2 * Copyright (C) 2006-2008 Red Hat, Inc. All rights reserved.
4 * This copyrighted material is made available to anyone wishing to use,
5 * modify, copy, or redistribute it subject to the terms and conditions
6 * of the GNU General Public License v.2.
9 #include <linux/miscdevice.h>
10 #include <linux/init.h>
11 #include <linux/wait.h>
12 #include <linux/module.h>
13 #include <linux/file.h>
15 #include <linux/poll.h>
16 #include <linux/signal.h>
17 #include <linux/spinlock.h>
18 #include <linux/dlm.h>
19 #include <linux/dlm_device.h>
21 #include "dlm_internal.h"
22 #include "lockspace.h"
24 #include "lvb_table.h"
27 static const char name_prefix[] = "dlm";
28 static const struct file_operations device_fops;
29 static atomic_t dlm_monitor_opened;
30 static int dlm_monitor_unused = 1;
34 struct dlm_lock_params32 {
48 char lvb[DLM_USER_LVB_LEN];
52 struct dlm_write_request32 {
59 struct dlm_lock_params32 lock;
60 struct dlm_lspace_params lspace;
61 struct dlm_purge_params purge;
72 struct dlm_lock_result32 {
78 struct dlm_lksb32 lksb;
81 /* Offsets may be zero if no data is present */
85 static void compat_input(struct dlm_write_request *kb,
86 struct dlm_write_request32 *kb32,
89 kb->version[0] = kb32->version[0];
90 kb->version[1] = kb32->version[1];
91 kb->version[2] = kb32->version[2];
94 kb->is64bit = kb32->is64bit;
95 if (kb->cmd == DLM_USER_CREATE_LOCKSPACE ||
96 kb->cmd == DLM_USER_REMOVE_LOCKSPACE) {
97 kb->i.lspace.flags = kb32->i.lspace.flags;
98 kb->i.lspace.minor = kb32->i.lspace.minor;
99 memcpy(kb->i.lspace.name, kb32->i.lspace.name, count -
100 offsetof(struct dlm_write_request32, i.lspace.name));
101 } else if (kb->cmd == DLM_USER_PURGE) {
102 kb->i.purge.nodeid = kb32->i.purge.nodeid;
103 kb->i.purge.pid = kb32->i.purge.pid;
105 kb->i.lock.mode = kb32->i.lock.mode;
106 kb->i.lock.namelen = kb32->i.lock.namelen;
107 kb->i.lock.flags = kb32->i.lock.flags;
108 kb->i.lock.lkid = kb32->i.lock.lkid;
109 kb->i.lock.parent = kb32->i.lock.parent;
110 kb->i.lock.xid = kb32->i.lock.xid;
111 kb->i.lock.timeout = kb32->i.lock.timeout;
112 kb->i.lock.castparam = (void *)(long)kb32->i.lock.castparam;
113 kb->i.lock.castaddr = (void *)(long)kb32->i.lock.castaddr;
114 kb->i.lock.bastparam = (void *)(long)kb32->i.lock.bastparam;
115 kb->i.lock.bastaddr = (void *)(long)kb32->i.lock.bastaddr;
116 kb->i.lock.lksb = (void *)(long)kb32->i.lock.lksb;
117 memcpy(kb->i.lock.lvb, kb32->i.lock.lvb, DLM_USER_LVB_LEN);
118 memcpy(kb->i.lock.name, kb32->i.lock.name, count -
119 offsetof(struct dlm_write_request32, i.lock.name));
123 static void compat_output(struct dlm_lock_result *res,
124 struct dlm_lock_result32 *res32)
126 res32->version[0] = res->version[0];
127 res32->version[1] = res->version[1];
128 res32->version[2] = res->version[2];
130 res32->user_astaddr = (__u32)(long)res->user_astaddr;
131 res32->user_astparam = (__u32)(long)res->user_astparam;
132 res32->user_lksb = (__u32)(long)res->user_lksb;
133 res32->bast_mode = res->bast_mode;
135 res32->lvb_offset = res->lvb_offset;
136 res32->length = res->length;
138 res32->lksb.sb_status = res->lksb.sb_status;
139 res32->lksb.sb_flags = res->lksb.sb_flags;
140 res32->lksb.sb_lkid = res->lksb.sb_lkid;
141 res32->lksb.sb_lvbptr = (__u32)(long)res->lksb.sb_lvbptr;
145 /* Figure out if this lock is at the end of its life and no longer
146 available for the application to use. The lkb still exists until
147 the final ast is read. A lock becomes EOL in three situations:
148 1. a noqueue request fails with EAGAIN
149 2. an unlock completes with EUNLOCK
150 3. a cancel of a waiting request completes with ECANCEL/EDEADLK
151 An EOL lock needs to be removed from the process's list of locks.
152 And we can't allow any new operation on an EOL lock. This is
153 not related to the lifetime of the lkb struct which is managed
154 entirely by refcount. */
156 static int lkb_is_endoflife(struct dlm_lkb *lkb, int sb_status, int type)
164 if (lkb->lkb_grmode == DLM_LOCK_IV)
168 if (type == AST_COMP && lkb->lkb_grmode == DLM_LOCK_IV)
175 /* we could possibly check if the cancel of an orphan has resulted in the lkb
176 being removed and then remove that lkb from the orphans list and free it */
178 void dlm_user_add_ast(struct dlm_lkb *lkb, int type)
181 struct dlm_user_args *ua;
182 struct dlm_user_proc *proc;
183 int eol = 0, ast_type;
185 if (lkb->lkb_flags & (DLM_IFL_ORPHAN | DLM_IFL_DEAD))
188 ls = lkb->lkb_resource->res_ls;
189 mutex_lock(&ls->ls_clear_proc_locks);
191 /* If ORPHAN/DEAD flag is set, it means the process is dead so an ast
192 can't be delivered. For ORPHAN's, dlm_clear_proc_locks() freed
193 lkb->ua so we can't try to use it. This second check is necessary
194 for cases where a completion ast is received for an operation that
195 began before clear_proc_locks did its cancel/unlock. */
197 if (lkb->lkb_flags & (DLM_IFL_ORPHAN | DLM_IFL_DEAD))
200 DLM_ASSERT(lkb->lkb_ua, dlm_print_lkb(lkb););
204 if (type == AST_BAST && ua->bastaddr == NULL)
207 spin_lock(&proc->asts_spin);
209 ast_type = lkb->lkb_ast_type;
210 lkb->lkb_ast_type |= type;
213 kref_get(&lkb->lkb_ref);
214 list_add_tail(&lkb->lkb_astqueue, &proc->asts);
215 wake_up_interruptible(&proc->wait);
217 if (type == AST_COMP && (ast_type & AST_COMP))
218 log_debug(ls, "ast overlap %x status %x %x",
219 lkb->lkb_id, ua->lksb.sb_status, lkb->lkb_flags);
221 eol = lkb_is_endoflife(lkb, ua->lksb.sb_status, type);
223 lkb->lkb_ast_type &= ~AST_BAST;
224 lkb->lkb_flags |= DLM_IFL_ENDOFLIFE;
227 /* We want to copy the lvb to userspace when the completion
228 ast is read if the status is 0, the lock has an lvb and
229 lvb_ops says we should. We could probably have set_lvb_lock()
230 set update_user_lvb instead and not need old_mode */
232 if ((lkb->lkb_ast_type & AST_COMP) &&
233 (lkb->lkb_lksb->sb_status == 0) &&
234 lkb->lkb_lksb->sb_lvbptr &&
235 dlm_lvb_operations[ua->old_mode + 1][lkb->lkb_grmode + 1])
236 ua->update_user_lvb = 1;
238 ua->update_user_lvb = 0;
240 spin_unlock(&proc->asts_spin);
243 spin_lock(&proc->locks_spin);
244 if (!list_empty(&lkb->lkb_ownqueue)) {
245 list_del_init(&lkb->lkb_ownqueue);
248 spin_unlock(&proc->locks_spin);
251 mutex_unlock(&ls->ls_clear_proc_locks);
254 static int device_user_lock(struct dlm_user_proc *proc,
255 struct dlm_lock_params *params)
258 struct dlm_user_args *ua;
261 ls = dlm_find_lockspace_local(proc->lockspace);
265 if (!params->castaddr || !params->lksb) {
270 ua = kzalloc(sizeof(struct dlm_user_args), GFP_KERNEL);
274 ua->user_lksb = params->lksb;
275 ua->castparam = params->castparam;
276 ua->castaddr = params->castaddr;
277 ua->bastparam = params->bastparam;
278 ua->bastaddr = params->bastaddr;
279 ua->xid = params->xid;
281 if (params->flags & DLM_LKF_CONVERT)
282 error = dlm_user_convert(ls, ua,
283 params->mode, params->flags,
284 params->lkid, params->lvb,
285 (unsigned long) params->timeout);
287 error = dlm_user_request(ls, ua,
288 params->mode, params->flags,
289 params->name, params->namelen,
290 (unsigned long) params->timeout);
292 error = ua->lksb.sb_lkid;
295 dlm_put_lockspace(ls);
299 static int device_user_unlock(struct dlm_user_proc *proc,
300 struct dlm_lock_params *params)
303 struct dlm_user_args *ua;
306 ls = dlm_find_lockspace_local(proc->lockspace);
310 ua = kzalloc(sizeof(struct dlm_user_args), GFP_KERNEL);
314 ua->user_lksb = params->lksb;
315 ua->castparam = params->castparam;
316 ua->castaddr = params->castaddr;
318 if (params->flags & DLM_LKF_CANCEL)
319 error = dlm_user_cancel(ls, ua, params->flags, params->lkid);
321 error = dlm_user_unlock(ls, ua, params->flags, params->lkid,
324 dlm_put_lockspace(ls);
328 static int device_user_deadlock(struct dlm_user_proc *proc,
329 struct dlm_lock_params *params)
334 ls = dlm_find_lockspace_local(proc->lockspace);
338 error = dlm_user_deadlock(ls, params->flags, params->lkid);
340 dlm_put_lockspace(ls);
344 static int dlm_device_register(struct dlm_ls *ls, char *name)
348 /* The device is already registered. This happens when the
349 lockspace is created multiple times from userspace. */
350 if (ls->ls_device.name)
354 len = strlen(name) + strlen(name_prefix) + 2;
355 ls->ls_device.name = kzalloc(len, GFP_KERNEL);
356 if (!ls->ls_device.name)
359 snprintf((char *)ls->ls_device.name, len, "%s_%s", name_prefix,
361 ls->ls_device.fops = &device_fops;
362 ls->ls_device.minor = MISC_DYNAMIC_MINOR;
364 error = misc_register(&ls->ls_device);
366 kfree(ls->ls_device.name);
372 int dlm_device_deregister(struct dlm_ls *ls)
376 /* The device is not registered. This happens when the lockspace
377 was never used from userspace, or when device_create_lockspace()
378 calls dlm_release_lockspace() after the register fails. */
379 if (!ls->ls_device.name)
382 error = misc_deregister(&ls->ls_device);
384 kfree(ls->ls_device.name);
388 static int device_user_purge(struct dlm_user_proc *proc,
389 struct dlm_purge_params *params)
394 ls = dlm_find_lockspace_local(proc->lockspace);
398 error = dlm_user_purge(ls, proc, params->nodeid, params->pid);
400 dlm_put_lockspace(ls);
404 static int device_create_lockspace(struct dlm_lspace_params *params)
406 dlm_lockspace_t *lockspace;
410 if (!capable(CAP_SYS_ADMIN))
413 error = dlm_new_lockspace(params->name, strlen(params->name),
414 &lockspace, params->flags, DLM_USER_LVB_LEN);
418 ls = dlm_find_lockspace_local(lockspace);
422 error = dlm_device_register(ls, params->name);
423 dlm_put_lockspace(ls);
426 dlm_release_lockspace(lockspace, 0);
428 error = ls->ls_device.minor;
433 static int device_remove_lockspace(struct dlm_lspace_params *params)
435 dlm_lockspace_t *lockspace;
437 int error, force = 0;
439 if (!capable(CAP_SYS_ADMIN))
442 ls = dlm_find_lockspace_device(params->minor);
446 if (params->flags & DLM_USER_LSFLG_FORCEFREE)
449 lockspace = ls->ls_local_handle;
450 dlm_put_lockspace(ls);
452 /* The final dlm_release_lockspace waits for references to go to
453 zero, so all processes will need to close their device for the
454 ls before the release will proceed. release also calls the
455 device_deregister above. Converting a positive return value
456 from release to zero means that userspace won't know when its
457 release was the final one, but it shouldn't need to know. */
459 error = dlm_release_lockspace(lockspace, force);
465 /* Check the user's version matches ours */
466 static int check_version(struct dlm_write_request *req)
468 if (req->version[0] != DLM_DEVICE_VERSION_MAJOR ||
469 (req->version[0] == DLM_DEVICE_VERSION_MAJOR &&
470 req->version[1] > DLM_DEVICE_VERSION_MINOR)) {
472 printk(KERN_DEBUG "dlm: process %s (%d) version mismatch "
473 "user (%d.%d.%d) kernel (%d.%d.%d)\n",
475 task_pid_nr(current),
479 DLM_DEVICE_VERSION_MAJOR,
480 DLM_DEVICE_VERSION_MINOR,
481 DLM_DEVICE_VERSION_PATCH);
491 * dlm_user_request -> request_lock
492 * dlm_user_convert -> convert_lock
495 * dlm_user_unlock -> unlock_lock
496 * dlm_user_cancel -> cancel_lock
498 * device_create_lockspace
501 * device_remove_lockspace
502 * dlm_release_lockspace
505 /* a write to a lockspace device is a lock or unlock request, a write
506 to the control device is to create/remove a lockspace */
508 static ssize_t device_write(struct file *file, const char __user *buf,
509 size_t count, loff_t *ppos)
511 struct dlm_user_proc *proc = file->private_data;
512 struct dlm_write_request *kbuf;
513 sigset_t tmpsig, allsigs;
517 if (count < sizeof(struct dlm_write_request32))
519 if (count < sizeof(struct dlm_write_request))
523 kbuf = kzalloc(count + 1, GFP_KERNEL);
527 if (copy_from_user(kbuf, buf, count)) {
532 if (check_version(kbuf)) {
538 if (!kbuf->is64bit) {
539 struct dlm_write_request32 *k32buf;
540 k32buf = (struct dlm_write_request32 *)kbuf;
541 kbuf = kmalloc(count + 1 + (sizeof(struct dlm_write_request) -
542 sizeof(struct dlm_write_request32)), GFP_KERNEL);
549 set_bit(DLM_PROC_FLAGS_COMPAT, &proc->flags);
550 compat_input(kbuf, k32buf, count + 1);
555 /* do we really need this? can a write happen after a close? */
556 if ((kbuf->cmd == DLM_USER_LOCK || kbuf->cmd == DLM_USER_UNLOCK) &&
557 (proc && test_bit(DLM_PROC_FLAGS_CLOSING, &proc->flags))) {
562 sigfillset(&allsigs);
563 sigprocmask(SIG_BLOCK, &allsigs, &tmpsig);
571 log_print("no locking on control device");
574 error = device_user_lock(proc, &kbuf->i.lock);
577 case DLM_USER_UNLOCK:
579 log_print("no locking on control device");
582 error = device_user_unlock(proc, &kbuf->i.lock);
585 case DLM_USER_DEADLOCK:
587 log_print("no locking on control device");
590 error = device_user_deadlock(proc, &kbuf->i.lock);
593 case DLM_USER_CREATE_LOCKSPACE:
595 log_print("create/remove only on control device");
598 error = device_create_lockspace(&kbuf->i.lspace);
601 case DLM_USER_REMOVE_LOCKSPACE:
603 log_print("create/remove only on control device");
606 error = device_remove_lockspace(&kbuf->i.lspace);
611 log_print("no locking on control device");
614 error = device_user_purge(proc, &kbuf->i.purge);
618 log_print("Unknown command passed to DLM device : %d\n",
623 sigprocmask(SIG_SETMASK, &tmpsig, NULL);
630 /* Every process that opens the lockspace device has its own "proc" structure
631 hanging off the open file that's used to keep track of locks owned by the
632 process and asts that need to be delivered to the process. */
634 static int device_open(struct inode *inode, struct file *file)
636 struct dlm_user_proc *proc;
639 ls = dlm_find_lockspace_device(iminor(inode));
643 proc = kzalloc(sizeof(struct dlm_user_proc), GFP_KERNEL);
645 dlm_put_lockspace(ls);
649 proc->lockspace = ls->ls_local_handle;
650 INIT_LIST_HEAD(&proc->asts);
651 INIT_LIST_HEAD(&proc->locks);
652 INIT_LIST_HEAD(&proc->unlocking);
653 spin_lock_init(&proc->asts_spin);
654 spin_lock_init(&proc->locks_spin);
655 init_waitqueue_head(&proc->wait);
656 file->private_data = proc;
661 static int device_close(struct inode *inode, struct file *file)
663 struct dlm_user_proc *proc = file->private_data;
665 sigset_t tmpsig, allsigs;
667 ls = dlm_find_lockspace_local(proc->lockspace);
671 sigfillset(&allsigs);
672 sigprocmask(SIG_BLOCK, &allsigs, &tmpsig);
674 set_bit(DLM_PROC_FLAGS_CLOSING, &proc->flags);
676 dlm_clear_proc_locks(ls, proc);
678 /* at this point no more lkb's should exist for this lockspace,
679 so there's no chance of dlm_user_add_ast() being called and
680 looking for lkb->ua->proc */
683 file->private_data = NULL;
685 dlm_put_lockspace(ls);
686 dlm_put_lockspace(ls); /* for the find in device_open() */
688 /* FIXME: AUTOFREE: if this ls is no longer used do
689 device_remove_lockspace() */
691 sigprocmask(SIG_SETMASK, &tmpsig, NULL);
697 static int copy_result_to_user(struct dlm_user_args *ua, int compat, int type,
698 int bmode, char __user *buf, size_t count)
701 struct dlm_lock_result32 result32;
703 struct dlm_lock_result result;
709 memset(&result, 0, sizeof(struct dlm_lock_result));
710 result.version[0] = DLM_DEVICE_VERSION_MAJOR;
711 result.version[1] = DLM_DEVICE_VERSION_MINOR;
712 result.version[2] = DLM_DEVICE_VERSION_PATCH;
713 memcpy(&result.lksb, &ua->lksb, sizeof(struct dlm_lksb));
714 result.user_lksb = ua->user_lksb;
716 /* FIXME: dlm1 provides for the user's bastparam/addr to not be updated
717 in a conversion unless the conversion is successful. See code
718 in dlm_user_convert() for updating ua from ua_tmp. OpenVMS, though,
719 notes that a new blocking AST address and parameter are set even if
720 the conversion fails, so maybe we should just do that. */
722 if (type == AST_BAST) {
723 result.user_astaddr = ua->bastaddr;
724 result.user_astparam = ua->bastparam;
725 result.bast_mode = bmode;
727 result.user_astaddr = ua->castaddr;
728 result.user_astparam = ua->castparam;
733 len = sizeof(struct dlm_lock_result32);
736 len = sizeof(struct dlm_lock_result);
739 /* copy lvb to userspace if there is one, it's been updated, and
740 the user buffer has space for it */
742 if (ua->update_user_lvb && ua->lksb.sb_lvbptr &&
743 count >= len + DLM_USER_LVB_LEN) {
744 if (copy_to_user(buf+len, ua->lksb.sb_lvbptr,
750 result.lvb_offset = len;
751 len += DLM_USER_LVB_LEN;
758 compat_output(&result, &result32);
759 resultptr = &result32;
763 if (copy_to_user(buf, resultptr, struct_len))
771 static int copy_version_to_user(char __user *buf, size_t count)
773 struct dlm_device_version ver;
775 memset(&ver, 0, sizeof(struct dlm_device_version));
776 ver.version[0] = DLM_DEVICE_VERSION_MAJOR;
777 ver.version[1] = DLM_DEVICE_VERSION_MINOR;
778 ver.version[2] = DLM_DEVICE_VERSION_PATCH;
780 if (copy_to_user(buf, &ver, sizeof(struct dlm_device_version)))
782 return sizeof(struct dlm_device_version);
785 /* a read returns a single ast described in a struct dlm_lock_result */
787 static ssize_t device_read(struct file *file, char __user *buf, size_t count,
790 struct dlm_user_proc *proc = file->private_data;
792 DECLARE_WAITQUEUE(wait, current);
793 int error, type=0, bmode=0, removed = 0;
795 if (count == sizeof(struct dlm_device_version)) {
796 error = copy_version_to_user(buf, count);
801 log_print("non-version read from control device %zu", count);
806 if (count < sizeof(struct dlm_lock_result32))
808 if (count < sizeof(struct dlm_lock_result))
812 /* do we really need this? can a read happen after a close? */
813 if (test_bit(DLM_PROC_FLAGS_CLOSING, &proc->flags))
816 spin_lock(&proc->asts_spin);
817 if (list_empty(&proc->asts)) {
818 if (file->f_flags & O_NONBLOCK) {
819 spin_unlock(&proc->asts_spin);
823 add_wait_queue(&proc->wait, &wait);
826 set_current_state(TASK_INTERRUPTIBLE);
827 if (list_empty(&proc->asts) && !signal_pending(current)) {
828 spin_unlock(&proc->asts_spin);
830 spin_lock(&proc->asts_spin);
833 set_current_state(TASK_RUNNING);
834 remove_wait_queue(&proc->wait, &wait);
836 if (signal_pending(current)) {
837 spin_unlock(&proc->asts_spin);
842 /* there may be both completion and blocking asts to return for
843 the lkb, don't remove lkb from asts list unless no asts remain */
845 lkb = list_entry(proc->asts.next, struct dlm_lkb, lkb_astqueue);
847 if (lkb->lkb_ast_type & AST_COMP) {
848 lkb->lkb_ast_type &= ~AST_COMP;
850 } else if (lkb->lkb_ast_type & AST_BAST) {
851 lkb->lkb_ast_type &= ~AST_BAST;
853 bmode = lkb->lkb_bastmode;
856 if (!lkb->lkb_ast_type) {
857 list_del(&lkb->lkb_astqueue);
860 spin_unlock(&proc->asts_spin);
862 error = copy_result_to_user(lkb->lkb_ua,
863 test_bit(DLM_PROC_FLAGS_COMPAT, &proc->flags),
864 type, bmode, buf, count);
866 /* removes reference for the proc->asts lists added by
867 dlm_user_add_ast() and may result in the lkb being freed */
874 static unsigned int device_poll(struct file *file, poll_table *wait)
876 struct dlm_user_proc *proc = file->private_data;
878 poll_wait(file, &proc->wait, wait);
880 spin_lock(&proc->asts_spin);
881 if (!list_empty(&proc->asts)) {
882 spin_unlock(&proc->asts_spin);
883 return POLLIN | POLLRDNORM;
885 spin_unlock(&proc->asts_spin);
889 int dlm_user_daemon_available(void)
891 /* dlm_controld hasn't started (or, has started, but not
892 properly populated configfs) */
894 if (!dlm_our_nodeid())
897 /* This is to deal with versions of dlm_controld that don't
898 know about the monitor device. We assume that if the
899 dlm_controld was started (above), but the monitor device
900 was never opened, that it's an old version. dlm_controld
901 should open the monitor device before populating configfs. */
903 if (dlm_monitor_unused)
906 return atomic_read(&dlm_monitor_opened) ? 1 : 0;
909 static int ctl_device_open(struct inode *inode, struct file *file)
911 file->private_data = NULL;
915 static int ctl_device_close(struct inode *inode, struct file *file)
920 static int monitor_device_open(struct inode *inode, struct file *file)
922 atomic_inc(&dlm_monitor_opened);
923 dlm_monitor_unused = 0;
927 static int monitor_device_close(struct inode *inode, struct file *file)
929 if (atomic_dec_and_test(&dlm_monitor_opened))
930 dlm_stop_lockspaces();
934 static const struct file_operations device_fops = {
936 .release = device_close,
938 .write = device_write,
940 .owner = THIS_MODULE,
943 static const struct file_operations ctl_device_fops = {
944 .open = ctl_device_open,
945 .release = ctl_device_close,
947 .write = device_write,
948 .owner = THIS_MODULE,
951 static struct miscdevice ctl_device = {
952 .name = "dlm-control",
953 .fops = &ctl_device_fops,
954 .minor = MISC_DYNAMIC_MINOR,
957 static const struct file_operations monitor_device_fops = {
958 .open = monitor_device_open,
959 .release = monitor_device_close,
960 .owner = THIS_MODULE,
963 static struct miscdevice monitor_device = {
964 .name = "dlm-monitor",
965 .fops = &monitor_device_fops,
966 .minor = MISC_DYNAMIC_MINOR,
969 int __init dlm_user_init(void)
973 atomic_set(&dlm_monitor_opened, 0);
975 error = misc_register(&ctl_device);
977 log_print("misc_register failed for control device");
981 error = misc_register(&monitor_device);
983 log_print("misc_register failed for monitor device");
984 misc_deregister(&ctl_device);
990 void dlm_user_exit(void)
992 misc_deregister(&ctl_device);
993 misc_deregister(&monitor_device);