2 * Copyright (C) 2006-2010 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>
20 #include <linux/slab.h>
22 #include "dlm_internal.h"
23 #include "lockspace.h"
25 #include "lvb_table.h"
29 static const char name_prefix[] = "dlm";
30 static const struct file_operations device_fops;
31 static atomic_t dlm_monitor_opened;
32 static int dlm_monitor_unused = 1;
36 struct dlm_lock_params32 {
50 char lvb[DLM_USER_LVB_LEN];
54 struct dlm_write_request32 {
61 struct dlm_lock_params32 lock;
62 struct dlm_lspace_params lspace;
63 struct dlm_purge_params purge;
74 struct dlm_lock_result32 {
80 struct dlm_lksb32 lksb;
83 /* Offsets may be zero if no data is present */
87 static void compat_input(struct dlm_write_request *kb,
88 struct dlm_write_request32 *kb32,
91 kb->version[0] = kb32->version[0];
92 kb->version[1] = kb32->version[1];
93 kb->version[2] = kb32->version[2];
96 kb->is64bit = kb32->is64bit;
97 if (kb->cmd == DLM_USER_CREATE_LOCKSPACE ||
98 kb->cmd == DLM_USER_REMOVE_LOCKSPACE) {
99 kb->i.lspace.flags = kb32->i.lspace.flags;
100 kb->i.lspace.minor = kb32->i.lspace.minor;
101 memcpy(kb->i.lspace.name, kb32->i.lspace.name, namelen);
102 } else if (kb->cmd == DLM_USER_PURGE) {
103 kb->i.purge.nodeid = kb32->i.purge.nodeid;
104 kb->i.purge.pid = kb32->i.purge.pid;
106 kb->i.lock.mode = kb32->i.lock.mode;
107 kb->i.lock.namelen = kb32->i.lock.namelen;
108 kb->i.lock.flags = kb32->i.lock.flags;
109 kb->i.lock.lkid = kb32->i.lock.lkid;
110 kb->i.lock.parent = kb32->i.lock.parent;
111 kb->i.lock.xid = kb32->i.lock.xid;
112 kb->i.lock.timeout = kb32->i.lock.timeout;
113 kb->i.lock.castparam = (void *)(long)kb32->i.lock.castparam;
114 kb->i.lock.castaddr = (void *)(long)kb32->i.lock.castaddr;
115 kb->i.lock.bastparam = (void *)(long)kb32->i.lock.bastparam;
116 kb->i.lock.bastaddr = (void *)(long)kb32->i.lock.bastaddr;
117 kb->i.lock.lksb = (void *)(long)kb32->i.lock.lksb;
118 memcpy(kb->i.lock.lvb, kb32->i.lock.lvb, DLM_USER_LVB_LEN);
119 memcpy(kb->i.lock.name, kb32->i.lock.name, namelen);
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(int mode, int status)
165 if (mode == DLM_LOCK_IV)
172 /* we could possibly check if the cancel of an orphan has resulted in the lkb
173 being removed and then remove that lkb from the orphans list and free it */
175 void dlm_user_add_ast(struct dlm_lkb *lkb, uint32_t flags, int mode,
176 int status, uint32_t sbflags, uint64_t seq)
179 struct dlm_user_args *ua;
180 struct dlm_user_proc *proc;
183 if (lkb->lkb_flags & (DLM_IFL_ORPHAN | DLM_IFL_DEAD))
186 ls = lkb->lkb_resource->res_ls;
187 mutex_lock(&ls->ls_clear_proc_locks);
189 /* If ORPHAN/DEAD flag is set, it means the process is dead so an ast
190 can't be delivered. For ORPHAN's, dlm_clear_proc_locks() freed
191 lkb->ua so we can't try to use it. This second check is necessary
192 for cases where a completion ast is received for an operation that
193 began before clear_proc_locks did its cancel/unlock. */
195 if (lkb->lkb_flags & (DLM_IFL_ORPHAN | DLM_IFL_DEAD))
198 DLM_ASSERT(lkb->lkb_ua, dlm_print_lkb(lkb););
202 if ((flags & DLM_CB_BAST) && ua->bastaddr == NULL)
205 if ((flags & DLM_CB_CAST) && lkb_is_endoflife(mode, status))
206 lkb->lkb_flags |= DLM_IFL_ENDOFLIFE;
208 spin_lock(&proc->asts_spin);
210 rv = dlm_add_lkb_callback(lkb, flags, mode, status, sbflags, seq);
212 spin_unlock(&proc->asts_spin);
216 if (list_empty(&lkb->lkb_cb_list)) {
217 kref_get(&lkb->lkb_ref);
218 list_add_tail(&lkb->lkb_cb_list, &proc->asts);
219 wake_up_interruptible(&proc->wait);
221 spin_unlock(&proc->asts_spin);
223 if (lkb->lkb_flags & DLM_IFL_ENDOFLIFE) {
224 /* N.B. spin_lock locks_spin, not asts_spin */
225 spin_lock(&proc->locks_spin);
226 if (!list_empty(&lkb->lkb_ownqueue)) {
227 list_del_init(&lkb->lkb_ownqueue);
230 spin_unlock(&proc->locks_spin);
233 mutex_unlock(&ls->ls_clear_proc_locks);
236 static int device_user_lock(struct dlm_user_proc *proc,
237 struct dlm_lock_params *params)
240 struct dlm_user_args *ua;
243 ls = dlm_find_lockspace_local(proc->lockspace);
247 if (!params->castaddr || !params->lksb) {
252 ua = kzalloc(sizeof(struct dlm_user_args), GFP_NOFS);
256 ua->user_lksb = params->lksb;
257 ua->castparam = params->castparam;
258 ua->castaddr = params->castaddr;
259 ua->bastparam = params->bastparam;
260 ua->bastaddr = params->bastaddr;
261 ua->xid = params->xid;
263 if (params->flags & DLM_LKF_CONVERT)
264 error = dlm_user_convert(ls, ua,
265 params->mode, params->flags,
266 params->lkid, params->lvb,
267 (unsigned long) params->timeout);
269 error = dlm_user_request(ls, ua,
270 params->mode, params->flags,
271 params->name, params->namelen,
272 (unsigned long) params->timeout);
274 error = ua->lksb.sb_lkid;
277 dlm_put_lockspace(ls);
281 static int device_user_unlock(struct dlm_user_proc *proc,
282 struct dlm_lock_params *params)
285 struct dlm_user_args *ua;
288 ls = dlm_find_lockspace_local(proc->lockspace);
292 ua = kzalloc(sizeof(struct dlm_user_args), GFP_NOFS);
296 ua->user_lksb = params->lksb;
297 ua->castparam = params->castparam;
298 ua->castaddr = params->castaddr;
300 if (params->flags & DLM_LKF_CANCEL)
301 error = dlm_user_cancel(ls, ua, params->flags, params->lkid);
303 error = dlm_user_unlock(ls, ua, params->flags, params->lkid,
306 dlm_put_lockspace(ls);
310 static int device_user_deadlock(struct dlm_user_proc *proc,
311 struct dlm_lock_params *params)
316 ls = dlm_find_lockspace_local(proc->lockspace);
320 error = dlm_user_deadlock(ls, params->flags, params->lkid);
322 dlm_put_lockspace(ls);
326 static int dlm_device_register(struct dlm_ls *ls, char *name)
330 /* The device is already registered. This happens when the
331 lockspace is created multiple times from userspace. */
332 if (ls->ls_device.name)
336 len = strlen(name) + strlen(name_prefix) + 2;
337 ls->ls_device.name = kzalloc(len, GFP_NOFS);
338 if (!ls->ls_device.name)
341 snprintf((char *)ls->ls_device.name, len, "%s_%s", name_prefix,
343 ls->ls_device.fops = &device_fops;
344 ls->ls_device.minor = MISC_DYNAMIC_MINOR;
346 error = misc_register(&ls->ls_device);
348 kfree(ls->ls_device.name);
349 /* this has to be set to NULL
350 * to avoid a double-free in dlm_device_deregister
352 ls->ls_device.name = NULL;
358 int dlm_device_deregister(struct dlm_ls *ls)
362 /* The device is not registered. This happens when the lockspace
363 was never used from userspace, or when device_create_lockspace()
364 calls dlm_release_lockspace() after the register fails. */
365 if (!ls->ls_device.name)
368 error = misc_deregister(&ls->ls_device);
370 kfree(ls->ls_device.name);
374 static int device_user_purge(struct dlm_user_proc *proc,
375 struct dlm_purge_params *params)
380 ls = dlm_find_lockspace_local(proc->lockspace);
384 error = dlm_user_purge(ls, proc, params->nodeid, params->pid);
386 dlm_put_lockspace(ls);
390 static int device_create_lockspace(struct dlm_lspace_params *params)
392 dlm_lockspace_t *lockspace;
396 if (!capable(CAP_SYS_ADMIN))
399 error = dlm_new_lockspace(params->name, strlen(params->name),
400 &lockspace, params->flags, DLM_USER_LVB_LEN);
404 ls = dlm_find_lockspace_local(lockspace);
408 error = dlm_device_register(ls, params->name);
409 dlm_put_lockspace(ls);
412 dlm_release_lockspace(lockspace, 0);
414 error = ls->ls_device.minor;
419 static int device_remove_lockspace(struct dlm_lspace_params *params)
421 dlm_lockspace_t *lockspace;
423 int error, force = 0;
425 if (!capable(CAP_SYS_ADMIN))
428 ls = dlm_find_lockspace_device(params->minor);
432 if (params->flags & DLM_USER_LSFLG_FORCEFREE)
435 lockspace = ls->ls_local_handle;
436 dlm_put_lockspace(ls);
438 /* The final dlm_release_lockspace waits for references to go to
439 zero, so all processes will need to close their device for the
440 ls before the release will proceed. release also calls the
441 device_deregister above. Converting a positive return value
442 from release to zero means that userspace won't know when its
443 release was the final one, but it shouldn't need to know. */
445 error = dlm_release_lockspace(lockspace, force);
451 /* Check the user's version matches ours */
452 static int check_version(struct dlm_write_request *req)
454 if (req->version[0] != DLM_DEVICE_VERSION_MAJOR ||
455 (req->version[0] == DLM_DEVICE_VERSION_MAJOR &&
456 req->version[1] > DLM_DEVICE_VERSION_MINOR)) {
458 printk(KERN_DEBUG "dlm: process %s (%d) version mismatch "
459 "user (%d.%d.%d) kernel (%d.%d.%d)\n",
461 task_pid_nr(current),
465 DLM_DEVICE_VERSION_MAJOR,
466 DLM_DEVICE_VERSION_MINOR,
467 DLM_DEVICE_VERSION_PATCH);
477 * dlm_user_request -> request_lock
478 * dlm_user_convert -> convert_lock
481 * dlm_user_unlock -> unlock_lock
482 * dlm_user_cancel -> cancel_lock
484 * device_create_lockspace
487 * device_remove_lockspace
488 * dlm_release_lockspace
491 /* a write to a lockspace device is a lock or unlock request, a write
492 to the control device is to create/remove a lockspace */
494 static ssize_t device_write(struct file *file, const char __user *buf,
495 size_t count, loff_t *ppos)
497 struct dlm_user_proc *proc = file->private_data;
498 struct dlm_write_request *kbuf;
499 sigset_t tmpsig, allsigs;
503 if (count < sizeof(struct dlm_write_request32))
505 if (count < sizeof(struct dlm_write_request))
509 kbuf = kzalloc(count + 1, GFP_NOFS);
513 if (copy_from_user(kbuf, buf, count)) {
518 if (check_version(kbuf)) {
524 if (!kbuf->is64bit) {
525 struct dlm_write_request32 *k32buf;
528 if (count > sizeof(struct dlm_write_request32))
529 namelen = count - sizeof(struct dlm_write_request32);
531 k32buf = (struct dlm_write_request32 *)kbuf;
533 /* add 1 after namelen so that the name string is terminated */
534 kbuf = kzalloc(sizeof(struct dlm_write_request) + namelen + 1,
542 set_bit(DLM_PROC_FLAGS_COMPAT, &proc->flags);
544 compat_input(kbuf, k32buf, namelen);
549 /* do we really need this? can a write happen after a close? */
550 if ((kbuf->cmd == DLM_USER_LOCK || kbuf->cmd == DLM_USER_UNLOCK) &&
551 (proc && test_bit(DLM_PROC_FLAGS_CLOSING, &proc->flags))) {
556 sigfillset(&allsigs);
557 sigprocmask(SIG_BLOCK, &allsigs, &tmpsig);
565 log_print("no locking on control device");
568 error = device_user_lock(proc, &kbuf->i.lock);
571 case DLM_USER_UNLOCK:
573 log_print("no locking on control device");
576 error = device_user_unlock(proc, &kbuf->i.lock);
579 case DLM_USER_DEADLOCK:
581 log_print("no locking on control device");
584 error = device_user_deadlock(proc, &kbuf->i.lock);
587 case DLM_USER_CREATE_LOCKSPACE:
589 log_print("create/remove only on control device");
592 error = device_create_lockspace(&kbuf->i.lspace);
595 case DLM_USER_REMOVE_LOCKSPACE:
597 log_print("create/remove only on control device");
600 error = device_remove_lockspace(&kbuf->i.lspace);
605 log_print("no locking on control device");
608 error = device_user_purge(proc, &kbuf->i.purge);
612 log_print("Unknown command passed to DLM device : %d\n",
617 sigprocmask(SIG_SETMASK, &tmpsig, NULL);
623 /* Every process that opens the lockspace device has its own "proc" structure
624 hanging off the open file that's used to keep track of locks owned by the
625 process and asts that need to be delivered to the process. */
627 static int device_open(struct inode *inode, struct file *file)
629 struct dlm_user_proc *proc;
632 ls = dlm_find_lockspace_device(iminor(inode));
636 proc = kzalloc(sizeof(struct dlm_user_proc), GFP_NOFS);
638 dlm_put_lockspace(ls);
642 proc->lockspace = ls->ls_local_handle;
643 INIT_LIST_HEAD(&proc->asts);
644 INIT_LIST_HEAD(&proc->locks);
645 INIT_LIST_HEAD(&proc->unlocking);
646 spin_lock_init(&proc->asts_spin);
647 spin_lock_init(&proc->locks_spin);
648 init_waitqueue_head(&proc->wait);
649 file->private_data = proc;
654 static int device_close(struct inode *inode, struct file *file)
656 struct dlm_user_proc *proc = file->private_data;
658 sigset_t tmpsig, allsigs;
660 ls = dlm_find_lockspace_local(proc->lockspace);
664 sigfillset(&allsigs);
665 sigprocmask(SIG_BLOCK, &allsigs, &tmpsig);
667 set_bit(DLM_PROC_FLAGS_CLOSING, &proc->flags);
669 dlm_clear_proc_locks(ls, proc);
671 /* at this point no more lkb's should exist for this lockspace,
672 so there's no chance of dlm_user_add_ast() being called and
673 looking for lkb->ua->proc */
676 file->private_data = NULL;
678 dlm_put_lockspace(ls);
679 dlm_put_lockspace(ls); /* for the find in device_open() */
681 /* FIXME: AUTOFREE: if this ls is no longer used do
682 device_remove_lockspace() */
684 sigprocmask(SIG_SETMASK, &tmpsig, NULL);
690 static int copy_result_to_user(struct dlm_user_args *ua, int compat,
691 uint32_t flags, int mode, int copy_lvb,
692 char __user *buf, size_t count)
695 struct dlm_lock_result32 result32;
697 struct dlm_lock_result result;
703 memset(&result, 0, sizeof(struct dlm_lock_result));
704 result.version[0] = DLM_DEVICE_VERSION_MAJOR;
705 result.version[1] = DLM_DEVICE_VERSION_MINOR;
706 result.version[2] = DLM_DEVICE_VERSION_PATCH;
707 memcpy(&result.lksb, &ua->lksb, sizeof(struct dlm_lksb));
708 result.user_lksb = ua->user_lksb;
710 /* FIXME: dlm1 provides for the user's bastparam/addr to not be updated
711 in a conversion unless the conversion is successful. See code
712 in dlm_user_convert() for updating ua from ua_tmp. OpenVMS, though,
713 notes that a new blocking AST address and parameter are set even if
714 the conversion fails, so maybe we should just do that. */
716 if (flags & DLM_CB_BAST) {
717 result.user_astaddr = ua->bastaddr;
718 result.user_astparam = ua->bastparam;
719 result.bast_mode = mode;
721 result.user_astaddr = ua->castaddr;
722 result.user_astparam = ua->castparam;
727 len = sizeof(struct dlm_lock_result32);
730 len = sizeof(struct dlm_lock_result);
733 /* copy lvb to userspace if there is one, it's been updated, and
734 the user buffer has space for it */
736 if (copy_lvb && ua->lksb.sb_lvbptr && count >= len + DLM_USER_LVB_LEN) {
737 if (copy_to_user(buf+len, ua->lksb.sb_lvbptr,
743 result.lvb_offset = len;
744 len += DLM_USER_LVB_LEN;
751 compat_output(&result, &result32);
752 resultptr = &result32;
756 if (copy_to_user(buf, resultptr, struct_len))
764 static int copy_version_to_user(char __user *buf, size_t count)
766 struct dlm_device_version ver;
768 memset(&ver, 0, sizeof(struct dlm_device_version));
769 ver.version[0] = DLM_DEVICE_VERSION_MAJOR;
770 ver.version[1] = DLM_DEVICE_VERSION_MINOR;
771 ver.version[2] = DLM_DEVICE_VERSION_PATCH;
773 if (copy_to_user(buf, &ver, sizeof(struct dlm_device_version)))
775 return sizeof(struct dlm_device_version);
778 /* a read returns a single ast described in a struct dlm_lock_result */
780 static ssize_t device_read(struct file *file, char __user *buf, size_t count,
783 struct dlm_user_proc *proc = file->private_data;
785 DECLARE_WAITQUEUE(wait, current);
786 struct dlm_callback cb;
787 int rv, resid, copy_lvb = 0;
789 if (count == sizeof(struct dlm_device_version)) {
790 rv = copy_version_to_user(buf, count);
795 log_print("non-version read from control device %zu", count);
800 if (count < sizeof(struct dlm_lock_result32))
802 if (count < sizeof(struct dlm_lock_result))
808 /* do we really need this? can a read happen after a close? */
809 if (test_bit(DLM_PROC_FLAGS_CLOSING, &proc->flags))
812 spin_lock(&proc->asts_spin);
813 if (list_empty(&proc->asts)) {
814 if (file->f_flags & O_NONBLOCK) {
815 spin_unlock(&proc->asts_spin);
819 add_wait_queue(&proc->wait, &wait);
822 set_current_state(TASK_INTERRUPTIBLE);
823 if (list_empty(&proc->asts) && !signal_pending(current)) {
824 spin_unlock(&proc->asts_spin);
826 spin_lock(&proc->asts_spin);
829 set_current_state(TASK_RUNNING);
830 remove_wait_queue(&proc->wait, &wait);
832 if (signal_pending(current)) {
833 spin_unlock(&proc->asts_spin);
838 /* if we empty lkb_callbacks, we don't want to unlock the spinlock
839 without removing lkb_cb_list; so empty lkb_cb_list is always
840 consistent with empty lkb_callbacks */
842 lkb = list_entry(proc->asts.next, struct dlm_lkb, lkb_cb_list);
844 rv = dlm_rem_lkb_callback(lkb->lkb_resource->res_ls, lkb, &cb, &resid);
846 /* this shouldn't happen; lkb should have been removed from
847 list when resid was zero */
848 log_print("dlm_rem_lkb_callback empty %x", lkb->lkb_id);
849 list_del_init(&lkb->lkb_cb_list);
850 spin_unlock(&proc->asts_spin);
851 /* removes ref for proc->asts, may cause lkb to be freed */
856 list_del_init(&lkb->lkb_cb_list);
857 spin_unlock(&proc->asts_spin);
859 if (cb.flags & DLM_CB_SKIP) {
860 /* removes ref for proc->asts, may cause lkb to be freed */
866 if (cb.flags & DLM_CB_CAST) {
867 int old_mode, new_mode;
869 old_mode = lkb->lkb_last_cast.mode;
872 if (!cb.sb_status && lkb->lkb_lksb->sb_lvbptr &&
873 dlm_lvb_operations[old_mode + 1][new_mode + 1])
876 lkb->lkb_lksb->sb_status = cb.sb_status;
877 lkb->lkb_lksb->sb_flags = cb.sb_flags;
880 rv = copy_result_to_user(lkb->lkb_ua,
881 test_bit(DLM_PROC_FLAGS_COMPAT, &proc->flags),
882 cb.flags, cb.mode, copy_lvb, buf, count);
884 /* removes ref for proc->asts, may cause lkb to be freed */
891 static unsigned int device_poll(struct file *file, poll_table *wait)
893 struct dlm_user_proc *proc = file->private_data;
895 poll_wait(file, &proc->wait, wait);
897 spin_lock(&proc->asts_spin);
898 if (!list_empty(&proc->asts)) {
899 spin_unlock(&proc->asts_spin);
900 return POLLIN | POLLRDNORM;
902 spin_unlock(&proc->asts_spin);
906 int dlm_user_daemon_available(void)
908 /* dlm_controld hasn't started (or, has started, but not
909 properly populated configfs) */
911 if (!dlm_our_nodeid())
914 /* This is to deal with versions of dlm_controld that don't
915 know about the monitor device. We assume that if the
916 dlm_controld was started (above), but the monitor device
917 was never opened, that it's an old version. dlm_controld
918 should open the monitor device before populating configfs. */
920 if (dlm_monitor_unused)
923 return atomic_read(&dlm_monitor_opened) ? 1 : 0;
926 static int ctl_device_open(struct inode *inode, struct file *file)
928 file->private_data = NULL;
932 static int ctl_device_close(struct inode *inode, struct file *file)
937 static int monitor_device_open(struct inode *inode, struct file *file)
939 atomic_inc(&dlm_monitor_opened);
940 dlm_monitor_unused = 0;
944 static int monitor_device_close(struct inode *inode, struct file *file)
946 if (atomic_dec_and_test(&dlm_monitor_opened))
947 dlm_stop_lockspaces();
951 static const struct file_operations device_fops = {
953 .release = device_close,
955 .write = device_write,
957 .owner = THIS_MODULE,
958 .llseek = noop_llseek,
961 static const struct file_operations ctl_device_fops = {
962 .open = ctl_device_open,
963 .release = ctl_device_close,
965 .write = device_write,
966 .owner = THIS_MODULE,
967 .llseek = noop_llseek,
970 static struct miscdevice ctl_device = {
971 .name = "dlm-control",
972 .fops = &ctl_device_fops,
973 .minor = MISC_DYNAMIC_MINOR,
976 static const struct file_operations monitor_device_fops = {
977 .open = monitor_device_open,
978 .release = monitor_device_close,
979 .owner = THIS_MODULE,
980 .llseek = noop_llseek,
983 static struct miscdevice monitor_device = {
984 .name = "dlm-monitor",
985 .fops = &monitor_device_fops,
986 .minor = MISC_DYNAMIC_MINOR,
989 int __init dlm_user_init(void)
993 atomic_set(&dlm_monitor_opened, 0);
995 error = misc_register(&ctl_device);
997 log_print("misc_register failed for control device");
1001 error = misc_register(&monitor_device);
1003 log_print("misc_register failed for monitor device");
1004 misc_deregister(&ctl_device);
1010 void dlm_user_exit(void)
1012 misc_deregister(&ctl_device);
1013 misc_deregister(&monitor_device);