000000000000..1f05960a916f
--- /dev/null
+++ b/fs/dlm/user.c
@@ -0,0 +1,769 @@
+/*
+ * Copyright (C) 2006 Red Hat, Inc.  All rights reserved.
+ *
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU General Public License v.2.
+ */
+
+#include <linux/miscdevice.h>
+#include <linux/init.h>
+#include <linux/wait.h>
+#include <linux/module.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/poll.h>
+#include <linux/signal.h>
+#include <linux/spinlock.h>
+#include <linux/dlm.h>
+#include <linux/dlm_device.h>
+
+#include "dlm_internal.h"
+#include "lockspace.h"
+#include "lock.h"
+#include "lvb_table.h"
+
+static const char *name_prefix="dlm";
+static struct miscdevice ctl_device;
+static struct file_operations device_fops;
+
+#ifdef CONFIG_COMPAT
+
+struct dlm_lock_params32 {
+	__u8 mode;
+	__u8 namelen;
+	__u16 flags;
+	__u32 lkid;
+	__u32 parent;
+
+	__u32 castparam;
+	__u32 castaddr;
+	__u32 bastparam;
+	__u32 bastaddr;
+	__u32 lksb;
+
+	char lvb[DLM_USER_LVB_LEN];
+	char name[0];
+};
+
+struct dlm_write_request32 {
+	__u32 version[3];
+	__u8 cmd;
+	__u8 is64bit;
+	__u8 unused[2];
+
+	union  {
+		struct dlm_lock_params32 lock;
+		struct dlm_lspace_params lspace;
+	} i;
+};
+
+struct dlm_lksb32 {
+	__u32 sb_status;
+	__u32 sb_lkid;
+	__u8 sb_flags;
+	__u32 sb_lvbptr;
+};
+
+struct dlm_lock_result32 {
+	__u32 length;
+	__u32 user_astaddr;
+	__u32 user_astparam;
+	__u32 user_lksb;
+	struct dlm_lksb32 lksb;
+	__u8 bast_mode;
+	__u8 unused[3];
+	/* Offsets may be zero if no data is present */
+	__u32 lvb_offset;
+};
+
+static void compat_input(struct dlm_write_request *kb,
+			 struct dlm_write_request32 *kb32)
+{
+	kb->version[0] = kb32->version[0];
+	kb->version[1] = kb32->version[1];
+	kb->version[2] = kb32->version[2];
+
+	kb->cmd = kb32->cmd;
+	kb->is64bit = kb32->is64bit;
+	if (kb->cmd == DLM_USER_CREATE_LOCKSPACE ||
+	    kb->cmd == DLM_USER_REMOVE_LOCKSPACE) {
+		kb->i.lspace.flags = kb32->i.lspace.flags;
+		kb->i.lspace.minor = kb32->i.lspace.minor;
+		strcpy(kb->i.lspace.name, kb32->i.lspace.name);
+	} else {
+		kb->i.lock.mode = kb32->i.lock.mode;
+		kb->i.lock.namelen = kb32->i.lock.namelen;
+		kb->i.lock.flags = kb32->i.lock.flags;
+		kb->i.lock.lkid = kb32->i.lock.lkid;
+		kb->i.lock.parent = kb32->i.lock.parent;
+		kb->i.lock.castparam = (void *)(long)kb32->i.lock.castparam;
+		kb->i.lock.castaddr = (void *)(long)kb32->i.lock.castaddr;
+		kb->i.lock.bastparam = (void *)(long)kb32->i.lock.bastparam;
+		kb->i.lock.bastaddr = (void *)(long)kb32->i.lock.bastaddr;
+		kb->i.lock.lksb = (void *)(long)kb32->i.lock.lksb;
+		memcpy(kb->i.lock.lvb, kb32->i.lock.lvb, DLM_USER_LVB_LEN);
+		memcpy(kb->i.lock.name, kb32->i.lock.name, kb->i.lock.namelen);
+	}
+}
+
+static void compat_output(struct dlm_lock_result *res,
+			  struct dlm_lock_result32 *res32)
+{
+	res32->length = res->length - (sizeof(struct dlm_lock_result) -
+				       sizeof(struct dlm_lock_result32));
+	res32->user_astaddr = (__u32)(long)res->user_astaddr;
+	res32->user_astparam = (__u32)(long)res->user_astparam;
+	res32->user_lksb = (__u32)(long)res->user_lksb;
+	res32->bast_mode = res->bast_mode;
+
+	res32->lvb_offset = res->lvb_offset;
+	res32->length = res->length;
+
+	res32->lksb.sb_status = res->lksb.sb_status;
+	res32->lksb.sb_flags = res->lksb.sb_flags;
+	res32->lksb.sb_lkid = res->lksb.sb_lkid;
+	res32->lksb.sb_lvbptr = (__u32)(long)res->lksb.sb_lvbptr;
+}
+#endif
+
+
+void dlm_user_add_ast(struct dlm_lkb *lkb, int type)
+{
+	struct dlm_ls *ls;
+	struct dlm_user_args *ua;
+	struct dlm_user_proc *proc;
+
+	/* dlm_clear_proc_locks() sets ORPHAN/DEAD flag on each
+	   lkb before dealing with it.  We need to check this
+	   flag before taking ls_clear_proc_locks mutex because if
+	   it's set, dlm_clear_proc_locks() holds the mutex. */
+
+	if (lkb->lkb_flags & (DLM_IFL_ORPHAN | DLM_IFL_DEAD)) {
+		/* log_print("user_add_ast skip1 %x", lkb->lkb_flags); */
+		return;
+	}
+
+	ls = lkb->lkb_resource->res_ls;
+	mutex_lock(&ls->ls_clear_proc_locks);
+
+	/* If ORPHAN/DEAD flag is set, it means the process is dead so an ast
+	   can't be delivered.  For ORPHAN's, dlm_clear_proc_locks() freed
+	   lkb->ua so we can't try to use it. */
+
+	if (lkb->lkb_flags & (DLM_IFL_ORPHAN | DLM_IFL_DEAD)) {
+		/* log_print("user_add_ast skip2 %x", lkb->lkb_flags); */
+		goto out;
+	}
+
+	DLM_ASSERT(lkb->lkb_astparam, dlm_print_lkb(lkb););
+	ua = (struct dlm_user_args *)lkb->lkb_astparam;
+	proc = ua->proc;
+
+	if (type == AST_BAST && ua->bastaddr == NULL)
+		goto out;
+
+	spin_lock(&proc->asts_spin);
+	if (!(lkb->lkb_ast_type & (AST_COMP | AST_BAST))) {
+		kref_get(&lkb->lkb_ref);
+		list_add_tail(&lkb->lkb_astqueue, &proc->asts);
+		lkb->lkb_ast_type |= type;
+		wake_up_interruptible(&proc->wait);
+	}
+
+	/* We want to copy the lvb to userspace when the completion
+	   ast is read if the status is 0, the lock has an lvb and
+	   lvb_ops says we should.  We could probably have set_lvb_lock()
+	   set update_user_lvb instead and not need old_mode */
+
+	if ((lkb->lkb_ast_type & AST_COMP) &&
+	    (lkb->lkb_lksb->sb_status == 0) &&
+	    lkb->lkb_lksb->sb_lvbptr &&
+	    dlm_lvb_operations[ua->old_mode + 1][lkb->lkb_grmode + 1])
+		ua->update_user_lvb = 1;
+	else
+		ua->update_user_lvb = 0;
+
+	spin_unlock(&proc->asts_spin);
+ out:
+	mutex_unlock(&ls->ls_clear_proc_locks);
+}
+
+static int device_user_lock(struct dlm_user_proc *proc,
+			    struct dlm_lock_params *params)
+{
+	struct dlm_ls *ls;
+	struct dlm_user_args *ua;
+	int error = -ENOMEM;
+
+	ls = dlm_find_lockspace_local(proc->lockspace);
+	if (!ls)
+		return -ENOENT;
+
+	if (!params->castaddr || !params->lksb) {
+		error = -EINVAL;
+		goto out;
+	}
+
+	ua = kzalloc(sizeof(struct dlm_user_args), GFP_KERNEL);
+	if (!ua)
+		goto out;
+	ua->proc = proc;
+	ua->user_lksb = params->lksb;
+	ua->castparam = params->castparam;
+	ua->castaddr = params->castaddr;
+	ua->bastparam = params->bastparam;
+	ua->bastaddr = params->bastaddr;
+
+	if (params->flags & DLM_LKF_CONVERT)
+		error = dlm_user_convert(ls, ua,
+				         params->mode, params->flags,
+				         params->lkid, params->lvb);
+	else {
+		error = dlm_user_request(ls, ua,
+					 params->mode, params->flags,
+					 params->name, params->namelen,
+					 params->parent);
+		if (!error)
+			error = ua->lksb.sb_lkid;
+	}
+ out:
+	dlm_put_lockspace(ls);
+	return error;
+}
+
+static int device_user_unlock(struct dlm_user_proc *proc,
+			      struct dlm_lock_params *params)
+{
+	struct dlm_ls *ls;
+	struct dlm_user_args *ua;
+	int error = -ENOMEM;
+
+	ls = dlm_find_lockspace_local(proc->lockspace);
+	if (!ls)
+		return -ENOENT;
+
+	ua = kzalloc(sizeof(struct dlm_user_args), GFP_KERNEL);
+	if (!ua)
+		goto out;
+	ua->proc = proc;
+	ua->user_lksb = params->lksb;
+	ua->castparam = params->castparam;
+	ua->castaddr = params->castaddr;
+
+	if (params->flags & DLM_LKF_CANCEL)
+		error = dlm_user_cancel(ls, ua, params->flags, params->lkid);
+	else
+		error = dlm_user_unlock(ls, ua, params->flags, params->lkid,
+					params->lvb);
+ out:
+	dlm_put_lockspace(ls);
+	return error;
+}
+
+static int device_create_lockspace(struct dlm_lspace_params *params)
+{
+	dlm_lockspace_t *lockspace;
+	struct dlm_ls *ls;
+	int error, len;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	error = dlm_new_lockspace(params->name, strlen(params->name),
+				  &lockspace, 0, DLM_USER_LVB_LEN);
+	if (error)
+		return error;
+
+	ls = dlm_find_lockspace_local(lockspace);
+	if (!ls)
+		return -ENOENT;
+
+	error = -ENOMEM;
+	len = strlen(params->name) + strlen(name_prefix) + 2;
+	ls->ls_device.name = kzalloc(len, GFP_KERNEL);
+	if (!ls->ls_device.name)
+		goto fail;
+	snprintf((char *)ls->ls_device.name, len, "%s_%s", name_prefix,
+		 params->name);
+	ls->ls_device.fops = &device_fops;
+	ls->ls_device.minor = MISC_DYNAMIC_MINOR;
+
+	error = misc_register(&ls->ls_device);
+	if (error) {
+		kfree(ls->ls_device.name);
+		goto fail;
+	}
+
+	error = ls->ls_device.minor;
+	dlm_put_lockspace(ls);
+	return error;
+
+ fail:
+	dlm_put_lockspace(ls);
+	dlm_release_lockspace(lockspace, 0);
+	return error;
+}
+
+static int device_remove_lockspace(struct dlm_lspace_params *params)
+{
+	dlm_lockspace_t *lockspace;
+	struct dlm_ls *ls;
+	int error;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EPERM;
+
+	ls = dlm_find_lockspace_device(params->minor);
+	if (!ls)
+		return -ENOENT;
+
+	error = misc_deregister(&ls->ls_device);
+	if (error) {
+		dlm_put_lockspace(ls);
+		goto out;
+	}
+	kfree(ls->ls_device.name);
+
+	lockspace = ls->ls_local_handle;
+
+	/* dlm_release_lockspace waits for references to go to zero,
+	   so all processes will need to close their device for the ls
+	   before the release will procede */
+
+	dlm_put_lockspace(ls);
+	error = dlm_release_lockspace(lockspace, 0);
+out:
+	return error;
+}
+
+/* Check the user's version matches ours */
+static int check_version(struct dlm_write_request *req)
+{
+	if (req->version[0] != DLM_DEVICE_VERSION_MAJOR ||
+	    (req->version[0] == DLM_DEVICE_VERSION_MAJOR &&
+	     req->version[1] > DLM_DEVICE_VERSION_MINOR)) {
+
+		printk(KERN_DEBUG "dlm: process %s (%d) version mismatch "
+		       "user (%d.%d.%d) kernel (%d.%d.%d)\n",
+		       current->comm,
+		       current->pid,
+		       req->version[0],
+		       req->version[1],
+		       req->version[2],
+		       DLM_DEVICE_VERSION_MAJOR,
+		       DLM_DEVICE_VERSION_MINOR,
+		       DLM_DEVICE_VERSION_PATCH);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+/*
+ * device_write
+ *
+ *   device_user_lock
+ *     dlm_user_request -> request_lock
+ *     dlm_user_convert -> convert_lock
+ *
+ *   device_user_unlock
+ *     dlm_user_unlock -> unlock_lock
+ *     dlm_user_cancel -> cancel_lock
+ *
+ *   device_create_lockspace
+ *     dlm_new_lockspace
+ *
+ *   device_remove_lockspace
+ *     dlm_release_lockspace
+ */
+
+/* a write to a lockspace device is a lock or unlock request, a write
+   to the control device is to create/remove a lockspace */
+
+static ssize_t device_write(struct file *file, const char __user *buf,
+			    size_t count, loff_t *ppos)
+{
+	struct dlm_user_proc *proc = file->private_data;
+	struct dlm_write_request *kbuf;
+	sigset_t tmpsig, allsigs;
+	int error;
+
+#ifdef CONFIG_COMPAT
+	if (count < sizeof(struct dlm_write_request32))
+#else
+	if (count < sizeof(struct dlm_write_request))
+#endif
+		return -EINVAL;
+
+	kbuf = kmalloc(count, GFP_KERNEL);
+	if (!kbuf)
+		return -ENOMEM;
+
+	if (copy_from_user(kbuf, buf, count)) {
+		error = -EFAULT;
+		goto out_free;
+	}
+
+	if (check_version(kbuf)) {
+		error = -EBADE;
+		goto out_free;
+	}
+
+#ifdef CONFIG_COMPAT
+	if (!kbuf->is64bit) {
+		struct dlm_write_request32 *k32buf;
+		k32buf = (struct dlm_write_request32 *)kbuf;
+		kbuf = kmalloc(count + (sizeof(struct dlm_write_request) -
+			       sizeof(struct dlm_write_request32)), GFP_KERNEL);
+		if (!kbuf)
+			return -ENOMEM;
+
+		if (proc)
+			set_bit(DLM_PROC_FLAGS_COMPAT, &proc->flags);
+		compat_input(kbuf, k32buf);
+		kfree(k32buf);
+	}
+#endif
+
+	/* do we really need this? can a write happen after a close? */
+	if ((kbuf->cmd == DLM_USER_LOCK || kbuf->cmd == DLM_USER_UNLOCK) &&
+	    test_bit(DLM_PROC_FLAGS_CLOSING, &proc->flags))
+		return -EINVAL;
+
+	sigfillset(&allsigs);
+	sigprocmask(SIG_BLOCK, &allsigs, &tmpsig);
+
+	error = -EINVAL;
+
+	switch (kbuf->cmd)
+	{
+	case DLM_USER_LOCK:
+		if (!proc) {
+			log_print("no locking on control device");
+			goto out_sig;
+		}
+		error = device_user_lock(proc, &kbuf->i.lock);
+		break;
+
+	case DLM_USER_UNLOCK:
+		if (!proc) {
+			log_print("no locking on control device");
+			goto out_sig;
+		}
+		error = device_user_unlock(proc, &kbuf->i.lock);
+		break;
+
+	case DLM_USER_CREATE_LOCKSPACE:
+		if (proc) {
+			log_print("create/remove only on control device");
+			goto out_sig;
+		}
+		error = device_create_lockspace(&kbuf->i.lspace);
+		break;
+
+	case DLM_USER_REMOVE_LOCKSPACE:
+		if (proc) {
+			log_print("create/remove only on control device");
+			goto out_sig;
+		}
+		error = device_remove_lockspace(&kbuf->i.lspace);
+		break;
+
+	default:
+		log_print("Unknown command passed to DLM device : %d\n",
+			  kbuf->cmd);
+	}
+
+ out_sig:
+	sigprocmask(SIG_SETMASK, &tmpsig, NULL);
+	recalc_sigpending();
+ out_free:
+	kfree(kbuf);
+	return error;
+}
+
+/* Every process that opens the lockspace device has its own "proc" structure
+   hanging off the open file that's used to keep track of locks owned by the
+   process and asts that need to be delivered to the process. */
+
+static int device_open(struct inode *inode, struct file *file)
+{
+	struct dlm_user_proc *proc;
+	struct dlm_ls *ls;
+
+	ls = dlm_find_lockspace_device(iminor(inode));
+	if (!ls)
+		return -ENOENT;
+
+	proc = kzalloc(sizeof(struct dlm_user_proc), GFP_KERNEL);
+	if (!proc) {
+		dlm_put_lockspace(ls);
+		return -ENOMEM;
+	}
+
+	proc->lockspace = ls->ls_local_handle;
+	INIT_LIST_HEAD(&proc->asts);
+	INIT_LIST_HEAD(&proc->locks);
+	spin_lock_init(&proc->asts_spin);
+	spin_lock_init(&proc->locks_spin);
+	init_waitqueue_head(&proc->wait);
+	file->private_data = proc;
+
+	return 0;
+}
+
+static int device_close(struct inode *inode, struct file *file)
+{
+	struct dlm_user_proc *proc = file->private_data;
+	struct dlm_ls *ls;
+	sigset_t tmpsig, allsigs;
+
+	ls = dlm_find_lockspace_local(proc->lockspace);
+	if (!ls)
+		return -ENOENT;
+
+	sigfillset(&allsigs);
+	sigprocmask(SIG_BLOCK, &allsigs, &tmpsig);
+
+	set_bit(DLM_PROC_FLAGS_CLOSING, &proc->flags);
+
+	dlm_clear_proc_locks(ls, proc);
+
+	/* at this point no more lkb's should exist for this lockspace,
+	   so there's no chance of dlm_user_add_ast() being called and
+	   looking for lkb->ua->proc */
+
+	kfree(proc);
+	file->private_data = NULL;
+
+	dlm_put_lockspace(ls);
+	dlm_put_lockspace(ls);  /* for the find in device_open() */
+
+	/* FIXME: AUTOFREE: if this ls is no longer used do
+	   device_remove_lockspace() */
+
+	sigprocmask(SIG_SETMASK, &tmpsig, NULL);
+	recalc_sigpending();
+
+	return 0;
+}
+
+static int copy_result_to_user(struct dlm_user_args *ua, int compat, int type,
+			       int bmode, char __user *buf, size_t count)
+{
+#ifdef CONFIG_COMPAT
+	struct dlm_lock_result32 result32;
+#endif
+	struct dlm_lock_result result;
+	void *resultptr;
+	int error=0;
+	int len;
+	int struct_len;
+
+	memset(&result, 0, sizeof(struct dlm_lock_result));
+	memcpy(&result.lksb, &ua->lksb, sizeof(struct dlm_lksb));
+	result.user_lksb = ua->user_lksb;
+
+	/* FIXME: dlm1 provides for the user's bastparam/addr to not be updated
+	   in a conversion unless the conversion is successful.  See code
+	   in dlm_user_convert() for updating ua from ua_tmp.  OpenVMS, though,
+	   notes that a new blocking AST address and parameter are set even if
+	   the conversion fails, so maybe we should just do that. */
+
+	if (type == AST_BAST) {
+		result.user_astaddr = ua->bastaddr;
+		result.user_astparam = ua->bastparam;
+		result.bast_mode = bmode;
+	} else {
+		result.user_astaddr = ua->castaddr;
+		result.user_astparam = ua->castparam;
+	}
+
+#ifdef CONFIG_COMPAT
+	if (compat)
+		len = sizeof(struct dlm_lock_result32);
+	else
+#endif
+		len = sizeof(struct dlm_lock_result);
+	struct_len = len;
+
+	/* copy lvb to userspace if there is one, it's been updated, and
+	   the user buffer has space for it */
+
+	if (ua->update_user_lvb && ua->lksb.sb_lvbptr &&
+	    count >= len + DLM_USER_LVB_LEN) {
+		if (copy_to_user(buf+len, ua->lksb.sb_lvbptr,
+				 DLM_USER_LVB_LEN)) {
+			error = -EFAULT;
+			goto out;
+		}
+
+		result.lvb_offset = len;
+		len += DLM_USER_LVB_LEN;
+	}
+
+	result.length = len;
+	resultptr = &result;
+#ifdef CONFIG_COMPAT
+	if (compat) {
+		compat_output(&result, &result32);
+		resultptr = &result32;
+	}
+#endif
+
+	if (copy_to_user(buf, resultptr, struct_len))
+		error = -EFAULT;
+	else
+		error = len;
+ out:
+	return error;
+}
+
+/* a read returns a single ast described in a struct dlm_lock_result */
+
+static ssize_t device_read(struct file *file, char __user *buf, size_t count,
+			   loff_t *ppos)
+{
+	struct dlm_user_proc *proc = file->private_data;
+	struct dlm_lkb *lkb;
+	struct dlm_user_args *ua;
+	DECLARE_WAITQUEUE(wait, current);
+	int error, type=0, bmode=0, removed = 0;
+
+#ifdef CONFIG_COMPAT
+	if (count < sizeof(struct dlm_lock_result32))
+#else
+	if (count < sizeof(struct dlm_lock_result))
+#endif
+		return -EINVAL;
+
+	/* do we really need this? can a read happen after a close? */
+	if (test_bit(DLM_PROC_FLAGS_CLOSING, &proc->flags))
+		return -EINVAL;
+
+	spin_lock(&proc->asts_spin);
+	if (list_empty(&proc->asts)) {
+		if (file->f_flags & O_NONBLOCK) {
+			spin_unlock(&proc->asts_spin);
+			return -EAGAIN;
+		}
+
+		add_wait_queue(&proc->wait, &wait);
+
+	repeat:
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (list_empty(&proc->asts) && !signal_pending(current)) {
+			spin_unlock(&proc->asts_spin);
+			schedule();
+			spin_lock(&proc->asts_spin);
+			goto repeat;
+		}
+		set_current_state(TASK_RUNNING);
+		remove_wait_queue(&proc->wait, &wait);
+
+		if (signal_pending(current)) {
+			spin_unlock(&proc->asts_spin);
+			return -ERESTARTSYS;
+		}
+	}
+
+	if (list_empty(&proc->asts)) {
+		spin_unlock(&proc->asts_spin);
+		return -EAGAIN;
+	}
+
+	/* there may be both completion and blocking asts to return for
+	   the lkb, don't remove lkb from asts list unless no asts remain */
+
+	lkb = list_entry(proc->asts.next, struct dlm_lkb, lkb_astqueue);
+
+	if (lkb->lkb_ast_type & AST_COMP) {
+		lkb->lkb_ast_type &= ~AST_COMP;
+		type = AST_COMP;
+	} else if (lkb->lkb_ast_type & AST_BAST) {
+		lkb->lkb_ast_type &= ~AST_BAST;
+		type = AST_BAST;
+		bmode = lkb->lkb_bastmode;
+	}
+
+	if (!lkb->lkb_ast_type) {
+		list_del(&lkb->lkb_astqueue);
+		removed = 1;
+	}
+	spin_unlock(&proc->asts_spin);
+
+	ua = (struct dlm_user_args *)lkb->lkb_astparam;
+	error = copy_result_to_user(ua,
+			 	test_bit(DLM_PROC_FLAGS_COMPAT, &proc->flags),
+				type, bmode, buf, count);
+
+	/* removes reference for the proc->asts lists added by
+	   dlm_user_add_ast() and may result in the lkb being freed */
+	if (removed)
+		dlm_put_lkb(lkb);
+
+	return error;
+}
+
+static unsigned int device_poll(struct file *file, poll_table *wait)
+{
+	struct dlm_user_proc *proc = file->private_data;
+
+	poll_wait(file, &proc->wait, wait);
+
+	spin_lock(&proc->asts_spin);
+	if (!list_empty(&proc->asts)) {
+		spin_unlock(&proc->asts_spin);
+		return POLLIN | POLLRDNORM;
+	}
+	spin_unlock(&proc->asts_spin);
+	return 0;
+}
+
+static int ctl_device_open(struct inode *inode, struct file *file)
+{
+	file->private_data = NULL;
+	return 0;
+}
+
+static int ctl_device_close(struct inode *inode, struct file *file)
+{
+	return 0;
+}
+
+static struct file_operations device_fops = {
+	.open    = device_open,
+	.release = device_close,
+	.read    = device_read,
+	.write   = device_write,
+	.poll    = device_poll,
+	.owner   = THIS_MODULE,
+};
+
+static struct file_operations ctl_device_fops = {
+	.open    = ctl_device_open,
+	.release = ctl_device_close,
+	.write   = device_write,
+	.owner   = THIS_MODULE,
+};
+
+int dlm_user_init(void)
+{
+	int error;
+
+	ctl_device.name = "dlm-control";
+	ctl_device.fops = &ctl_device_fops;
+	ctl_device.minor = MISC_DYNAMIC_MINOR;
+
+	error = misc_register(&ctl_device);
+	if (error)
+		log_print("misc_register failed for control device");
+
+	return error;
+}
+
+void dlm_user_exit(void)
+{
+	misc_deregister(&ctl_device);
+}
+